2 * sgen-gc.c: Simple generational GC.
5 * Paolo Molaro (lupus@ximian.com)
6 * Rodrigo Kumpera (kumpera@gmail.com)
8 * Copyright 2005-2011 Novell, Inc (http://www.novell.com)
9 * Copyright 2011 Xamarin Inc (http://www.xamarin.com)
11 * Thread start/stop adapted from Boehm's GC:
12 * Copyright (c) 1994 by Xerox Corporation. All rights reserved.
13 * Copyright (c) 1996 by Silicon Graphics. All rights reserved.
14 * Copyright (c) 1998 by Fergus Henderson. All rights reserved.
15 * Copyright (c) 2000-2004 by Hewlett-Packard Company. All rights reserved.
16 * Copyright 2001-2003 Ximian, Inc
17 * Copyright 2003-2010 Novell, Inc.
18 * Copyright 2011 Xamarin, Inc.
19 * Copyright (C) 2012 Xamarin Inc
21 * This library is free software; you can redistribute it and/or
22 * modify it under the terms of the GNU Library General Public
23 * License 2.0 as published by the Free Software Foundation;
25 * This library is distributed in the hope that it will be useful,
26 * but WITHOUT ANY WARRANTY; without even the implied warranty of
27 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
28 * Library General Public License for more details.
30 * You should have received a copy of the GNU Library General Public
31 * License 2.0 along with this library; if not, write to the Free
32 * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
34 * Important: allocation provides always zeroed memory, having to do
35 * a memset after allocation is deadly for performance.
36 * Memory usage at startup is currently as follows:
38 * 64 KB internal space
40 * We should provide a small memory config with half the sizes
42 * We currently try to make as few mono assumptions as possible:
43 * 1) 2-word header with no GC pointers in it (first vtable, second to store the
45 * 2) gc descriptor is the second word in the vtable (first word in the class)
46 * 3) 8 byte alignment is the minimum and enough (not true for special structures (SIMD), FIXME)
47 * 4) there is a function to get an object's size and the number of
48 * elements in an array.
49 * 5) we know the special way bounds are allocated for complex arrays
50 * 6) we know about proxies and how to treat them when domains are unloaded
52 * Always try to keep stack usage to a minimum: no recursive behaviour
53 * and no large stack allocs.
55 * General description.
56 * Objects are initially allocated in a nursery using a fast bump-pointer technique.
57 * When the nursery is full we start a nursery collection: this is performed with a
59 * When the old generation is full we start a copying GC of the old generation as well:
60 * this will be changed to mark&sweep with copying when fragmentation becomes to severe
61 * in the future. Maybe we'll even do both during the same collection like IMMIX.
63 * The things that complicate this description are:
64 * *) pinned objects: we can't move them so we need to keep track of them
65 * *) no precise info of the thread stacks and registers: we need to be able to
66 * quickly find the objects that may be referenced conservatively and pin them
67 * (this makes the first issues more important)
68 * *) large objects are too expensive to be dealt with using copying GC: we handle them
69 * with mark/sweep during major collections
70 * *) some objects need to not move even if they are small (interned strings, Type handles):
71 * we use mark/sweep for them, too: they are not allocated in the nursery, but inside
72 * PinnedChunks regions
78 *) we could have a function pointer in MonoClass to implement
79 customized write barriers for value types
81 *) investigate the stuff needed to advance a thread to a GC-safe
82 point (single-stepping, read from unmapped memory etc) and implement it.
83 This would enable us to inline allocations and write barriers, for example,
84 or at least parts of them, like the write barrier checks.
85 We may need this also for handling precise info on stacks, even simple things
86 as having uninitialized data on the stack and having to wait for the prolog
87 to zero it. Not an issue for the last frame that we scan conservatively.
88 We could always not trust the value in the slots anyway.
90 *) modify the jit to save info about references in stack locations:
91 this can be done just for locals as a start, so that at least
92 part of the stack is handled precisely.
94 *) test/fix endianess issues
96 *) Implement a card table as the write barrier instead of remembered
97 sets? Card tables are not easy to implement with our current
98 memory layout. We have several different kinds of major heap
99 objects: Small objects in regular blocks, small objects in pinned
100 chunks and LOS objects. If we just have a pointer we have no way
101 to tell which kind of object it points into, therefore we cannot
102 know where its card table is. The least we have to do to make
103 this happen is to get rid of write barriers for indirect stores.
106 *) Get rid of write barriers for indirect stores. We can do this by
107 telling the GC to wbarrier-register an object once we do an ldloca
108 or ldelema on it, and to unregister it once it's not used anymore
109 (it can only travel downwards on the stack). The problem with
110 unregistering is that it needs to happen eventually no matter
111 what, even if exceptions are thrown, the thread aborts, etc.
112 Rodrigo suggested that we could do only the registering part and
113 let the collector find out (pessimistically) when it's safe to
114 unregister, namely when the stack pointer of the thread that
115 registered the object is higher than it was when the registering
116 happened. This might make for a good first implementation to get
117 some data on performance.
119 *) Some sort of blacklist support? Blacklists is a concept from the
120 Boehm GC: if during a conservative scan we find pointers to an
121 area which we might use as heap, we mark that area as unusable, so
122 pointer retention by random pinning pointers is reduced.
124 *) experiment with max small object size (very small right now - 2kb,
125 because it's tied to the max freelist size)
127 *) add an option to mmap the whole heap in one chunk: it makes for many
128 simplifications in the checks (put the nursery at the top and just use a single
129 check for inclusion/exclusion): the issue this has is that on 32 bit systems it's
130 not flexible (too much of the address space may be used by default or we can't
131 increase the heap as needed) and we'd need a race-free mechanism to return memory
132 back to the system (mprotect(PROT_NONE) will still keep the memory allocated if it
133 was written to, munmap is needed, but the following mmap may not find the same segment
136 *) memzero the major fragments after restarting the world and optionally a smaller
139 *) investigate having fragment zeroing threads
141 *) separate locks for finalization and other minor stuff to reduce
144 *) try a different copying order to improve memory locality
146 *) a thread abort after a store but before the write barrier will
147 prevent the write barrier from executing
149 *) specialized dynamically generated markers/copiers
151 *) Dynamically adjust TLAB size to the number of threads. If we have
152 too many threads that do allocation, we might need smaller TLABs,
153 and we might get better performance with larger TLABs if we only
154 have a handful of threads. We could sum up the space left in all
155 assigned TLABs and if that's more than some percentage of the
156 nursery size, reduce the TLAB size.
158 *) Explore placing unreachable objects on unused nursery memory.
159 Instead of memset'ng a region to zero, place an int[] covering it.
160 A good place to start is add_nursery_frag. The tricky thing here is
161 placing those objects atomically outside of a collection.
163 *) Allocation should use asymmetric Dekker synchronization:
164 http://blogs.oracle.com/dave/resource/Asymmetric-Dekker-Synchronization.txt
165 This should help weak consistency archs.
172 #define _XOPEN_SOURCE
173 #define _DARWIN_C_SOURCE
179 #ifdef HAVE_PTHREAD_H
182 #ifdef HAVE_PTHREAD_NP_H
183 #include <pthread_np.h>
191 #include "mono/sgen/sgen-gc.h"
192 #include "mono/sgen/sgen-cardtable.h"
193 #include "mono/sgen/sgen-protocol.h"
194 #include "mono/sgen/sgen-memory-governor.h"
195 #include "mono/sgen/sgen-hash-table.h"
196 #include "mono/sgen/sgen-cardtable.h"
197 #include "mono/sgen/sgen-pinning.h"
198 #include "mono/sgen/sgen-workers.h"
199 #include "mono/sgen/sgen-client.h"
200 #include "mono/sgen/sgen-pointer-queue.h"
201 #include "mono/sgen/gc-internal-agnostic.h"
202 #include "mono/utils/mono-proclib.h"
203 #include "mono/utils/mono-memory-model.h"
204 #include "mono/utils/hazard-pointer.h"
206 #include <mono/utils/memcheck.h>
208 #undef pthread_create
210 #undef pthread_detach
213 * ######################################################################
214 * ######## Types and constants used by the GC.
215 * ######################################################################
218 /* 0 means not initialized, 1 is initialized, -1 means in progress */
219 static int gc_initialized = 0;
220 /* If set, check if we need to do something every X allocations */
221 gboolean has_per_allocation_action;
222 /* If set, do a heap check every X allocation */
223 guint32 verify_before_allocs = 0;
224 /* If set, do a minor collection before every X allocation */
225 guint32 collect_before_allocs = 0;
226 /* If set, do a whole heap check before each collection */
227 static gboolean whole_heap_check_before_collection = FALSE;
228 /* If set, do a heap consistency check before each minor collection */
229 static gboolean consistency_check_at_minor_collection = FALSE;
230 /* If set, do a mod union consistency check before each finishing collection pause */
231 static gboolean mod_union_consistency_check = FALSE;
232 /* If set, check whether mark bits are consistent after major collections */
233 static gboolean check_mark_bits_after_major_collection = FALSE;
234 /* If set, check that all nursery objects are pinned/not pinned, depending on context */
235 static gboolean check_nursery_objects_pinned = FALSE;
236 /* If set, do a few checks when the concurrent collector is used */
237 static gboolean do_concurrent_checks = FALSE;
238 /* If set, do a plausibility check on the scan_starts before and after
240 static gboolean do_scan_starts_check = FALSE;
242 static gboolean disable_minor_collections = FALSE;
243 static gboolean disable_major_collections = FALSE;
244 static gboolean do_verify_nursery = FALSE;
245 static gboolean do_dump_nursery_content = FALSE;
246 static gboolean enable_nursery_canaries = FALSE;
248 #ifdef HEAVY_STATISTICS
249 guint64 stat_objects_alloced_degraded = 0;
250 guint64 stat_bytes_alloced_degraded = 0;
252 guint64 stat_copy_object_called_nursery = 0;
253 guint64 stat_objects_copied_nursery = 0;
254 guint64 stat_copy_object_called_major = 0;
255 guint64 stat_objects_copied_major = 0;
257 guint64 stat_scan_object_called_nursery = 0;
258 guint64 stat_scan_object_called_major = 0;
260 guint64 stat_slots_allocated_in_vain;
262 guint64 stat_nursery_copy_object_failed_from_space = 0;
263 guint64 stat_nursery_copy_object_failed_forwarded = 0;
264 guint64 stat_nursery_copy_object_failed_pinned = 0;
265 guint64 stat_nursery_copy_object_failed_to_space = 0;
267 static guint64 stat_wbarrier_add_to_global_remset = 0;
268 static guint64 stat_wbarrier_arrayref_copy = 0;
269 static guint64 stat_wbarrier_generic_store = 0;
270 static guint64 stat_wbarrier_generic_store_atomic = 0;
271 static guint64 stat_wbarrier_set_root = 0;
274 static guint64 stat_pinned_objects = 0;
276 static guint64 time_minor_pre_collection_fragment_clear = 0;
277 static guint64 time_minor_pinning = 0;
278 static guint64 time_minor_scan_remsets = 0;
279 static guint64 time_minor_scan_pinned = 0;
280 static guint64 time_minor_scan_roots = 0;
281 static guint64 time_minor_finish_gray_stack = 0;
282 static guint64 time_minor_fragment_creation = 0;
284 static guint64 time_major_pre_collection_fragment_clear = 0;
285 static guint64 time_major_pinning = 0;
286 static guint64 time_major_scan_pinned = 0;
287 static guint64 time_major_scan_roots = 0;
288 static guint64 time_major_scan_mod_union = 0;
289 static guint64 time_major_finish_gray_stack = 0;
290 static guint64 time_major_free_bigobjs = 0;
291 static guint64 time_major_los_sweep = 0;
292 static guint64 time_major_sweep = 0;
293 static guint64 time_major_fragment_creation = 0;
295 static guint64 time_max = 0;
297 static SGEN_TV_DECLARE (time_major_conc_collection_start);
298 static SGEN_TV_DECLARE (time_major_conc_collection_end);
300 static SGEN_TV_DECLARE (last_minor_collection_start_tv);
301 static SGEN_TV_DECLARE (last_minor_collection_end_tv);
303 int gc_debug_level = 0;
308 mono_gc_flush_info (void)
310 fflush (gc_debug_file);
314 #define TV_DECLARE SGEN_TV_DECLARE
315 #define TV_GETTIME SGEN_TV_GETTIME
316 #define TV_ELAPSED SGEN_TV_ELAPSED
318 static SGEN_TV_DECLARE (sgen_init_timestamp);
320 NurseryClearPolicy nursery_clear_policy = CLEAR_AT_TLAB_CREATION;
322 #define object_is_forwarded SGEN_OBJECT_IS_FORWARDED
323 #define object_is_pinned SGEN_OBJECT_IS_PINNED
324 #define pin_object SGEN_PIN_OBJECT
326 #define ptr_in_nursery sgen_ptr_in_nursery
328 #define LOAD_VTABLE SGEN_LOAD_VTABLE
331 nursery_canaries_enabled (void)
333 return enable_nursery_canaries;
336 #define safe_object_get_size sgen_safe_object_get_size
339 * ######################################################################
340 * ######## Global data.
341 * ######################################################################
343 MonoCoopMutex gc_mutex;
344 gboolean sgen_try_free_some_memory;
346 #define SCAN_START_SIZE SGEN_SCAN_START_SIZE
348 size_t degraded_mode = 0;
350 static mword bytes_pinned_from_failed_allocation = 0;
352 GCMemSection *nursery_section = NULL;
353 static volatile mword lowest_heap_address = ~(mword)0;
354 static volatile mword highest_heap_address = 0;
356 MonoCoopMutex sgen_interruption_mutex;
358 int current_collection_generation = -1;
359 static volatile gboolean concurrent_collection_in_progress = FALSE;
361 /* objects that are ready to be finalized */
362 static SgenPointerQueue fin_ready_queue = SGEN_POINTER_QUEUE_INIT (INTERNAL_MEM_FINALIZE_READY);
363 static SgenPointerQueue critical_fin_queue = SGEN_POINTER_QUEUE_INIT (INTERNAL_MEM_FINALIZE_READY);
365 /* registered roots: the key to the hash is the root start address */
367 * Different kinds of roots are kept separate to speed up pin_from_roots () for example.
369 SgenHashTable roots_hash [ROOT_TYPE_NUM] = {
370 SGEN_HASH_TABLE_INIT (INTERNAL_MEM_ROOTS_TABLE, INTERNAL_MEM_ROOT_RECORD, sizeof (RootRecord), sgen_aligned_addr_hash, NULL),
371 SGEN_HASH_TABLE_INIT (INTERNAL_MEM_ROOTS_TABLE, INTERNAL_MEM_ROOT_RECORD, sizeof (RootRecord), sgen_aligned_addr_hash, NULL),
372 SGEN_HASH_TABLE_INIT (INTERNAL_MEM_ROOTS_TABLE, INTERNAL_MEM_ROOT_RECORD, sizeof (RootRecord), sgen_aligned_addr_hash, NULL)
374 static mword roots_size = 0; /* amount of memory in the root set */
376 /* The size of a TLAB */
377 /* The bigger the value, the less often we have to go to the slow path to allocate a new
378 * one, but the more space is wasted by threads not allocating much memory.
380 * FIXME: Make this self-tuning for each thread.
382 guint32 tlab_size = (1024 * 4);
384 #define MAX_SMALL_OBJ_SIZE SGEN_MAX_SMALL_OBJ_SIZE
386 #define ALLOC_ALIGN SGEN_ALLOC_ALIGN
388 #define ALIGN_UP SGEN_ALIGN_UP
390 #ifdef SGEN_DEBUG_INTERNAL_ALLOC
391 MonoNativeThreadId main_gc_thread = NULL;
394 /*Object was pinned during the current collection*/
395 static mword objects_pinned;
398 * ######################################################################
399 * ######## Macros and function declarations.
400 * ######################################################################
403 typedef SgenGrayQueue GrayQueue;
405 /* forward declarations */
406 static void scan_from_registered_roots (char *addr_start, char *addr_end, int root_type, ScanCopyContext ctx);
408 static void pin_from_roots (void *start_nursery, void *end_nursery, ScanCopyContext ctx);
409 static void finish_gray_stack (int generation, ScanCopyContext ctx);
412 SgenMajorCollector major_collector;
413 SgenMinorCollector sgen_minor_collector;
414 /* FIXME: get rid of this */
415 static GrayQueue gray_queue;
417 static SgenRememberedSet remset;
419 /* The gray queue to use from the main collection thread. */
420 #define WORKERS_DISTRIBUTE_GRAY_QUEUE (&gray_queue)
423 * The gray queue a worker job must use. If we're not parallel or
424 * concurrent, we use the main gray queue.
426 static SgenGrayQueue*
427 sgen_workers_get_job_gray_queue (WorkerData *worker_data)
429 return worker_data ? &worker_data->private_gray_queue : WORKERS_DISTRIBUTE_GRAY_QUEUE;
433 gray_queue_redirect (SgenGrayQueue *queue)
435 gboolean wake = FALSE;
438 GrayQueueSection *section = sgen_gray_object_dequeue_section (queue);
441 sgen_section_gray_queue_enqueue ((SgenSectionGrayQueue *)queue->alloc_prepare_data, section);
446 g_assert (concurrent_collection_in_progress);
447 sgen_workers_ensure_awake ();
452 gray_queue_enable_redirect (SgenGrayQueue *queue)
454 if (!concurrent_collection_in_progress)
457 sgen_gray_queue_set_alloc_prepare (queue, gray_queue_redirect, sgen_workers_get_distribute_section_gray_queue ());
458 gray_queue_redirect (queue);
462 sgen_scan_area_with_callback (char *start, char *end, IterateObjectCallbackFunc callback, void *data, gboolean allow_flags, gboolean fail_on_canaries)
464 while (start < end) {
468 if (!*(void**)start) {
469 start += sizeof (void*); /* should be ALLOC_ALIGN, really */
474 if (!(obj = (char *)SGEN_OBJECT_IS_FORWARDED (start)))
480 if (!sgen_client_object_is_array_fill ((GCObject*)obj)) {
481 CHECK_CANARY_FOR_OBJECT ((GCObject*)obj, fail_on_canaries);
482 size = ALIGN_UP (safe_object_get_size ((GCObject*)obj));
483 callback ((GCObject*)obj, size, data);
484 CANARIFY_SIZE (size);
486 size = ALIGN_UP (safe_object_get_size ((GCObject*)obj));
494 * sgen_add_to_global_remset:
496 * The global remset contains locations which point into newspace after
497 * a minor collection. This can happen if the objects they point to are pinned.
499 * LOCKING: If called from a parallel collector, the global remset
500 * lock must be held. For serial collectors that is not necessary.
503 sgen_add_to_global_remset (gpointer ptr, GCObject *obj)
505 SGEN_ASSERT (5, sgen_ptr_in_nursery (obj), "Target pointer of global remset must be in the nursery");
507 HEAVY_STAT (++stat_wbarrier_add_to_global_remset);
509 if (!major_collector.is_concurrent) {
510 SGEN_ASSERT (5, current_collection_generation != -1, "Global remsets can only be added during collections");
512 if (current_collection_generation == -1)
513 SGEN_ASSERT (5, sgen_concurrent_collection_in_progress (), "Global remsets outside of collection pauses can only be added by the concurrent collector");
516 if (!object_is_pinned (obj))
517 SGEN_ASSERT (5, sgen_minor_collector.is_split || sgen_concurrent_collection_in_progress (), "Non-pinned objects can only remain in nursery if it is a split nursery");
518 else if (sgen_cement_lookup_or_register (obj))
521 remset.record_pointer (ptr);
523 sgen_pin_stats_register_global_remset (obj);
525 SGEN_LOG (8, "Adding global remset for %p", ptr);
526 binary_protocol_global_remset (ptr, obj, (gpointer)SGEN_LOAD_VTABLE (obj));
530 * sgen_drain_gray_stack:
532 * Scan objects in the gray stack until the stack is empty. This should be called
533 * frequently after each object is copied, to achieve better locality and cache
538 sgen_drain_gray_stack (ScanCopyContext ctx)
540 ScanObjectFunc scan_func = ctx.ops->scan_object;
541 GrayQueue *queue = ctx.queue;
543 if (ctx.ops->drain_gray_stack)
544 return ctx.ops->drain_gray_stack (queue);
549 GRAY_OBJECT_DEQUEUE (queue, &obj, &desc);
552 SGEN_LOG (9, "Precise gray object scan %p (%s)", obj, sgen_client_vtable_get_name (SGEN_LOAD_VTABLE (obj)));
553 scan_func (obj, desc, queue);
559 * Addresses in the pin queue are already sorted. This function finds
560 * the object header for each address and pins the object. The
561 * addresses must be inside the nursery section. The (start of the)
562 * address array is overwritten with the addresses of the actually
563 * pinned objects. Return the number of pinned objects.
566 pin_objects_from_nursery_pin_queue (gboolean do_scan_objects, ScanCopyContext ctx)
568 GCMemSection *section = nursery_section;
569 void **start = sgen_pinning_get_entry (section->pin_queue_first_entry);
570 void **end = sgen_pinning_get_entry (section->pin_queue_last_entry);
571 void *start_nursery = section->data;
572 void *end_nursery = section->next_data;
577 void *pinning_front = start_nursery;
579 void **definitely_pinned = start;
580 ScanObjectFunc scan_func = ctx.ops->scan_object;
581 SgenGrayQueue *queue = ctx.queue;
583 sgen_nursery_allocator_prepare_for_pinning ();
585 while (start < end) {
586 GCObject *obj_to_pin = NULL;
587 size_t obj_to_pin_size = 0;
592 SGEN_ASSERT (0, addr >= start_nursery && addr < end_nursery, "Potential pinning address out of range");
593 SGEN_ASSERT (0, addr >= last, "Pin queue not sorted");
600 SGEN_LOG (5, "Considering pinning addr %p", addr);
601 /* We've already processed everything up to pinning_front. */
602 if (addr < pinning_front) {
608 * Find the closest scan start <= addr. We might search backward in the
609 * scan_starts array because entries might be NULL. In the worst case we
610 * start at start_nursery.
612 idx = ((char*)addr - (char*)section->data) / SCAN_START_SIZE;
613 SGEN_ASSERT (0, idx < section->num_scan_start, "Scan start index out of range");
614 search_start = (void*)section->scan_starts [idx];
615 if (!search_start || search_start > addr) {
618 search_start = section->scan_starts [idx];
619 if (search_start && search_start <= addr)
622 if (!search_start || search_start > addr)
623 search_start = start_nursery;
627 * If the pinning front is closer than the scan start we found, start
628 * searching at the front.
630 if (search_start < pinning_front)
631 search_start = pinning_front;
634 * Now addr should be in an object a short distance from search_start.
636 * search_start must point to zeroed mem or point to an object.
639 size_t obj_size, canarified_obj_size;
642 if (!*(void**)search_start) {
643 search_start = (void*)ALIGN_UP ((mword)search_start + sizeof (gpointer));
644 /* The loop condition makes sure we don't overrun addr. */
648 canarified_obj_size = obj_size = ALIGN_UP (safe_object_get_size ((GCObject*)search_start));
651 * Filler arrays are marked by an invalid sync word. We don't
652 * consider them for pinning. They are not delimited by canaries,
655 if (!sgen_client_object_is_array_fill ((GCObject*)search_start)) {
656 CHECK_CANARY_FOR_OBJECT (search_start, TRUE);
657 CANARIFY_SIZE (canarified_obj_size);
659 if (addr >= search_start && (char*)addr < (char*)search_start + obj_size) {
660 /* This is the object we're looking for. */
661 obj_to_pin = (GCObject*)search_start;
662 obj_to_pin_size = canarified_obj_size;
667 /* Skip to the next object */
668 search_start = (void*)((char*)search_start + canarified_obj_size);
669 } while (search_start <= addr);
671 /* We've searched past the address we were looking for. */
673 pinning_front = search_start;
674 goto next_pin_queue_entry;
678 * We've found an object to pin. It might still be a dummy array, but we
679 * can advance the pinning front in any case.
681 pinning_front = (char*)obj_to_pin + obj_to_pin_size;
684 * If this is a dummy array marking the beginning of a nursery
685 * fragment, we don't pin it.
687 if (sgen_client_object_is_array_fill (obj_to_pin))
688 goto next_pin_queue_entry;
691 * Finally - pin the object!
693 desc = sgen_obj_get_descriptor_safe (obj_to_pin);
694 if (do_scan_objects) {
695 scan_func (obj_to_pin, desc, queue);
697 SGEN_LOG (4, "Pinned object %p, vtable %p (%s), count %d\n",
698 obj_to_pin, *(void**)obj_to_pin, sgen_client_vtable_get_name (SGEN_LOAD_VTABLE (obj_to_pin)), count);
699 binary_protocol_pin (obj_to_pin,
700 (gpointer)LOAD_VTABLE (obj_to_pin),
701 safe_object_get_size (obj_to_pin));
703 pin_object (obj_to_pin);
704 GRAY_OBJECT_ENQUEUE (queue, obj_to_pin, desc);
705 sgen_pin_stats_register_object (obj_to_pin, obj_to_pin_size);
706 definitely_pinned [count] = obj_to_pin;
710 next_pin_queue_entry:
714 sgen_client_nursery_objects_pinned (definitely_pinned, count);
715 stat_pinned_objects += count;
720 pin_objects_in_nursery (gboolean do_scan_objects, ScanCopyContext ctx)
724 if (nursery_section->pin_queue_first_entry == nursery_section->pin_queue_last_entry)
727 reduced_to = pin_objects_from_nursery_pin_queue (do_scan_objects, ctx);
728 nursery_section->pin_queue_last_entry = nursery_section->pin_queue_first_entry + reduced_to;
732 * This function is only ever called (via `collector_pin_object()` in `sgen-copy-object.h`)
733 * when we can't promote an object because we're out of memory.
736 sgen_pin_object (GCObject *object, GrayQueue *queue)
739 * All pinned objects are assumed to have been staged, so we need to stage as well.
740 * Also, the count of staged objects shows that "late pinning" happened.
742 sgen_pin_stage_ptr (object);
744 SGEN_PIN_OBJECT (object);
745 binary_protocol_pin (object, (gpointer)LOAD_VTABLE (object), safe_object_get_size (object));
748 sgen_pin_stats_register_object (object, safe_object_get_size (object));
750 GRAY_OBJECT_ENQUEUE (queue, object, sgen_obj_get_descriptor_safe (object));
753 /* Sort the addresses in array in increasing order.
754 * Done using a by-the book heap sort. Which has decent and stable performance, is pretty cache efficient.
757 sgen_sort_addresses (void **array, size_t size)
762 for (i = 1; i < size; ++i) {
765 size_t parent = (child - 1) / 2;
767 if (array [parent] >= array [child])
770 tmp = array [parent];
771 array [parent] = array [child];
778 for (i = size - 1; i > 0; --i) {
781 array [i] = array [0];
787 while (root * 2 + 1 <= end) {
788 size_t child = root * 2 + 1;
790 if (child < end && array [child] < array [child + 1])
792 if (array [root] >= array [child])
796 array [root] = array [child];
805 * Scan the memory between start and end and queue values which could be pointers
806 * to the area between start_nursery and end_nursery for later consideration.
807 * Typically used for thread stacks.
810 sgen_conservatively_pin_objects_from (void **start, void **end, void *start_nursery, void *end_nursery, int pin_type)
814 SGEN_ASSERT (0, ((mword)start & (SIZEOF_VOID_P - 1)) == 0, "Why are we scanning for references in unaligned memory ?");
816 #if defined(VALGRIND_MAKE_MEM_DEFINED_IF_ADDRESSABLE) && !defined(_WIN64)
817 VALGRIND_MAKE_MEM_DEFINED_IF_ADDRESSABLE (start, (char*)end - (char*)start);
820 while (start < end) {
822 * *start can point to the middle of an object
823 * note: should we handle pointing at the end of an object?
824 * pinning in C# code disallows pointing at the end of an object
825 * but there is some small chance that an optimizing C compiler
826 * may keep the only reference to an object by pointing
827 * at the end of it. We ignore this small chance for now.
828 * Pointers to the end of an object are indistinguishable
829 * from pointers to the start of the next object in memory
830 * so if we allow that we'd need to pin two objects...
831 * We queue the pointer in an array, the
832 * array will then be sorted and uniqued. This way
833 * we can coalesce several pinning pointers and it should
834 * be faster since we'd do a memory scan with increasing
835 * addresses. Note: we can align the address to the allocation
836 * alignment, so the unique process is more effective.
838 mword addr = (mword)*start;
839 addr &= ~(ALLOC_ALIGN - 1);
840 if (addr >= (mword)start_nursery && addr < (mword)end_nursery) {
841 SGEN_LOG (6, "Pinning address %p from %p", (void*)addr, start);
842 sgen_pin_stage_ptr ((void*)addr);
843 binary_protocol_pin_stage (start, (void*)addr);
844 sgen_pin_stats_register_address ((char*)addr, pin_type);
850 SGEN_LOG (7, "found %d potential pinned heap pointers", count);
854 * The first thing we do in a collection is to identify pinned objects.
855 * This function considers all the areas of memory that need to be
856 * conservatively scanned.
859 pin_from_roots (void *start_nursery, void *end_nursery, ScanCopyContext ctx)
863 SGEN_LOG (2, "Scanning pinned roots (%d bytes, %d/%d entries)", (int)roots_size, roots_hash [ROOT_TYPE_NORMAL].num_entries, roots_hash [ROOT_TYPE_PINNED].num_entries);
864 /* objects pinned from the API are inside these roots */
865 SGEN_HASH_TABLE_FOREACH (&roots_hash [ROOT_TYPE_PINNED], void **, start_root, RootRecord *, root) {
866 SGEN_LOG (6, "Pinned roots %p-%p", start_root, root->end_root);
867 sgen_conservatively_pin_objects_from (start_root, (void**)root->end_root, start_nursery, end_nursery, PIN_TYPE_OTHER);
868 } SGEN_HASH_TABLE_FOREACH_END;
869 /* now deal with the thread stacks
870 * in the future we should be able to conservatively scan only:
871 * *) the cpu registers
872 * *) the unmanaged stack frames
873 * *) the _last_ managed stack frame
874 * *) pointers slots in managed frames
876 sgen_client_scan_thread_data (start_nursery, end_nursery, FALSE, ctx);
880 single_arg_user_copy_or_mark (GCObject **obj, void *gc_data)
882 ScanCopyContext *ctx = (ScanCopyContext *)gc_data;
883 ctx->ops->copy_or_mark_object (obj, ctx->queue);
887 * The memory area from start_root to end_root contains pointers to objects.
888 * Their position is precisely described by @desc (this means that the pointer
889 * can be either NULL or the pointer to the start of an object).
890 * This functions copies them to to_space updates them.
892 * This function is not thread-safe!
895 precisely_scan_objects_from (void** start_root, void** end_root, char* n_start, char *n_end, SgenDescriptor desc, ScanCopyContext ctx)
897 CopyOrMarkObjectFunc copy_func = ctx.ops->copy_or_mark_object;
898 SgenGrayQueue *queue = ctx.queue;
900 switch (desc & ROOT_DESC_TYPE_MASK) {
901 case ROOT_DESC_BITMAP:
902 desc >>= ROOT_DESC_TYPE_SHIFT;
904 if ((desc & 1) && *start_root) {
905 copy_func ((GCObject**)start_root, queue);
906 SGEN_LOG (9, "Overwrote root at %p with %p", start_root, *start_root);
912 case ROOT_DESC_COMPLEX: {
913 gsize *bitmap_data = (gsize *)sgen_get_complex_descriptor_bitmap (desc);
914 gsize bwords = (*bitmap_data) - 1;
915 void **start_run = start_root;
917 while (bwords-- > 0) {
918 gsize bmap = *bitmap_data++;
919 void **objptr = start_run;
921 if ((bmap & 1) && *objptr) {
922 copy_func ((GCObject**)objptr, queue);
923 SGEN_LOG (9, "Overwrote root at %p with %p", objptr, *objptr);
928 start_run += GC_BITS_PER_WORD;
932 case ROOT_DESC_USER: {
933 SgenUserRootMarkFunc marker = sgen_get_user_descriptor_func (desc);
934 marker (start_root, single_arg_user_copy_or_mark, &ctx);
937 case ROOT_DESC_RUN_LEN:
938 g_assert_not_reached ();
940 g_assert_not_reached ();
945 reset_heap_boundaries (void)
947 lowest_heap_address = ~(mword)0;
948 highest_heap_address = 0;
952 sgen_update_heap_boundaries (mword low, mword high)
957 old = lowest_heap_address;
960 } while (SGEN_CAS_PTR ((gpointer*)&lowest_heap_address, (gpointer)low, (gpointer)old) != (gpointer)old);
963 old = highest_heap_address;
966 } while (SGEN_CAS_PTR ((gpointer*)&highest_heap_address, (gpointer)high, (gpointer)old) != (gpointer)old);
970 * Allocate and setup the data structures needed to be able to allocate objects
971 * in the nursery. The nursery is stored in nursery_section.
976 GCMemSection *section;
983 SGEN_LOG (2, "Allocating nursery size: %zu", (size_t)sgen_nursery_size);
984 /* later we will alloc a larger area for the nursery but only activate
985 * what we need. The rest will be used as expansion if we have too many pinned
986 * objects in the existing nursery.
988 /* FIXME: handle OOM */
989 section = (GCMemSection *)sgen_alloc_internal (INTERNAL_MEM_SECTION);
991 alloc_size = sgen_nursery_size;
993 /* If there isn't enough space even for the nursery we should simply abort. */
994 g_assert (sgen_memgov_try_alloc_space (alloc_size, SPACE_NURSERY));
996 data = (char *)major_collector.alloc_heap (alloc_size, alloc_size, DEFAULT_NURSERY_BITS);
997 sgen_update_heap_boundaries ((mword)data, (mword)(data + sgen_nursery_size));
998 SGEN_LOG (4, "Expanding nursery size (%p-%p): %lu, total: %lu", data, data + alloc_size, (unsigned long)sgen_nursery_size, (unsigned long)sgen_gc_get_total_heap_allocation ());
999 section->data = section->next_data = data;
1000 section->size = alloc_size;
1001 section->end_data = data + sgen_nursery_size;
1002 scan_starts = (alloc_size + SCAN_START_SIZE - 1) / SCAN_START_SIZE;
1003 section->scan_starts = (char **)sgen_alloc_internal_dynamic (sizeof (char*) * scan_starts, INTERNAL_MEM_SCAN_STARTS, TRUE);
1004 section->num_scan_start = scan_starts;
1006 nursery_section = section;
1008 sgen_nursery_allocator_set_nursery_bounds (data, data + sgen_nursery_size);
1012 mono_gc_get_logfile (void)
1014 return gc_debug_file;
1018 scan_finalizer_entries (SgenPointerQueue *fin_queue, ScanCopyContext ctx)
1020 CopyOrMarkObjectFunc copy_func = ctx.ops->copy_or_mark_object;
1021 SgenGrayQueue *queue = ctx.queue;
1024 for (i = 0; i < fin_queue->next_slot; ++i) {
1025 GCObject *obj = (GCObject *)fin_queue->data [i];
1028 SGEN_LOG (5, "Scan of fin ready object: %p (%s)\n", obj, sgen_client_vtable_get_name (SGEN_LOAD_VTABLE (obj)));
1029 copy_func ((GCObject**)&fin_queue->data [i], queue);
1034 generation_name (int generation)
1036 switch (generation) {
1037 case GENERATION_NURSERY: return "nursery";
1038 case GENERATION_OLD: return "old";
1039 default: g_assert_not_reached ();
1044 sgen_generation_name (int generation)
1046 return generation_name (generation);
1050 finish_gray_stack (int generation, ScanCopyContext ctx)
1054 int done_with_ephemerons, ephemeron_rounds = 0;
1055 char *start_addr = generation == GENERATION_NURSERY ? sgen_get_nursery_start () : NULL;
1056 char *end_addr = generation == GENERATION_NURSERY ? sgen_get_nursery_end () : (char*)-1;
1057 SgenGrayQueue *queue = ctx.queue;
1059 binary_protocol_finish_gray_stack_start (sgen_timestamp (), generation);
1061 * We copied all the reachable objects. Now it's the time to copy
1062 * the objects that were not referenced by the roots, but by the copied objects.
1063 * we built a stack of objects pointed to by gray_start: they are
1064 * additional roots and we may add more items as we go.
1065 * We loop until gray_start == gray_objects which means no more objects have
1066 * been added. Note this is iterative: no recursion is involved.
1067 * We need to walk the LO list as well in search of marked big objects
1068 * (use a flag since this is needed only on major collections). We need to loop
1069 * here as well, so keep a counter of marked LO (increasing it in copy_object).
1070 * To achieve better cache locality and cache usage, we drain the gray stack
1071 * frequently, after each object is copied, and just finish the work here.
1073 sgen_drain_gray_stack (ctx);
1075 SGEN_LOG (2, "%s generation done", generation_name (generation));
1078 Reset bridge data, we might have lingering data from a previous collection if this is a major
1079 collection trigged by minor overflow.
1081 We must reset the gathered bridges since their original block might be evacuated due to major
1082 fragmentation in the meanwhile and the bridge code should not have to deal with that.
1084 if (sgen_client_bridge_need_processing ())
1085 sgen_client_bridge_reset_data ();
1088 * Walk the ephemeron tables marking all values with reachable keys. This must be completely done
1089 * before processing finalizable objects and non-tracking weak links to avoid finalizing/clearing
1090 * objects that are in fact reachable.
1092 done_with_ephemerons = 0;
1094 done_with_ephemerons = sgen_client_mark_ephemerons (ctx);
1095 sgen_drain_gray_stack (ctx);
1097 } while (!done_with_ephemerons);
1099 sgen_client_mark_togglerefs (start_addr, end_addr, ctx);
1101 if (sgen_client_bridge_need_processing ()) {
1102 /*Make sure the gray stack is empty before we process bridge objects so we get liveness right*/
1103 sgen_drain_gray_stack (ctx);
1104 sgen_collect_bridge_objects (generation, ctx);
1105 if (generation == GENERATION_OLD)
1106 sgen_collect_bridge_objects (GENERATION_NURSERY, ctx);
1109 Do the first bridge step here, as the collector liveness state will become useless after that.
1111 An important optimization is to only proccess the possibly dead part of the object graph and skip
1112 over all live objects as we transitively know everything they point must be alive too.
1114 The above invariant is completely wrong if we let the gray queue be drained and mark/copy everything.
1116 This has the unfortunate side effect of making overflow collections perform the first step twice, but
1117 given we now have heuristics that perform major GC in anticipation of minor overflows this should not
1120 sgen_client_bridge_processing_stw_step ();
1124 Make sure we drain the gray stack before processing disappearing links and finalizers.
1125 If we don't make sure it is empty we might wrongly see a live object as dead.
1127 sgen_drain_gray_stack (ctx);
1130 We must clear weak links that don't track resurrection before processing object ready for
1131 finalization so they can be cleared before that.
1133 sgen_null_link_in_range (generation, ctx, FALSE);
1134 if (generation == GENERATION_OLD)
1135 sgen_null_link_in_range (GENERATION_NURSERY, ctx, FALSE);
1138 /* walk the finalization queue and move also the objects that need to be
1139 * finalized: use the finalized objects as new roots so the objects they depend
1140 * on are also not reclaimed. As with the roots above, only objects in the nursery
1141 * are marked/copied.
1143 sgen_finalize_in_range (generation, ctx);
1144 if (generation == GENERATION_OLD)
1145 sgen_finalize_in_range (GENERATION_NURSERY, ctx);
1146 /* drain the new stack that might have been created */
1147 SGEN_LOG (6, "Precise scan of gray area post fin");
1148 sgen_drain_gray_stack (ctx);
1151 * This must be done again after processing finalizable objects since CWL slots are cleared only after the key is finalized.
1153 done_with_ephemerons = 0;
1155 done_with_ephemerons = sgen_client_mark_ephemerons (ctx);
1156 sgen_drain_gray_stack (ctx);
1158 } while (!done_with_ephemerons);
1160 sgen_client_clear_unreachable_ephemerons (ctx);
1163 * We clear togglerefs only after all possible chances of revival are done.
1164 * This is semantically more inline with what users expect and it allows for
1165 * user finalizers to correctly interact with TR objects.
1167 sgen_client_clear_togglerefs (start_addr, end_addr, ctx);
1170 SGEN_LOG (2, "Finalize queue handling scan for %s generation: %ld usecs %d ephemeron rounds", generation_name (generation), TV_ELAPSED (atv, btv), ephemeron_rounds);
1173 * handle disappearing links
1174 * Note we do this after checking the finalization queue because if an object
1175 * survives (at least long enough to be finalized) we don't clear the link.
1176 * This also deals with a possible issue with the monitor reclamation: with the Boehm
1177 * GC a finalized object my lose the monitor because it is cleared before the finalizer is
1180 g_assert (sgen_gray_object_queue_is_empty (queue));
1182 sgen_null_link_in_range (generation, ctx, TRUE);
1183 if (generation == GENERATION_OLD)
1184 sgen_null_link_in_range (GENERATION_NURSERY, ctx, TRUE);
1185 if (sgen_gray_object_queue_is_empty (queue))
1187 sgen_drain_gray_stack (ctx);
1190 g_assert (sgen_gray_object_queue_is_empty (queue));
1192 sgen_gray_object_queue_trim_free_list (queue);
1193 binary_protocol_finish_gray_stack_end (sgen_timestamp (), generation);
1197 sgen_check_section_scan_starts (GCMemSection *section)
1200 for (i = 0; i < section->num_scan_start; ++i) {
1201 if (section->scan_starts [i]) {
1202 mword size = safe_object_get_size ((GCObject*) section->scan_starts [i]);
1203 SGEN_ASSERT (0, size >= SGEN_CLIENT_MINIMUM_OBJECT_SIZE && size <= MAX_SMALL_OBJ_SIZE, "Weird object size at scan starts.");
1209 check_scan_starts (void)
1211 if (!do_scan_starts_check)
1213 sgen_check_section_scan_starts (nursery_section);
1214 major_collector.check_scan_starts ();
1218 scan_from_registered_roots (char *addr_start, char *addr_end, int root_type, ScanCopyContext ctx)
1222 SGEN_HASH_TABLE_FOREACH (&roots_hash [root_type], void **, start_root, RootRecord *, root) {
1223 SGEN_LOG (6, "Precise root scan %p-%p (desc: %p)", start_root, root->end_root, (void*)root->root_desc);
1224 precisely_scan_objects_from (start_root, (void**)root->end_root, addr_start, addr_end, root->root_desc, ctx);
1225 } SGEN_HASH_TABLE_FOREACH_END;
1231 static gboolean inited = FALSE;
1236 mono_counters_register ("Collection max time", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME | MONO_COUNTER_MONOTONIC, &time_max);
1238 mono_counters_register ("Minor fragment clear", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_minor_pre_collection_fragment_clear);
1239 mono_counters_register ("Minor pinning", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_minor_pinning);
1240 mono_counters_register ("Minor scan remembered set", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_minor_scan_remsets);
1241 mono_counters_register ("Minor scan pinned", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_minor_scan_pinned);
1242 mono_counters_register ("Minor scan roots", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_minor_scan_roots);
1243 mono_counters_register ("Minor fragment creation", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_minor_fragment_creation);
1245 mono_counters_register ("Major fragment clear", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_pre_collection_fragment_clear);
1246 mono_counters_register ("Major pinning", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_pinning);
1247 mono_counters_register ("Major scan pinned", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_scan_pinned);
1248 mono_counters_register ("Major scan roots", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_scan_roots);
1249 mono_counters_register ("Major scan mod union", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_scan_mod_union);
1250 mono_counters_register ("Major finish gray stack", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_finish_gray_stack);
1251 mono_counters_register ("Major free big objects", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_free_bigobjs);
1252 mono_counters_register ("Major LOS sweep", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_los_sweep);
1253 mono_counters_register ("Major sweep", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_sweep);
1254 mono_counters_register ("Major fragment creation", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_fragment_creation);
1256 mono_counters_register ("Number of pinned objects", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_pinned_objects);
1258 #ifdef HEAVY_STATISTICS
1259 mono_counters_register ("WBarrier remember pointer", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_wbarrier_add_to_global_remset);
1260 mono_counters_register ("WBarrier arrayref copy", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_wbarrier_arrayref_copy);
1261 mono_counters_register ("WBarrier generic store called", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_wbarrier_generic_store);
1262 mono_counters_register ("WBarrier generic atomic store called", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_wbarrier_generic_store_atomic);
1263 mono_counters_register ("WBarrier set root", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_wbarrier_set_root);
1265 mono_counters_register ("# objects allocated degraded", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_objects_alloced_degraded);
1266 mono_counters_register ("bytes allocated degraded", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_bytes_alloced_degraded);
1268 mono_counters_register ("# copy_object() called (nursery)", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_copy_object_called_nursery);
1269 mono_counters_register ("# objects copied (nursery)", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_objects_copied_nursery);
1270 mono_counters_register ("# copy_object() called (major)", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_copy_object_called_major);
1271 mono_counters_register ("# objects copied (major)", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_objects_copied_major);
1273 mono_counters_register ("# scan_object() called (nursery)", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_scan_object_called_nursery);
1274 mono_counters_register ("# scan_object() called (major)", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_scan_object_called_major);
1276 mono_counters_register ("Slots allocated in vain", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_slots_allocated_in_vain);
1278 mono_counters_register ("# nursery copy_object() failed from space", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_nursery_copy_object_failed_from_space);
1279 mono_counters_register ("# nursery copy_object() failed forwarded", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_nursery_copy_object_failed_forwarded);
1280 mono_counters_register ("# nursery copy_object() failed pinned", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_nursery_copy_object_failed_pinned);
1281 mono_counters_register ("# nursery copy_object() failed to space", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_nursery_copy_object_failed_to_space);
1283 sgen_nursery_allocator_init_heavy_stats ();
1291 reset_pinned_from_failed_allocation (void)
1293 bytes_pinned_from_failed_allocation = 0;
1297 sgen_set_pinned_from_failed_allocation (mword objsize)
1299 bytes_pinned_from_failed_allocation += objsize;
1303 sgen_collection_is_concurrent (void)
1305 switch (current_collection_generation) {
1306 case GENERATION_NURSERY:
1308 case GENERATION_OLD:
1309 return concurrent_collection_in_progress;
1311 g_error ("Invalid current generation %d", current_collection_generation);
1317 sgen_concurrent_collection_in_progress (void)
1319 return concurrent_collection_in_progress;
1323 SgenThreadPoolJob job;
1324 SgenObjectOperations *ops;
1328 job_remembered_set_scan (void *worker_data_untyped, SgenThreadPoolJob *job)
1330 WorkerData *worker_data = (WorkerData *)worker_data_untyped;
1331 ScanJob *job_data = (ScanJob*)job;
1332 ScanCopyContext ctx = CONTEXT_FROM_OBJECT_OPERATIONS (job_data->ops, sgen_workers_get_job_gray_queue (worker_data));
1333 remset.scan_remsets (ctx);
1337 SgenThreadPoolJob job;
1338 SgenObjectOperations *ops;
1342 } ScanFromRegisteredRootsJob;
1345 job_scan_from_registered_roots (void *worker_data_untyped, SgenThreadPoolJob *job)
1347 WorkerData *worker_data = (WorkerData *)worker_data_untyped;
1348 ScanFromRegisteredRootsJob *job_data = (ScanFromRegisteredRootsJob*)job;
1349 ScanCopyContext ctx = CONTEXT_FROM_OBJECT_OPERATIONS (job_data->ops, sgen_workers_get_job_gray_queue (worker_data));
1351 scan_from_registered_roots (job_data->heap_start, job_data->heap_end, job_data->root_type, ctx);
1355 SgenThreadPoolJob job;
1356 SgenObjectOperations *ops;
1359 } ScanThreadDataJob;
1362 job_scan_thread_data (void *worker_data_untyped, SgenThreadPoolJob *job)
1364 WorkerData *worker_data = (WorkerData *)worker_data_untyped;
1365 ScanThreadDataJob *job_data = (ScanThreadDataJob*)job;
1366 ScanCopyContext ctx = CONTEXT_FROM_OBJECT_OPERATIONS (job_data->ops, sgen_workers_get_job_gray_queue (worker_data));
1368 sgen_client_scan_thread_data (job_data->heap_start, job_data->heap_end, TRUE, ctx);
1372 SgenThreadPoolJob job;
1373 SgenObjectOperations *ops;
1374 SgenPointerQueue *queue;
1375 } ScanFinalizerEntriesJob;
1378 job_scan_finalizer_entries (void *worker_data_untyped, SgenThreadPoolJob *job)
1380 WorkerData *worker_data = (WorkerData *)worker_data_untyped;
1381 ScanFinalizerEntriesJob *job_data = (ScanFinalizerEntriesJob*)job;
1382 ScanCopyContext ctx = CONTEXT_FROM_OBJECT_OPERATIONS (job_data->ops, sgen_workers_get_job_gray_queue (worker_data));
1384 scan_finalizer_entries (job_data->queue, ctx);
1388 job_scan_major_mod_union_card_table (void *worker_data_untyped, SgenThreadPoolJob *job)
1390 WorkerData *worker_data = (WorkerData *)worker_data_untyped;
1391 ScanJob *job_data = (ScanJob*)job;
1392 ScanCopyContext ctx = CONTEXT_FROM_OBJECT_OPERATIONS (job_data->ops, sgen_workers_get_job_gray_queue (worker_data));
1394 g_assert (concurrent_collection_in_progress);
1395 major_collector.scan_card_table (CARDTABLE_SCAN_MOD_UNION, ctx);
1399 job_scan_los_mod_union_card_table (void *worker_data_untyped, SgenThreadPoolJob *job)
1401 WorkerData *worker_data = (WorkerData *)worker_data_untyped;
1402 ScanJob *job_data = (ScanJob*)job;
1403 ScanCopyContext ctx = CONTEXT_FROM_OBJECT_OPERATIONS (job_data->ops, sgen_workers_get_job_gray_queue (worker_data));
1405 g_assert (concurrent_collection_in_progress);
1406 sgen_los_scan_card_table (CARDTABLE_SCAN_MOD_UNION, ctx);
1410 job_mod_union_preclean (void *worker_data_untyped, SgenThreadPoolJob *job)
1412 WorkerData *worker_data = (WorkerData *)worker_data_untyped;
1413 ScanJob *job_data = (ScanJob*)job;
1414 ScanCopyContext ctx = CONTEXT_FROM_OBJECT_OPERATIONS (job_data->ops, sgen_workers_get_job_gray_queue (worker_data));
1416 g_assert (concurrent_collection_in_progress);
1418 major_collector.scan_card_table (CARDTABLE_SCAN_MOD_UNION_PRECLEAN, ctx);
1419 sgen_los_scan_card_table (CARDTABLE_SCAN_MOD_UNION_PRECLEAN, ctx);
1423 init_gray_queue (gboolean use_workers)
1426 sgen_workers_init_distribute_gray_queue ();
1427 sgen_gray_object_queue_init (&gray_queue, NULL);
1431 enqueue_scan_from_roots_jobs (char *heap_start, char *heap_end, SgenObjectOperations *ops, gboolean enqueue)
1433 ScanFromRegisteredRootsJob *scrrj;
1434 ScanThreadDataJob *stdj;
1435 ScanFinalizerEntriesJob *sfej;
1437 /* registered roots, this includes static fields */
1439 scrrj = (ScanFromRegisteredRootsJob*)sgen_thread_pool_job_alloc ("scan from registered roots normal", job_scan_from_registered_roots, sizeof (ScanFromRegisteredRootsJob));
1441 scrrj->heap_start = heap_start;
1442 scrrj->heap_end = heap_end;
1443 scrrj->root_type = ROOT_TYPE_NORMAL;
1444 sgen_workers_enqueue_job (&scrrj->job, enqueue);
1446 scrrj = (ScanFromRegisteredRootsJob*)sgen_thread_pool_job_alloc ("scan from registered roots wbarrier", job_scan_from_registered_roots, sizeof (ScanFromRegisteredRootsJob));
1448 scrrj->heap_start = heap_start;
1449 scrrj->heap_end = heap_end;
1450 scrrj->root_type = ROOT_TYPE_WBARRIER;
1451 sgen_workers_enqueue_job (&scrrj->job, enqueue);
1455 stdj = (ScanThreadDataJob*)sgen_thread_pool_job_alloc ("scan thread data", job_scan_thread_data, sizeof (ScanThreadDataJob));
1456 stdj->heap_start = heap_start;
1457 stdj->heap_end = heap_end;
1458 sgen_workers_enqueue_job (&stdj->job, enqueue);
1460 /* Scan the list of objects ready for finalization. */
1462 sfej = (ScanFinalizerEntriesJob*)sgen_thread_pool_job_alloc ("scan finalizer entries", job_scan_finalizer_entries, sizeof (ScanFinalizerEntriesJob));
1463 sfej->queue = &fin_ready_queue;
1465 sgen_workers_enqueue_job (&sfej->job, enqueue);
1467 sfej = (ScanFinalizerEntriesJob*)sgen_thread_pool_job_alloc ("scan critical finalizer entries", job_scan_finalizer_entries, sizeof (ScanFinalizerEntriesJob));
1468 sfej->queue = &critical_fin_queue;
1470 sgen_workers_enqueue_job (&sfej->job, enqueue);
1474 * Perform a nursery collection.
1476 * Return whether any objects were late-pinned due to being out of memory.
1479 collect_nursery (SgenGrayQueue *unpin_queue, gboolean finish_up_concurrent_mark)
1481 gboolean needs_major;
1482 size_t max_garbage_amount;
1484 mword fragment_total;
1486 SgenObjectOperations *object_ops = &sgen_minor_collector.serial_ops;
1487 ScanCopyContext ctx = CONTEXT_FROM_OBJECT_OPERATIONS (object_ops, &gray_queue);
1491 if (disable_minor_collections)
1494 TV_GETTIME (last_minor_collection_start_tv);
1495 atv = last_minor_collection_start_tv;
1497 binary_protocol_collection_begin (gc_stats.minor_gc_count, GENERATION_NURSERY);
1499 if (do_verify_nursery || do_dump_nursery_content)
1500 sgen_debug_verify_nursery (do_dump_nursery_content);
1502 current_collection_generation = GENERATION_NURSERY;
1504 SGEN_ASSERT (0, !sgen_collection_is_concurrent (), "Why is the nursery collection concurrent?");
1506 reset_pinned_from_failed_allocation ();
1508 check_scan_starts ();
1510 sgen_nursery_alloc_prepare_for_minor ();
1514 nursery_next = sgen_nursery_alloc_get_upper_alloc_bound ();
1515 /* FIXME: optimize later to use the higher address where an object can be present */
1516 nursery_next = MAX (nursery_next, sgen_get_nursery_end ());
1518 SGEN_LOG (1, "Start nursery collection %d %p-%p, size: %d", gc_stats.minor_gc_count, sgen_get_nursery_start (), nursery_next, (int)(nursery_next - sgen_get_nursery_start ()));
1519 max_garbage_amount = nursery_next - sgen_get_nursery_start ();
1520 g_assert (nursery_section->size >= max_garbage_amount);
1522 /* world must be stopped already */
1524 time_minor_pre_collection_fragment_clear += TV_ELAPSED (atv, btv);
1526 sgen_client_pre_collection_checks ();
1528 nursery_section->next_data = nursery_next;
1530 major_collector.start_nursery_collection ();
1532 sgen_memgov_minor_collection_start ();
1534 init_gray_queue (FALSE);
1536 gc_stats.minor_gc_count ++;
1538 if (whole_heap_check_before_collection) {
1539 sgen_clear_nursery_fragments ();
1540 sgen_check_whole_heap (finish_up_concurrent_mark);
1542 if (consistency_check_at_minor_collection)
1543 sgen_check_consistency ();
1545 sgen_process_fin_stage_entries ();
1547 /* pin from pinned handles */
1548 sgen_init_pinning ();
1549 sgen_client_binary_protocol_mark_start (GENERATION_NURSERY);
1550 pin_from_roots (sgen_get_nursery_start (), nursery_next, ctx);
1551 /* pin cemented objects */
1552 sgen_pin_cemented_objects ();
1553 /* identify pinned objects */
1554 sgen_optimize_pin_queue ();
1555 sgen_pinning_setup_section (nursery_section);
1557 pin_objects_in_nursery (FALSE, ctx);
1558 sgen_pinning_trim_queue_to_section (nursery_section);
1561 time_minor_pinning += TV_ELAPSED (btv, atv);
1562 SGEN_LOG (2, "Finding pinned pointers: %zd in %ld usecs", sgen_get_pinned_count (), TV_ELAPSED (btv, atv));
1563 SGEN_LOG (4, "Start scan with %zd pinned objects", sgen_get_pinned_count ());
1565 sj = (ScanJob*)sgen_thread_pool_job_alloc ("scan remset", job_remembered_set_scan, sizeof (ScanJob));
1566 sj->ops = object_ops;
1567 sgen_workers_enqueue_job (&sj->job, FALSE);
1569 /* we don't have complete write barrier yet, so we scan all the old generation sections */
1571 time_minor_scan_remsets += TV_ELAPSED (atv, btv);
1572 SGEN_LOG (2, "Old generation scan: %ld usecs", TV_ELAPSED (atv, btv));
1574 sgen_pin_stats_print_class_stats ();
1576 /* FIXME: Why do we do this at this specific, seemingly random, point? */
1577 sgen_client_collecting_minor (&fin_ready_queue, &critical_fin_queue);
1580 time_minor_scan_pinned += TV_ELAPSED (btv, atv);
1582 enqueue_scan_from_roots_jobs (sgen_get_nursery_start (), nursery_next, object_ops, FALSE);
1585 time_minor_scan_roots += TV_ELAPSED (atv, btv);
1587 finish_gray_stack (GENERATION_NURSERY, ctx);
1590 time_minor_finish_gray_stack += TV_ELAPSED (btv, atv);
1591 sgen_client_binary_protocol_mark_end (GENERATION_NURSERY);
1593 if (objects_pinned) {
1594 sgen_optimize_pin_queue ();
1595 sgen_pinning_setup_section (nursery_section);
1598 /* walk the pin_queue, build up the fragment list of free memory, unmark
1599 * pinned objects as we go, memzero() the empty fragments so they are ready for the
1602 sgen_client_binary_protocol_reclaim_start (GENERATION_NURSERY);
1603 fragment_total = sgen_build_nursery_fragments (nursery_section, unpin_queue);
1604 if (!fragment_total)
1607 /* Clear TLABs for all threads */
1608 sgen_clear_tlabs ();
1610 sgen_client_binary_protocol_reclaim_end (GENERATION_NURSERY);
1612 time_minor_fragment_creation += TV_ELAPSED (atv, btv);
1613 SGEN_LOG (2, "Fragment creation: %ld usecs, %lu bytes available", TV_ELAPSED (atv, btv), (unsigned long)fragment_total);
1615 if (consistency_check_at_minor_collection)
1616 sgen_check_major_refs ();
1618 major_collector.finish_nursery_collection ();
1620 TV_GETTIME (last_minor_collection_end_tv);
1621 gc_stats.minor_gc_time += TV_ELAPSED (last_minor_collection_start_tv, last_minor_collection_end_tv);
1623 sgen_debug_dump_heap ("minor", gc_stats.minor_gc_count - 1, NULL);
1625 /* prepare the pin queue for the next collection */
1626 sgen_finish_pinning ();
1627 if (sgen_have_pending_finalizers ()) {
1628 SGEN_LOG (4, "Finalizer-thread wakeup");
1629 sgen_client_finalize_notify ();
1631 sgen_pin_stats_reset ();
1632 /* clear cemented hash */
1633 sgen_cement_clear_below_threshold ();
1635 g_assert (sgen_gray_object_queue_is_empty (&gray_queue));
1637 remset.finish_minor_collection ();
1639 check_scan_starts ();
1641 binary_protocol_flush_buffers (FALSE);
1643 sgen_memgov_minor_collection_end ();
1645 /*objects are late pinned because of lack of memory, so a major is a good call*/
1646 needs_major = objects_pinned > 0;
1647 current_collection_generation = -1;
1650 binary_protocol_collection_end (gc_stats.minor_gc_count - 1, GENERATION_NURSERY, 0, 0);
1652 if (check_nursery_objects_pinned && !sgen_minor_collector.is_split)
1653 sgen_check_nursery_objects_pinned (unpin_queue != NULL);
1659 COPY_OR_MARK_FROM_ROOTS_SERIAL,
1660 COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT,
1661 COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT
1662 } CopyOrMarkFromRootsMode;
1665 major_copy_or_mark_from_roots (size_t *old_next_pin_slot, CopyOrMarkFromRootsMode mode, SgenObjectOperations *object_ops)
1670 /* FIXME: only use these values for the precise scan
1671 * note that to_space pointers should be excluded anyway...
1673 char *heap_start = NULL;
1674 char *heap_end = (char*)-1;
1675 ScanCopyContext ctx = CONTEXT_FROM_OBJECT_OPERATIONS (object_ops, WORKERS_DISTRIBUTE_GRAY_QUEUE);
1676 gboolean concurrent = mode != COPY_OR_MARK_FROM_ROOTS_SERIAL;
1678 SGEN_ASSERT (0, !!concurrent == !!concurrent_collection_in_progress, "We've been called with the wrong mode.");
1680 if (mode == COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT) {
1681 /*This cleans up unused fragments */
1682 sgen_nursery_allocator_prepare_for_pinning ();
1684 if (do_concurrent_checks)
1685 sgen_debug_check_nursery_is_clean ();
1687 /* The concurrent collector doesn't touch the nursery. */
1688 sgen_nursery_alloc_prepare_for_major ();
1691 init_gray_queue (mode == COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT);
1695 /* Pinning depends on this */
1696 sgen_clear_nursery_fragments ();
1698 if (whole_heap_check_before_collection)
1699 sgen_check_whole_heap (mode == COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT);
1702 time_major_pre_collection_fragment_clear += TV_ELAPSED (atv, btv);
1704 if (!sgen_collection_is_concurrent ())
1705 nursery_section->next_data = sgen_get_nursery_end ();
1706 /* we should also coalesce scanning from sections close to each other
1707 * and deal with pointers outside of the sections later.
1712 sgen_client_pre_collection_checks ();
1715 /* Remsets are not useful for a major collection */
1716 remset.clear_cards ();
1719 sgen_process_fin_stage_entries ();
1722 sgen_init_pinning ();
1723 SGEN_LOG (6, "Collecting pinned addresses");
1724 pin_from_roots ((void*)lowest_heap_address, (void*)highest_heap_address, ctx);
1726 sgen_optimize_pin_queue ();
1728 sgen_client_collecting_major_1 ();
1731 * pin_queue now contains all candidate pointers, sorted and
1732 * uniqued. We must do two passes now to figure out which
1733 * objects are pinned.
1735 * The first is to find within the pin_queue the area for each
1736 * section. This requires that the pin_queue be sorted. We
1737 * also process the LOS objects and pinned chunks here.
1739 * The second, destructive, pass is to reduce the section
1740 * areas to pointers to the actually pinned objects.
1742 SGEN_LOG (6, "Pinning from sections");
1743 /* first pass for the sections */
1744 sgen_find_section_pin_queue_start_end (nursery_section);
1745 /* identify possible pointers to the insize of large objects */
1746 SGEN_LOG (6, "Pinning from large objects");
1747 for (bigobj = los_object_list; bigobj; bigobj = bigobj->next) {
1749 if (sgen_find_optimized_pin_queue_area ((char*)bigobj->data, (char*)bigobj->data + sgen_los_object_size (bigobj), &dummy, &dummy)) {
1750 binary_protocol_pin (bigobj->data, (gpointer)LOAD_VTABLE (bigobj->data), safe_object_get_size (bigobj->data));
1752 if (sgen_los_object_is_pinned (bigobj->data)) {
1753 SGEN_ASSERT (0, mode == COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT, "LOS objects can only be pinned here after concurrent marking.");
1756 sgen_los_pin_object (bigobj->data);
1757 if (SGEN_OBJECT_HAS_REFERENCES (bigobj->data))
1758 GRAY_OBJECT_ENQUEUE (WORKERS_DISTRIBUTE_GRAY_QUEUE, bigobj->data, sgen_obj_get_descriptor ((GCObject*)bigobj->data));
1759 sgen_pin_stats_register_object (bigobj->data, safe_object_get_size (bigobj->data));
1760 SGEN_LOG (6, "Marked large object %p (%s) size: %lu from roots", bigobj->data,
1761 sgen_client_vtable_get_name (SGEN_LOAD_VTABLE (bigobj->data)),
1762 (unsigned long)sgen_los_object_size (bigobj));
1764 sgen_client_pinned_los_object (bigobj->data);
1768 pin_objects_in_nursery (mode == COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT, ctx);
1769 if (check_nursery_objects_pinned && !sgen_minor_collector.is_split)
1770 sgen_check_nursery_objects_pinned (mode != COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT);
1772 major_collector.pin_objects (WORKERS_DISTRIBUTE_GRAY_QUEUE);
1773 if (old_next_pin_slot)
1774 *old_next_pin_slot = sgen_get_pinned_count ();
1777 time_major_pinning += TV_ELAPSED (atv, btv);
1778 SGEN_LOG (2, "Finding pinned pointers: %zd in %ld usecs", sgen_get_pinned_count (), TV_ELAPSED (atv, btv));
1779 SGEN_LOG (4, "Start scan with %zd pinned objects", sgen_get_pinned_count ());
1781 major_collector.init_to_space ();
1783 SGEN_ASSERT (0, sgen_workers_all_done (), "Why are the workers not done when we start or finish a major collection?");
1785 * The concurrent collector doesn't move objects, neither on
1786 * the major heap nor in the nursery, so we can mark even
1787 * before pinning has finished. For the non-concurrent
1788 * collector we start the workers after pinning.
1790 if (mode == COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT) {
1792 /* Mod union preclean job */
1793 sj = (ScanJob*)sgen_thread_pool_job_alloc ("preclean mod union cardtable", job_mod_union_preclean, sizeof (ScanJob));
1794 sj->ops = object_ops;
1795 sgen_workers_start_all_workers (object_ops, &sj->job);
1796 gray_queue_enable_redirect (WORKERS_DISTRIBUTE_GRAY_QUEUE);
1797 } else if (mode == COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT) {
1798 if (sgen_workers_have_idle_work ()) {
1799 sgen_workers_start_all_workers (object_ops, NULL);
1800 sgen_workers_join ();
1804 #ifdef SGEN_DEBUG_INTERNAL_ALLOC
1805 main_gc_thread = mono_native_thread_self ();
1808 sgen_client_collecting_major_2 ();
1811 time_major_scan_pinned += TV_ELAPSED (btv, atv);
1813 sgen_client_collecting_major_3 (&fin_ready_queue, &critical_fin_queue);
1816 * FIXME: is this the right context? It doesn't seem to contain a copy function
1817 * unless we're concurrent.
1819 enqueue_scan_from_roots_jobs (heap_start, heap_end, object_ops, mode == COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT);
1822 time_major_scan_roots += TV_ELAPSED (atv, btv);
1824 if (mode == COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT) {
1827 /* Mod union card table */
1828 sj = (ScanJob*)sgen_thread_pool_job_alloc ("scan mod union cardtable", job_scan_major_mod_union_card_table, sizeof (ScanJob));
1829 sj->ops = object_ops;
1830 sgen_workers_enqueue_job (&sj->job, FALSE);
1832 sj = (ScanJob*)sgen_thread_pool_job_alloc ("scan LOS mod union cardtable", job_scan_los_mod_union_card_table, sizeof (ScanJob));
1833 sj->ops = object_ops;
1834 sgen_workers_enqueue_job (&sj->job, FALSE);
1837 time_major_scan_mod_union += TV_ELAPSED (btv, atv);
1840 sgen_pin_stats_print_class_stats ();
1844 major_finish_copy_or_mark (CopyOrMarkFromRootsMode mode)
1846 if (mode == COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT) {
1848 * Prepare the pin queue for the next collection. Since pinning runs on the worker
1849 * threads we must wait for the jobs to finish before we can reset it.
1851 sgen_workers_wait_for_jobs_finished ();
1852 sgen_finish_pinning ();
1854 sgen_pin_stats_reset ();
1856 if (do_concurrent_checks)
1857 sgen_debug_check_nursery_is_clean ();
1862 major_start_collection (gboolean concurrent, size_t *old_next_pin_slot)
1864 SgenObjectOperations *object_ops;
1866 binary_protocol_collection_begin (gc_stats.major_gc_count, GENERATION_OLD);
1868 current_collection_generation = GENERATION_OLD;
1870 g_assert (sgen_section_gray_queue_is_empty (sgen_workers_get_distribute_section_gray_queue ()));
1873 sgen_cement_reset ();
1876 g_assert (major_collector.is_concurrent);
1877 concurrent_collection_in_progress = TRUE;
1879 object_ops = &major_collector.major_ops_concurrent_start;
1881 object_ops = &major_collector.major_ops_serial;
1884 reset_pinned_from_failed_allocation ();
1886 sgen_memgov_major_collection_start ();
1888 //count_ref_nonref_objs ();
1889 //consistency_check ();
1891 check_scan_starts ();
1894 SGEN_LOG (1, "Start major collection %d", gc_stats.major_gc_count);
1895 gc_stats.major_gc_count ++;
1897 if (major_collector.start_major_collection)
1898 major_collector.start_major_collection ();
1900 major_copy_or_mark_from_roots (old_next_pin_slot, concurrent ? COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT : COPY_OR_MARK_FROM_ROOTS_SERIAL, object_ops);
1901 major_finish_copy_or_mark (concurrent ? COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT : COPY_OR_MARK_FROM_ROOTS_SERIAL);
1905 major_finish_collection (const char *reason, size_t old_next_pin_slot, gboolean forced)
1907 ScannedObjectCounts counts;
1908 SgenObjectOperations *object_ops;
1909 mword fragment_total;
1915 if (concurrent_collection_in_progress) {
1916 object_ops = &major_collector.major_ops_concurrent_finish;
1918 major_copy_or_mark_from_roots (NULL, COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT, object_ops);
1920 major_finish_copy_or_mark (COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT);
1922 #ifdef SGEN_DEBUG_INTERNAL_ALLOC
1923 main_gc_thread = NULL;
1926 object_ops = &major_collector.major_ops_serial;
1929 g_assert (sgen_section_gray_queue_is_empty (sgen_workers_get_distribute_section_gray_queue ()));
1931 /* all the objects in the heap */
1932 finish_gray_stack (GENERATION_OLD, CONTEXT_FROM_OBJECT_OPERATIONS (object_ops, &gray_queue));
1934 time_major_finish_gray_stack += TV_ELAPSED (btv, atv);
1936 SGEN_ASSERT (0, sgen_workers_all_done (), "Can't have workers working after joining");
1938 if (objects_pinned) {
1939 g_assert (!concurrent_collection_in_progress);
1942 * This is slow, but we just OOM'd.
1944 * See comment at `sgen_pin_queue_clear_discarded_entries` for how the pin
1945 * queue is laid out at this point.
1947 sgen_pin_queue_clear_discarded_entries (nursery_section, old_next_pin_slot);
1949 * We need to reestablish all pinned nursery objects in the pin queue
1950 * because they're needed for fragment creation. Unpinning happens by
1951 * walking the whole queue, so it's not necessary to reestablish where major
1952 * heap block pins are - all we care is that they're still in there
1955 sgen_optimize_pin_queue ();
1956 sgen_find_section_pin_queue_start_end (nursery_section);
1960 reset_heap_boundaries ();
1961 sgen_update_heap_boundaries ((mword)sgen_get_nursery_start (), (mword)sgen_get_nursery_end ());
1963 /* walk the pin_queue, build up the fragment list of free memory, unmark
1964 * pinned objects as we go, memzero() the empty fragments so they are ready for the
1967 fragment_total = sgen_build_nursery_fragments (nursery_section, NULL);
1968 if (!fragment_total)
1970 SGEN_LOG (4, "Free space in nursery after major %ld", (long)fragment_total);
1972 if (do_concurrent_checks && concurrent_collection_in_progress)
1973 sgen_debug_check_nursery_is_clean ();
1975 /* prepare the pin queue for the next collection */
1976 sgen_finish_pinning ();
1978 /* Clear TLABs for all threads */
1979 sgen_clear_tlabs ();
1981 sgen_pin_stats_reset ();
1983 sgen_cement_clear_below_threshold ();
1985 if (check_mark_bits_after_major_collection)
1986 sgen_check_heap_marked (concurrent_collection_in_progress);
1989 time_major_fragment_creation += TV_ELAPSED (atv, btv);
1991 binary_protocol_sweep_begin (GENERATION_OLD, !major_collector.sweeps_lazily);
1992 sgen_memgov_major_pre_sweep ();
1995 time_major_free_bigobjs += TV_ELAPSED (btv, atv);
2000 time_major_los_sweep += TV_ELAPSED (atv, btv);
2002 major_collector.sweep ();
2004 binary_protocol_sweep_end (GENERATION_OLD, !major_collector.sweeps_lazily);
2007 time_major_sweep += TV_ELAPSED (btv, atv);
2009 sgen_debug_dump_heap ("major", gc_stats.major_gc_count - 1, reason);
2011 if (sgen_have_pending_finalizers ()) {
2012 SGEN_LOG (4, "Finalizer-thread wakeup");
2013 sgen_client_finalize_notify ();
2016 g_assert (sgen_gray_object_queue_is_empty (&gray_queue));
2018 sgen_memgov_major_collection_end (forced);
2019 current_collection_generation = -1;
2021 memset (&counts, 0, sizeof (ScannedObjectCounts));
2022 major_collector.finish_major_collection (&counts);
2024 g_assert (sgen_section_gray_queue_is_empty (sgen_workers_get_distribute_section_gray_queue ()));
2026 SGEN_ASSERT (0, sgen_workers_all_done (), "Can't have workers working after major collection has finished");
2027 if (concurrent_collection_in_progress)
2028 concurrent_collection_in_progress = FALSE;
2030 check_scan_starts ();
2032 binary_protocol_flush_buffers (FALSE);
2034 //consistency_check ();
2036 binary_protocol_collection_end (gc_stats.major_gc_count - 1, GENERATION_OLD, counts.num_scanned_objects, counts.num_unique_scanned_objects);
2040 major_do_collection (const char *reason, gboolean forced)
2042 TV_DECLARE (time_start);
2043 TV_DECLARE (time_end);
2044 size_t old_next_pin_slot;
2046 if (disable_major_collections)
2049 if (major_collector.get_and_reset_num_major_objects_marked) {
2050 long long num_marked = major_collector.get_and_reset_num_major_objects_marked ();
2051 g_assert (!num_marked);
2054 /* world must be stopped already */
2055 TV_GETTIME (time_start);
2057 major_start_collection (FALSE, &old_next_pin_slot);
2058 major_finish_collection (reason, old_next_pin_slot, forced);
2060 TV_GETTIME (time_end);
2061 gc_stats.major_gc_time += TV_ELAPSED (time_start, time_end);
2063 /* FIXME: also report this to the user, preferably in gc-end. */
2064 if (major_collector.get_and_reset_num_major_objects_marked)
2065 major_collector.get_and_reset_num_major_objects_marked ();
2067 return bytes_pinned_from_failed_allocation > 0;
2071 major_start_concurrent_collection (const char *reason)
2073 TV_DECLARE (time_start);
2074 TV_DECLARE (time_end);
2075 long long num_objects_marked;
2077 if (disable_major_collections)
2080 TV_GETTIME (time_start);
2081 SGEN_TV_GETTIME (time_major_conc_collection_start);
2083 num_objects_marked = major_collector.get_and_reset_num_major_objects_marked ();
2084 g_assert (num_objects_marked == 0);
2086 binary_protocol_concurrent_start ();
2088 // FIXME: store reason and pass it when finishing
2089 major_start_collection (TRUE, NULL);
2091 gray_queue_redirect (&gray_queue);
2093 num_objects_marked = major_collector.get_and_reset_num_major_objects_marked ();
2095 TV_GETTIME (time_end);
2096 gc_stats.major_gc_time += TV_ELAPSED (time_start, time_end);
2098 current_collection_generation = -1;
2102 * Returns whether the major collection has finished.
2105 major_should_finish_concurrent_collection (void)
2107 SGEN_ASSERT (0, sgen_gray_object_queue_is_empty (&gray_queue), "Why is the gray queue not empty before we have started doing anything?");
2108 return sgen_workers_all_done ();
2112 major_update_concurrent_collection (void)
2114 TV_DECLARE (total_start);
2115 TV_DECLARE (total_end);
2117 TV_GETTIME (total_start);
2119 binary_protocol_concurrent_update ();
2121 major_collector.update_cardtable_mod_union ();
2122 sgen_los_update_cardtable_mod_union ();
2124 TV_GETTIME (total_end);
2125 gc_stats.major_gc_time += TV_ELAPSED (total_start, total_end);
2129 major_finish_concurrent_collection (gboolean forced)
2131 TV_DECLARE (total_start);
2132 TV_DECLARE (total_end);
2134 TV_GETTIME (total_start);
2136 binary_protocol_concurrent_finish ();
2139 * We need to stop all workers since we're updating the cardtable below.
2140 * The workers will be resumed with a finishing pause context to avoid
2141 * additional cardtable and object scanning.
2143 sgen_workers_stop_all_workers ();
2145 SGEN_TV_GETTIME (time_major_conc_collection_end);
2146 gc_stats.major_gc_time_concurrent += SGEN_TV_ELAPSED (time_major_conc_collection_start, time_major_conc_collection_end);
2148 major_collector.update_cardtable_mod_union ();
2149 sgen_los_update_cardtable_mod_union ();
2151 if (mod_union_consistency_check)
2152 sgen_check_mod_union_consistency ();
2154 current_collection_generation = GENERATION_OLD;
2155 sgen_cement_reset ();
2156 major_finish_collection ("finishing", -1, forced);
2158 if (whole_heap_check_before_collection)
2159 sgen_check_whole_heap (FALSE);
2161 TV_GETTIME (total_end);
2162 gc_stats.major_gc_time += TV_ELAPSED (total_start, total_end) - TV_ELAPSED (last_minor_collection_start_tv, last_minor_collection_end_tv);
2164 current_collection_generation = -1;
2168 * Ensure an allocation request for @size will succeed by freeing enough memory.
2170 * LOCKING: The GC lock MUST be held.
2173 sgen_ensure_free_space (size_t size, int generation)
2175 int generation_to_collect = -1;
2176 const char *reason = NULL;
2178 if (generation == GENERATION_OLD) {
2179 if (sgen_need_major_collection (size)) {
2180 reason = "LOS overflow";
2181 generation_to_collect = GENERATION_OLD;
2184 if (degraded_mode) {
2185 if (sgen_need_major_collection (size)) {
2186 reason = "Degraded mode overflow";
2187 generation_to_collect = GENERATION_OLD;
2189 } else if (sgen_need_major_collection (size)) {
2190 reason = concurrent_collection_in_progress ? "Forced finish concurrent collection" : "Minor allowance";
2191 generation_to_collect = GENERATION_OLD;
2193 generation_to_collect = GENERATION_NURSERY;
2194 reason = "Nursery full";
2198 if (generation_to_collect == -1) {
2199 if (concurrent_collection_in_progress && sgen_workers_all_done ()) {
2200 generation_to_collect = GENERATION_OLD;
2201 reason = "Finish concurrent collection";
2205 if (generation_to_collect == -1)
2207 sgen_perform_collection (size, generation_to_collect, reason, FALSE);
2211 * LOCKING: Assumes the GC lock is held.
2214 sgen_perform_collection (size_t requested_size, int generation_to_collect, const char *reason, gboolean wait_to_finish)
2216 TV_DECLARE (gc_start);
2217 TV_DECLARE (gc_end);
2218 TV_DECLARE (gc_total_start);
2219 TV_DECLARE (gc_total_end);
2220 GGTimingInfo infos [2];
2221 int overflow_generation_to_collect = -1;
2222 int oldest_generation_collected = generation_to_collect;
2223 const char *overflow_reason = NULL;
2225 binary_protocol_collection_requested (generation_to_collect, requested_size, wait_to_finish ? 1 : 0);
2227 SGEN_ASSERT (0, generation_to_collect == GENERATION_NURSERY || generation_to_collect == GENERATION_OLD, "What generation is this?");
2229 TV_GETTIME (gc_start);
2231 sgen_stop_world (generation_to_collect);
2233 TV_GETTIME (gc_total_start);
2235 if (concurrent_collection_in_progress) {
2237 * If the concurrent worker is finished or we are asked to do a major collection
2238 * then we finish the concurrent collection.
2240 gboolean finish = major_should_finish_concurrent_collection () || generation_to_collect == GENERATION_OLD;
2243 major_finish_concurrent_collection (wait_to_finish);
2244 oldest_generation_collected = GENERATION_OLD;
2246 SGEN_ASSERT (0, generation_to_collect == GENERATION_NURSERY, "Why aren't we finishing the concurrent collection?");
2247 major_update_concurrent_collection ();
2248 collect_nursery (NULL, FALSE);
2254 SGEN_ASSERT (0, !concurrent_collection_in_progress, "Why did this not get handled above?");
2257 * There's no concurrent collection in progress. Collect the generation we're asked
2258 * to collect. If the major collector is concurrent and we're not forced to wait,
2259 * start a concurrent collection.
2261 // FIXME: extract overflow reason
2262 if (generation_to_collect == GENERATION_NURSERY) {
2263 if (collect_nursery (NULL, FALSE)) {
2264 overflow_generation_to_collect = GENERATION_OLD;
2265 overflow_reason = "Minor overflow";
2268 if (major_collector.is_concurrent && !wait_to_finish) {
2269 collect_nursery (NULL, FALSE);
2270 major_start_concurrent_collection (reason);
2271 // FIXME: set infos[0] properly
2275 if (major_do_collection (reason, wait_to_finish)) {
2276 overflow_generation_to_collect = GENERATION_NURSERY;
2277 overflow_reason = "Excessive pinning";
2281 TV_GETTIME (gc_end);
2283 memset (infos, 0, sizeof (infos));
2284 infos [0].generation = generation_to_collect;
2285 infos [0].reason = reason;
2286 infos [0].is_overflow = FALSE;
2287 infos [1].generation = -1;
2288 infos [0].total_time = SGEN_TV_ELAPSED (gc_start, gc_end);
2290 SGEN_ASSERT (0, !concurrent_collection_in_progress, "Why did this not get handled above?");
2292 if (overflow_generation_to_collect != -1) {
2294 * We need to do an overflow collection, either because we ran out of memory
2295 * or the nursery is fully pinned.
2298 infos [1].generation = overflow_generation_to_collect;
2299 infos [1].reason = overflow_reason;
2300 infos [1].is_overflow = TRUE;
2303 if (overflow_generation_to_collect == GENERATION_NURSERY)
2304 collect_nursery (NULL, FALSE);
2306 major_do_collection (overflow_reason, wait_to_finish);
2308 TV_GETTIME (gc_end);
2309 infos [1].total_time = SGEN_TV_ELAPSED (gc_start, gc_end);
2311 oldest_generation_collected = MAX (oldest_generation_collected, overflow_generation_to_collect);
2314 SGEN_LOG (2, "Heap size: %lu, LOS size: %lu", (unsigned long)sgen_gc_get_total_heap_allocation (), (unsigned long)los_memory_usage);
2316 /* this also sets the proper pointers for the next allocation */
2317 if (generation_to_collect == GENERATION_NURSERY && !sgen_can_alloc_size (requested_size)) {
2318 /* TypeBuilder and MonoMethod are killing mcs with fragmentation */
2319 SGEN_LOG (1, "nursery collection didn't find enough room for %zd alloc (%zd pinned)", requested_size, sgen_get_pinned_count ());
2320 sgen_dump_pin_queue ();
2325 g_assert (sgen_gray_object_queue_is_empty (&gray_queue));
2327 TV_GETTIME (gc_total_end);
2328 time_max = MAX (time_max, TV_ELAPSED (gc_total_start, gc_total_end));
2330 sgen_restart_world (oldest_generation_collected, infos);
2334 * ######################################################################
2335 * ######## Memory allocation from the OS
2336 * ######################################################################
2337 * This section of code deals with getting memory from the OS and
2338 * allocating memory for GC-internal data structures.
2339 * Internal memory can be handled with a freelist for small objects.
2345 G_GNUC_UNUSED static void
2346 report_internal_mem_usage (void)
2348 printf ("Internal memory usage:\n");
2349 sgen_report_internal_mem_usage ();
2350 printf ("Pinned memory usage:\n");
2351 major_collector.report_pinned_memory_usage ();
2355 * ######################################################################
2356 * ######## Finalization support
2357 * ######################################################################
2361 * If the object has been forwarded it means it's still referenced from a root.
2362 * If it is pinned it's still alive as well.
2363 * A LOS object is only alive if we have pinned it.
2364 * Return TRUE if @obj is ready to be finalized.
2366 static inline gboolean
2367 sgen_is_object_alive (GCObject *object)
2369 if (ptr_in_nursery (object))
2370 return sgen_nursery_is_object_alive (object);
2372 return sgen_major_is_object_alive (object);
2376 * This function returns true if @object is either alive and belongs to the
2377 * current collection - major collections are full heap, so old gen objects
2378 * are never alive during a minor collection.
2381 sgen_is_object_alive_and_on_current_collection (GCObject *object)
2383 if (ptr_in_nursery (object))
2384 return sgen_nursery_is_object_alive (object);
2386 if (current_collection_generation == GENERATION_NURSERY)
2389 return sgen_major_is_object_alive (object);
2394 sgen_gc_is_object_ready_for_finalization (GCObject *object)
2396 return !sgen_is_object_alive (object);
2400 sgen_queue_finalization_entry (GCObject *obj)
2402 gboolean critical = sgen_client_object_has_critical_finalizer (obj);
2404 sgen_pointer_queue_add (critical ? &critical_fin_queue : &fin_ready_queue, obj);
2406 sgen_client_object_queued_for_finalization (obj);
2410 sgen_object_is_live (GCObject *obj)
2412 return sgen_is_object_alive_and_on_current_collection (obj);
2416 * `System.GC.WaitForPendingFinalizers` first checks `sgen_have_pending_finalizers()` to
2417 * determine whether it can exit quickly. The latter must therefore only return FALSE if
2418 * all finalizers have really finished running.
2420 * `sgen_gc_invoke_finalizers()` first dequeues a finalizable object, and then finalizes it.
2421 * This means that just checking whether the queues are empty leaves the possibility that an
2422 * object might have been dequeued but not yet finalized. That's why we need the additional
2423 * flag `pending_unqueued_finalizer`.
2426 static volatile gboolean pending_unqueued_finalizer = FALSE;
2429 sgen_gc_invoke_finalizers (void)
2433 g_assert (!pending_unqueued_finalizer);
2435 /* FIXME: batch to reduce lock contention */
2436 while (sgen_have_pending_finalizers ()) {
2442 * We need to set `pending_unqueued_finalizer` before dequeing the
2443 * finalizable object.
2445 if (!sgen_pointer_queue_is_empty (&fin_ready_queue)) {
2446 pending_unqueued_finalizer = TRUE;
2447 mono_memory_write_barrier ();
2448 obj = (GCObject *)sgen_pointer_queue_pop (&fin_ready_queue);
2449 } else if (!sgen_pointer_queue_is_empty (&critical_fin_queue)) {
2450 pending_unqueued_finalizer = TRUE;
2451 mono_memory_write_barrier ();
2452 obj = (GCObject *)sgen_pointer_queue_pop (&critical_fin_queue);
2458 SGEN_LOG (7, "Finalizing object %p (%s)", obj, sgen_client_vtable_get_name (SGEN_LOAD_VTABLE (obj)));
2466 /* the object is on the stack so it is pinned */
2467 /*g_print ("Calling finalizer for object: %p (%s)\n", obj, sgen_client_object_safe_name (obj));*/
2468 sgen_client_run_finalize (obj);
2471 if (pending_unqueued_finalizer) {
2472 mono_memory_write_barrier ();
2473 pending_unqueued_finalizer = FALSE;
2480 sgen_have_pending_finalizers (void)
2482 return pending_unqueued_finalizer || !sgen_pointer_queue_is_empty (&fin_ready_queue) || !sgen_pointer_queue_is_empty (&critical_fin_queue);
2486 * ######################################################################
2487 * ######## registered roots support
2488 * ######################################################################
2492 * We do not coalesce roots.
2495 sgen_register_root (char *start, size_t size, SgenDescriptor descr, int root_type, int source, const char *msg)
2497 RootRecord new_root;
2500 for (i = 0; i < ROOT_TYPE_NUM; ++i) {
2501 RootRecord *root = (RootRecord *)sgen_hash_table_lookup (&roots_hash [i], start);
2502 /* we allow changing the size and the descriptor (for thread statics etc) */
2504 size_t old_size = root->end_root - start;
2505 root->end_root = start + size;
2506 SGEN_ASSERT (0, !!root->root_desc == !!descr, "Can't change whether a root is precise or conservative.");
2507 SGEN_ASSERT (0, root->source == source, "Can't change a root's source identifier.");
2508 SGEN_ASSERT (0, !!root->msg == !!msg, "Can't change a root's message.");
2509 root->root_desc = descr;
2511 roots_size -= old_size;
2517 new_root.end_root = start + size;
2518 new_root.root_desc = descr;
2519 new_root.source = source;
2522 sgen_hash_table_replace (&roots_hash [root_type], start, &new_root, NULL);
2525 SGEN_LOG (3, "Added root for range: %p-%p, descr: %llx (%d/%d bytes)", start, new_root.end_root, (long long)descr, (int)size, (int)roots_size);
2532 sgen_deregister_root (char* addr)
2538 for (root_type = 0; root_type < ROOT_TYPE_NUM; ++root_type) {
2539 if (sgen_hash_table_remove (&roots_hash [root_type], addr, &root))
2540 roots_size -= (root.end_root - addr);
2546 * ######################################################################
2547 * ######## Thread handling (stop/start code)
2548 * ######################################################################
2552 sgen_get_current_collection_generation (void)
2554 return current_collection_generation;
2558 sgen_thread_register (SgenThreadInfo* info, void *stack_bottom_fallback)
2560 #ifndef HAVE_KW_THREAD
2561 info->tlab_start = info->tlab_next = info->tlab_temp_end = info->tlab_real_end = NULL;
2564 sgen_init_tlab_info (info);
2566 sgen_client_thread_register (info, stack_bottom_fallback);
2572 sgen_thread_unregister (SgenThreadInfo *p)
2574 sgen_client_thread_unregister (p);
2578 * ######################################################################
2579 * ######## Write barriers
2580 * ######################################################################
2584 * Note: the write barriers first do the needed GC work and then do the actual store:
2585 * this way the value is visible to the conservative GC scan after the write barrier
2586 * itself. If a GC interrupts the barrier in the middle, value will be kept alive by
2587 * the conservative scan, otherwise by the remembered set scan.
2591 mono_gc_wbarrier_arrayref_copy (gpointer dest_ptr, gpointer src_ptr, int count)
2593 HEAVY_STAT (++stat_wbarrier_arrayref_copy);
2594 /*This check can be done without taking a lock since dest_ptr array is pinned*/
2595 if (ptr_in_nursery (dest_ptr) || count <= 0) {
2596 mono_gc_memmove_aligned (dest_ptr, src_ptr, count * sizeof (gpointer));
2600 #ifdef SGEN_HEAVY_BINARY_PROTOCOL
2601 if (binary_protocol_is_heavy_enabled ()) {
2603 for (i = 0; i < count; ++i) {
2604 gpointer dest = (gpointer*)dest_ptr + i;
2605 gpointer obj = *((gpointer*)src_ptr + i);
2607 binary_protocol_wbarrier (dest, obj, (gpointer)LOAD_VTABLE (obj));
2612 remset.wbarrier_arrayref_copy (dest_ptr, src_ptr, count);
2616 mono_gc_wbarrier_generic_nostore (gpointer ptr)
2620 HEAVY_STAT (++stat_wbarrier_generic_store);
2622 sgen_client_wbarrier_generic_nostore_check (ptr);
2624 obj = *(gpointer*)ptr;
2626 binary_protocol_wbarrier (ptr, obj, (gpointer)LOAD_VTABLE (obj));
2629 * We need to record old->old pointer locations for the
2630 * concurrent collector.
2632 if (!ptr_in_nursery (obj) && !concurrent_collection_in_progress) {
2633 SGEN_LOG (8, "Skipping remset at %p", ptr);
2637 SGEN_LOG (8, "Adding remset at %p", ptr);
2639 remset.wbarrier_generic_nostore (ptr);
2643 mono_gc_wbarrier_generic_store (gpointer ptr, GCObject* value)
2645 SGEN_LOG (8, "Wbarrier store at %p to %p (%s)", ptr, value, value ? sgen_client_vtable_get_name (SGEN_LOAD_VTABLE (value)) : "null");
2646 SGEN_UPDATE_REFERENCE_ALLOW_NULL (ptr, value);
2647 if (ptr_in_nursery (value) || concurrent_collection_in_progress)
2648 mono_gc_wbarrier_generic_nostore (ptr);
2649 sgen_dummy_use (value);
2652 /* Same as mono_gc_wbarrier_generic_store () but performs the store
2653 * as an atomic operation with release semantics.
2656 mono_gc_wbarrier_generic_store_atomic (gpointer ptr, GCObject *value)
2658 HEAVY_STAT (++stat_wbarrier_generic_store_atomic);
2660 SGEN_LOG (8, "Wbarrier atomic store at %p to %p (%s)", ptr, value, value ? sgen_client_vtable_get_name (SGEN_LOAD_VTABLE (value)) : "null");
2662 InterlockedWritePointer ((volatile gpointer *)ptr, value);
2664 if (ptr_in_nursery (value) || concurrent_collection_in_progress)
2665 mono_gc_wbarrier_generic_nostore (ptr);
2667 sgen_dummy_use (value);
2671 sgen_wbarrier_value_copy_bitmap (gpointer _dest, gpointer _src, int size, unsigned bitmap)
2673 GCObject **dest = (GCObject **)_dest;
2674 GCObject **src = (GCObject **)_src;
2678 mono_gc_wbarrier_generic_store (dest, *src);
2683 size -= SIZEOF_VOID_P;
2689 * ######################################################################
2690 * ######## Other mono public interface functions.
2691 * ######################################################################
2695 sgen_gc_collect (int generation)
2700 sgen_perform_collection (0, generation, "user request", TRUE);
2705 sgen_gc_collection_count (int generation)
2707 if (generation == 0)
2708 return gc_stats.minor_gc_count;
2709 return gc_stats.major_gc_count;
2713 sgen_gc_get_used_size (void)
2717 tot = los_memory_usage;
2718 tot += nursery_section->next_data - nursery_section->data;
2719 tot += major_collector.get_used_size ();
2720 /* FIXME: account for pinned objects */
2726 sgen_env_var_error (const char *env_var, const char *fallback, const char *description_format, ...)
2730 va_start (ap, description_format);
2732 fprintf (stderr, "Warning: In environment variable `%s': ", env_var);
2733 vfprintf (stderr, description_format, ap);
2735 fprintf (stderr, " - %s", fallback);
2736 fprintf (stderr, "\n");
2742 parse_double_in_interval (const char *env_var, const char *opt_name, const char *opt, double min, double max, double *result)
2745 double val = strtod (opt, &endptr);
2746 if (endptr == opt) {
2747 sgen_env_var_error (env_var, "Using default value.", "`%s` must be a number.", opt_name);
2750 else if (val < min || val > max) {
2751 sgen_env_var_error (env_var, "Using default value.", "`%s` must be between %.2f - %.2f.", opt_name, min, max);
2763 char *major_collector_opt = NULL;
2764 char *minor_collector_opt = NULL;
2765 size_t max_heap = 0;
2766 size_t soft_limit = 0;
2768 gboolean debug_print_allowance = FALSE;
2769 double allowance_ratio = 0, save_target = 0;
2770 gboolean cement_enabled = TRUE;
2773 result = InterlockedCompareExchange (&gc_initialized, -1, 0);
2776 /* already inited */
2779 /* being inited by another thread */
2780 mono_thread_info_usleep (1000);
2783 /* we will init it */
2786 g_assert_not_reached ();
2788 } while (result != 0);
2790 SGEN_TV_GETTIME (sgen_init_timestamp);
2792 #ifdef SGEN_WITHOUT_MONO
2793 mono_thread_smr_init ();
2796 mono_coop_mutex_init (&gc_mutex);
2798 gc_debug_file = stderr;
2800 mono_coop_mutex_init (&sgen_interruption_mutex);
2802 if ((env = g_getenv (MONO_GC_PARAMS_NAME))) {
2803 opts = g_strsplit (env, ",", -1);
2804 for (ptr = opts; *ptr; ++ptr) {
2806 if (g_str_has_prefix (opt, "major=")) {
2807 opt = strchr (opt, '=') + 1;
2808 major_collector_opt = g_strdup (opt);
2809 } else if (g_str_has_prefix (opt, "minor=")) {
2810 opt = strchr (opt, '=') + 1;
2811 minor_collector_opt = g_strdup (opt);
2819 sgen_init_internal_allocator ();
2820 sgen_init_nursery_allocator ();
2821 sgen_init_fin_weak_hash ();
2822 sgen_init_hash_table ();
2823 sgen_init_descriptors ();
2824 sgen_init_gray_queues ();
2825 sgen_init_allocator ();
2826 sgen_init_gchandles ();
2828 sgen_register_fixed_internal_mem_type (INTERNAL_MEM_SECTION, SGEN_SIZEOF_GC_MEM_SECTION);
2829 sgen_register_fixed_internal_mem_type (INTERNAL_MEM_GRAY_QUEUE, sizeof (GrayQueueSection));
2831 sgen_client_init ();
2833 if (!minor_collector_opt) {
2834 sgen_simple_nursery_init (&sgen_minor_collector);
2836 if (!strcmp (minor_collector_opt, "simple")) {
2838 sgen_simple_nursery_init (&sgen_minor_collector);
2839 } else if (!strcmp (minor_collector_opt, "split")) {
2840 sgen_split_nursery_init (&sgen_minor_collector);
2842 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Using `simple` instead.", "Unknown minor collector `%s'.", minor_collector_opt);
2843 goto use_simple_nursery;
2847 if (!major_collector_opt || !strcmp (major_collector_opt, "marksweep")) {
2848 use_marksweep_major:
2849 sgen_marksweep_init (&major_collector);
2850 } else if (!major_collector_opt || !strcmp (major_collector_opt, "marksweep-conc")) {
2851 sgen_marksweep_conc_init (&major_collector);
2853 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Using `marksweep` instead.", "Unknown major collector `%s'.", major_collector_opt);
2854 goto use_marksweep_major;
2857 sgen_nursery_size = DEFAULT_NURSERY_SIZE;
2860 gboolean usage_printed = FALSE;
2862 for (ptr = opts; *ptr; ++ptr) {
2864 if (!strcmp (opt, ""))
2866 if (g_str_has_prefix (opt, "major="))
2868 if (g_str_has_prefix (opt, "minor="))
2870 if (g_str_has_prefix (opt, "max-heap-size=")) {
2871 size_t page_size = mono_pagesize ();
2872 size_t max_heap_candidate = 0;
2873 opt = strchr (opt, '=') + 1;
2874 if (*opt && mono_gc_parse_environment_string_extract_number (opt, &max_heap_candidate)) {
2875 max_heap = (max_heap_candidate + page_size - 1) & ~(size_t)(page_size - 1);
2876 if (max_heap != max_heap_candidate)
2877 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Rounding up.", "`max-heap-size` size must be a multiple of %d.", page_size);
2879 sgen_env_var_error (MONO_GC_PARAMS_NAME, NULL, "`max-heap-size` must be an integer.");
2883 if (g_str_has_prefix (opt, "soft-heap-limit=")) {
2884 opt = strchr (opt, '=') + 1;
2885 if (*opt && mono_gc_parse_environment_string_extract_number (opt, &soft_limit)) {
2886 if (soft_limit <= 0) {
2887 sgen_env_var_error (MONO_GC_PARAMS_NAME, NULL, "`soft-heap-limit` must be positive.");
2891 sgen_env_var_error (MONO_GC_PARAMS_NAME, NULL, "`soft-heap-limit` must be an integer.");
2897 if (g_str_has_prefix (opt, "nursery-size=")) {
2899 opt = strchr (opt, '=') + 1;
2900 if (*opt && mono_gc_parse_environment_string_extract_number (opt, &val)) {
2901 if ((val & (val - 1))) {
2902 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Using default value.", "`nursery-size` must be a power of two.");
2906 if (val < SGEN_MAX_NURSERY_WASTE) {
2907 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Using default value.",
2908 "`nursery-size` must be at least %d bytes.", SGEN_MAX_NURSERY_WASTE);
2912 sgen_nursery_size = val;
2913 sgen_nursery_bits = 0;
2914 while (ONE_P << (++ sgen_nursery_bits) != sgen_nursery_size)
2917 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Using default value.", "`nursery-size` must be an integer.");
2923 if (g_str_has_prefix (opt, "save-target-ratio=")) {
2925 opt = strchr (opt, '=') + 1;
2926 if (parse_double_in_interval (MONO_GC_PARAMS_NAME, "save-target-ratio", opt,
2927 SGEN_MIN_SAVE_TARGET_RATIO, SGEN_MAX_SAVE_TARGET_RATIO, &val)) {
2932 if (g_str_has_prefix (opt, "default-allowance-ratio=")) {
2934 opt = strchr (opt, '=') + 1;
2935 if (parse_double_in_interval (MONO_GC_PARAMS_NAME, "default-allowance-ratio", opt,
2936 SGEN_MIN_ALLOWANCE_NURSERY_SIZE_RATIO, SGEN_MIN_ALLOWANCE_NURSERY_SIZE_RATIO, &val)) {
2937 allowance_ratio = val;
2942 if (!strcmp (opt, "cementing")) {
2943 cement_enabled = TRUE;
2946 if (!strcmp (opt, "no-cementing")) {
2947 cement_enabled = FALSE;
2951 if (major_collector.handle_gc_param && major_collector.handle_gc_param (opt))
2954 if (sgen_minor_collector.handle_gc_param && sgen_minor_collector.handle_gc_param (opt))
2957 if (sgen_client_handle_gc_param (opt))
2960 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Ignoring.", "Unknown option `%s`.", opt);
2965 fprintf (stderr, "\n%s must be a comma-delimited list of one or more of the following:\n", MONO_GC_PARAMS_NAME);
2966 fprintf (stderr, " max-heap-size=N (where N is an integer, possibly with a k, m or a g suffix)\n");
2967 fprintf (stderr, " soft-heap-limit=n (where N is an integer, possibly with a k, m or a g suffix)\n");
2968 fprintf (stderr, " nursery-size=N (where N is an integer, possibly with a k, m or a g suffix)\n");
2969 fprintf (stderr, " major=COLLECTOR (where COLLECTOR is `marksweep', `marksweep-conc', `marksweep-par')\n");
2970 fprintf (stderr, " minor=COLLECTOR (where COLLECTOR is `simple' or `split')\n");
2971 fprintf (stderr, " wbarrier=WBARRIER (where WBARRIER is `remset' or `cardtable')\n");
2972 fprintf (stderr, " [no-]cementing\n");
2973 if (major_collector.print_gc_param_usage)
2974 major_collector.print_gc_param_usage ();
2975 if (sgen_minor_collector.print_gc_param_usage)
2976 sgen_minor_collector.print_gc_param_usage ();
2977 sgen_client_print_gc_params_usage ();
2978 fprintf (stderr, " Experimental options:\n");
2979 fprintf (stderr, " save-target-ratio=R (where R must be between %.2f - %.2f).\n", SGEN_MIN_SAVE_TARGET_RATIO, SGEN_MAX_SAVE_TARGET_RATIO);
2980 fprintf (stderr, " default-allowance-ratio=R (where R must be between %.2f - %.2f).\n", SGEN_MIN_ALLOWANCE_NURSERY_SIZE_RATIO, SGEN_MAX_ALLOWANCE_NURSERY_SIZE_RATIO);
2981 fprintf (stderr, "\n");
2983 usage_printed = TRUE;
2988 if (major_collector_opt)
2989 g_free (major_collector_opt);
2991 if (minor_collector_opt)
2992 g_free (minor_collector_opt);
2996 sgen_cement_init (cement_enabled);
2998 if ((env = g_getenv (MONO_GC_DEBUG_NAME))) {
2999 gboolean usage_printed = FALSE;
3001 opts = g_strsplit (env, ",", -1);
3002 for (ptr = opts; ptr && *ptr; ptr ++) {
3004 if (!strcmp (opt, ""))
3006 if (opt [0] >= '0' && opt [0] <= '9') {
3007 gc_debug_level = atoi (opt);
3012 char *rf = g_strdup_printf ("%s.%d", opt, mono_process_current_pid ());
3013 gc_debug_file = fopen (rf, "wb");
3015 gc_debug_file = stderr;
3018 } else if (!strcmp (opt, "print-allowance")) {
3019 debug_print_allowance = TRUE;
3020 } else if (!strcmp (opt, "print-pinning")) {
3021 sgen_pin_stats_enable ();
3022 } else if (!strcmp (opt, "verify-before-allocs")) {
3023 verify_before_allocs = 1;
3024 has_per_allocation_action = TRUE;
3025 } else if (g_str_has_prefix (opt, "verify-before-allocs=")) {
3026 char *arg = strchr (opt, '=') + 1;
3027 verify_before_allocs = atoi (arg);
3028 has_per_allocation_action = TRUE;
3029 } else if (!strcmp (opt, "collect-before-allocs")) {
3030 collect_before_allocs = 1;
3031 has_per_allocation_action = TRUE;
3032 } else if (g_str_has_prefix (opt, "collect-before-allocs=")) {
3033 char *arg = strchr (opt, '=') + 1;
3034 has_per_allocation_action = TRUE;
3035 collect_before_allocs = atoi (arg);
3036 } else if (!strcmp (opt, "verify-before-collections")) {
3037 whole_heap_check_before_collection = TRUE;
3038 } else if (!strcmp (opt, "check-at-minor-collections")) {
3039 consistency_check_at_minor_collection = TRUE;
3040 nursery_clear_policy = CLEAR_AT_GC;
3041 } else if (!strcmp (opt, "mod-union-consistency-check")) {
3042 if (!major_collector.is_concurrent) {
3043 sgen_env_var_error (MONO_GC_DEBUG_NAME, "Ignoring.", "`mod-union-consistency-check` only works with concurrent major collector.");
3046 mod_union_consistency_check = TRUE;
3047 } else if (!strcmp (opt, "check-mark-bits")) {
3048 check_mark_bits_after_major_collection = TRUE;
3049 } else if (!strcmp (opt, "check-nursery-pinned")) {
3050 check_nursery_objects_pinned = TRUE;
3051 } else if (!strcmp (opt, "clear-at-gc")) {
3052 nursery_clear_policy = CLEAR_AT_GC;
3053 } else if (!strcmp (opt, "clear-nursery-at-gc")) {
3054 nursery_clear_policy = CLEAR_AT_GC;
3055 } else if (!strcmp (opt, "clear-at-tlab-creation")) {
3056 nursery_clear_policy = CLEAR_AT_TLAB_CREATION;
3057 } else if (!strcmp (opt, "debug-clear-at-tlab-creation")) {
3058 nursery_clear_policy = CLEAR_AT_TLAB_CREATION_DEBUG;
3059 } else if (!strcmp (opt, "check-scan-starts")) {
3060 do_scan_starts_check = TRUE;
3061 } else if (!strcmp (opt, "verify-nursery-at-minor-gc")) {
3062 do_verify_nursery = TRUE;
3063 } else if (!strcmp (opt, "check-concurrent")) {
3064 if (!major_collector.is_concurrent) {
3065 sgen_env_var_error (MONO_GC_DEBUG_NAME, "Ignoring.", "`check-concurrent` only works with concurrent major collectors.");
3068 nursery_clear_policy = CLEAR_AT_GC;
3069 do_concurrent_checks = TRUE;
3070 } else if (!strcmp (opt, "dump-nursery-at-minor-gc")) {
3071 do_dump_nursery_content = TRUE;
3072 } else if (!strcmp (opt, "disable-minor")) {
3073 disable_minor_collections = TRUE;
3074 } else if (!strcmp (opt, "disable-major")) {
3075 disable_major_collections = TRUE;
3076 } else if (g_str_has_prefix (opt, "heap-dump=")) {
3077 char *filename = strchr (opt, '=') + 1;
3078 nursery_clear_policy = CLEAR_AT_GC;
3079 sgen_debug_enable_heap_dump (filename);
3080 } else if (g_str_has_prefix (opt, "binary-protocol=")) {
3081 char *filename = strchr (opt, '=') + 1;
3082 char *colon = strrchr (filename, ':');
3085 if (!mono_gc_parse_environment_string_extract_number (colon + 1, &limit)) {
3086 sgen_env_var_error (MONO_GC_DEBUG_NAME, "Ignoring limit.", "Binary protocol file size limit must be an integer.");
3091 binary_protocol_init (filename, (long long)limit);
3092 } else if (!strcmp (opt, "nursery-canaries")) {
3093 do_verify_nursery = TRUE;
3094 enable_nursery_canaries = TRUE;
3095 } else if (!sgen_client_handle_gc_debug (opt)) {
3096 sgen_env_var_error (MONO_GC_DEBUG_NAME, "Ignoring.", "Unknown option `%s`.", opt);
3101 fprintf (stderr, "\n%s must be of the format [<l>[:<filename>]|<option>]+ where <l> is a debug level 0-9.\n", MONO_GC_DEBUG_NAME);
3102 fprintf (stderr, "Valid <option>s are:\n");
3103 fprintf (stderr, " collect-before-allocs[=<n>]\n");
3104 fprintf (stderr, " verify-before-allocs[=<n>]\n");
3105 fprintf (stderr, " check-at-minor-collections\n");
3106 fprintf (stderr, " check-mark-bits\n");
3107 fprintf (stderr, " check-nursery-pinned\n");
3108 fprintf (stderr, " verify-before-collections\n");
3109 fprintf (stderr, " verify-nursery-at-minor-gc\n");
3110 fprintf (stderr, " dump-nursery-at-minor-gc\n");
3111 fprintf (stderr, " disable-minor\n");
3112 fprintf (stderr, " disable-major\n");
3113 fprintf (stderr, " check-concurrent\n");
3114 fprintf (stderr, " clear-[nursery-]at-gc\n");
3115 fprintf (stderr, " clear-at-tlab-creation\n");
3116 fprintf (stderr, " debug-clear-at-tlab-creation\n");
3117 fprintf (stderr, " check-scan-starts\n");
3118 fprintf (stderr, " print-allowance\n");
3119 fprintf (stderr, " print-pinning\n");
3120 fprintf (stderr, " heap-dump=<filename>\n");
3121 fprintf (stderr, " binary-protocol=<filename>[:<file-size-limit>]\n");
3122 fprintf (stderr, " nursery-canaries\n");
3123 sgen_client_print_gc_debug_usage ();
3124 fprintf (stderr, "\n");
3126 usage_printed = TRUE;
3132 if (check_mark_bits_after_major_collection)
3133 nursery_clear_policy = CLEAR_AT_GC;
3135 if (major_collector.post_param_init)
3136 major_collector.post_param_init (&major_collector);
3138 if (major_collector.needs_thread_pool)
3139 sgen_workers_init (1);
3141 sgen_memgov_init (max_heap, soft_limit, debug_print_allowance, allowance_ratio, save_target);
3143 memset (&remset, 0, sizeof (remset));
3145 sgen_card_table_init (&remset);
3147 sgen_register_root (NULL, 0, sgen_make_user_root_descriptor (sgen_mark_normal_gc_handles), ROOT_TYPE_NORMAL, MONO_ROOT_SOURCE_GC_HANDLE, "normal gc handles");
3153 sgen_get_nursery_clear_policy (void)
3155 return nursery_clear_policy;
3161 mono_coop_mutex_lock (&gc_mutex);
3165 sgen_gc_unlock (void)
3167 gboolean try_free = sgen_try_free_some_memory;
3168 sgen_try_free_some_memory = FALSE;
3169 mono_coop_mutex_unlock (&gc_mutex);
3171 mono_thread_hazardous_try_free_some ();
3175 sgen_major_collector_iterate_live_block_ranges (sgen_cardtable_block_callback callback)
3177 major_collector.iterate_live_block_ranges (callback);
3181 sgen_get_major_collector (void)
3183 return &major_collector;
3187 sgen_get_remset (void)
3193 count_cards (long long *major_total, long long *major_marked, long long *los_total, long long *los_marked)
3195 sgen_get_major_collector ()->count_cards (major_total, major_marked);
3196 sgen_los_count_cards (los_total, los_marked);
3199 static gboolean world_is_stopped = FALSE;
3201 /* LOCKING: assumes the GC lock is held */
3203 sgen_stop_world (int generation)
3205 long long major_total = -1, major_marked = -1, los_total = -1, los_marked = -1;
3207 SGEN_ASSERT (0, !world_is_stopped, "Why are we stopping a stopped world?");
3209 binary_protocol_world_stopping (generation, sgen_timestamp (), (gpointer) (gsize) mono_native_thread_id_get ());
3211 sgen_client_stop_world (generation);
3213 world_is_stopped = TRUE;
3215 if (binary_protocol_is_heavy_enabled ())
3216 count_cards (&major_total, &major_marked, &los_total, &los_marked);
3217 binary_protocol_world_stopped (generation, sgen_timestamp (), major_total, major_marked, los_total, los_marked);
3220 /* LOCKING: assumes the GC lock is held */
3222 sgen_restart_world (int generation, GGTimingInfo *timing)
3224 long long major_total = -1, major_marked = -1, los_total = -1, los_marked = -1;
3226 SGEN_ASSERT (0, world_is_stopped, "Why are we restarting a running world?");
3228 if (binary_protocol_is_heavy_enabled ())
3229 count_cards (&major_total, &major_marked, &los_total, &los_marked);
3230 binary_protocol_world_restarting (generation, sgen_timestamp (), major_total, major_marked, los_total, los_marked);
3232 sgen_client_restart_world (generation, timing);
3234 world_is_stopped = FALSE;
3236 binary_protocol_world_restarted (generation, sgen_timestamp ());
3238 sgen_try_free_some_memory = TRUE;
3240 if (sgen_client_bridge_need_processing ())
3241 sgen_client_bridge_processing_finish (generation);
3243 sgen_memgov_collection_end (generation, timing, timing ? 2 : 0);
3247 sgen_is_world_stopped (void)
3249 return world_is_stopped;
3253 sgen_check_whole_heap_stw (void)
3255 sgen_stop_world (0);
3256 sgen_clear_nursery_fragments ();
3257 sgen_check_whole_heap (FALSE);
3258 sgen_restart_world (0, NULL);
3262 sgen_timestamp (void)
3264 SGEN_TV_DECLARE (timestamp);
3265 SGEN_TV_GETTIME (timestamp);
3266 return SGEN_TV_ELAPSED (sgen_init_timestamp, timestamp);
3269 #endif /* HAVE_SGEN_GC */