mono/metadata/threadpool-ms.c

   1 /*
   2  * threadpool-ms.c: Microsoft threadpool runtime support
   3  *
   4  * Author:
   5  *      Ludovic Henry (ludovic.henry@xamarin.com)
   6  *
   7  * Copyright 2015 Xamarin, Inc (http://www.xamarin.com)
   8  * Licensed under the MIT license. See LICENSE file in the project root for full license information.
   9  */
  10
  11 //
  12 // Copyright (c) Microsoft. All rights reserved.
  13 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
  14 //
  15 // Files:
  16 //  - src/vm/comthreadpool.cpp
  17 //  - src/vm/win32threadpoolcpp
  18 //  - src/vm/threadpoolrequest.cpp
  19 //  - src/vm/hillclimbing.cpp
  20 //
  21 // Ported from C++ to C and adjusted to Mono runtime
  22
  23 #include <stdlib.h>
  24 #define _USE_MATH_DEFINES // needed by MSVC to define math constants
  25 #include <math.h>
  26 #include <config.h>
  27 #include <glib.h>
  28
  29 #include <mono/metadata/class-internals.h>
  30 #include <mono/metadata/exception.h>
  31 #include <mono/metadata/gc-internals.h>
  32 #include <mono/metadata/object.h>
  33 #include <mono/metadata/object-internals.h>
  34 #include <mono/metadata/threadpool-ms.h>
  35 #include <mono/metadata/threadpool-ms-io.h>
  36 #include <mono/metadata/w32event.h>
  37 #include <mono/utils/atomic.h>
  38 #include <mono/utils/mono-compiler.h>
  39 #include <mono/utils/mono-complex.h>
  40 #include <mono/utils/mono-lazy-init.h>
  41 #include <mono/utils/mono-logger.h>
  42 #include <mono/utils/mono-logger-internals.h>
  43 #include <mono/utils/mono-proclib.h>
  44 #include <mono/utils/mono-threads.h>
  45 #include <mono/utils/mono-time.h>
  46 #include <mono/utils/mono-rand.h>
  47
  48 #define CPU_USAGE_LOW 80
  49 #define CPU_USAGE_HIGH 95
  50
  51 #define MONITOR_INTERVAL 500 // ms
  52 #define MONITOR_MINIMAL_LIFETIME 60 * 1000 // ms
  53
  54 #define WORKER_CREATION_MAX_PER_SEC 10
  55
  56 /* The exponent to apply to the gain. 1.0 means to use linear gain,
  57  * higher values will enhance large moves and damp small ones.
  58  * default: 2.0 */
  59 #define HILL_CLIMBING_GAIN_EXPONENT 2.0
  60
  61 /* The 'cost' of a thread. 0 means drive for increased throughput regardless
  62  * of thread count, higher values bias more against higher thread counts.
  63  * default: 0.15 */
  64 #define HILL_CLIMBING_BIAS 0.15
  65
  66 #define HILL_CLIMBING_WAVE_PERIOD 4
  67 #define HILL_CLIMBING_MAX_WAVE_MAGNITUDE 20
  68 #define HILL_CLIMBING_WAVE_MAGNITUDE_MULTIPLIER 1.0
  69 #define HILL_CLIMBING_WAVE_HISTORY_SIZE 8
  70 #define HILL_CLIMBING_TARGET_SIGNAL_TO_NOISE_RATIO 3.0
  71 #define HILL_CLIMBING_MAX_CHANGE_PER_SECOND 4
  72 #define HILL_CLIMBING_MAX_CHANGE_PER_SAMPLE 20
  73 #define HILL_CLIMBING_SAMPLE_INTERVAL_LOW 10
  74 #define HILL_CLIMBING_SAMPLE_INTERVAL_HIGH 200
  75 #define HILL_CLIMBING_ERROR_SMOOTHING_FACTOR 0.01
  76 #define HILL_CLIMBING_MAX_SAMPLE_ERROR_PERCENT 0.15
  77
  78 typedef union {
  79         struct {
  80                 gint16 max_working; /* determined by heuristic */
  81                 gint16 active; /* executing worker_thread */
  82                 gint16 working; /* actively executing worker_thread, not parked */
  83                 gint16 parked; /* parked */
  84         } _;
  85         gint64 as_gint64;
  86 } ThreadPoolCounter;
  87
  88 typedef struct {
  89         MonoDomain *domain;
  90         gint32 outstanding_request;
  91 } ThreadPoolDomain;
  92
  93 typedef MonoInternalThread ThreadPoolWorkingThread;
  94
  95 typedef struct {
  96         gint32 wave_period;
  97         gint32 samples_to_measure;
  98         gdouble target_throughput_ratio;
  99         gdouble target_signal_to_noise_ratio;
 100         gdouble max_change_per_second;
 101         gdouble max_change_per_sample;
 102         gint32 max_thread_wave_magnitude;
 103         gint32 sample_interval_low;
 104         gdouble thread_magnitude_multiplier;
 105         gint32 sample_interval_high;
 106         gdouble throughput_error_smoothing_factor;
 107         gdouble gain_exponent;
 108         gdouble max_sample_error;
 109
 110         gdouble current_control_setting;
 111         gint64 total_samples;
 112         gint16 last_thread_count;
 113         gdouble elapsed_since_last_change;
 114         gdouble completions_since_last_change;
 115
 116         gdouble average_throughput_noise;
 117
 118         gdouble *samples;
 119         gdouble *thread_counts;
 120
 121         guint32 current_sample_interval;
 122         gpointer random_interval_generator;
 123
 124         gint32 accumulated_completion_count;
 125         gdouble accumulated_sample_duration;
 126 } ThreadPoolHillClimbing;
 127
 128 typedef struct {
 129         ThreadPoolCounter counters;
 130
 131         GPtrArray *domains; // ThreadPoolDomain* []
 132         MonoCoopMutex domains_lock;
 133
 134         GPtrArray *working_threads; // ThreadPoolWorkingThread* []
 135         gint32 parked_threads_count;
 136         MonoCoopCond parked_threads_cond;
 137         MonoCoopMutex active_threads_lock; /* protect access to working_threads and parked_threads */
 138
 139         guint32 worker_creation_current_second;
 140         guint32 worker_creation_current_count;
 141         MonoCoopMutex worker_creation_lock;
 142
 143         gint32 heuristic_completions;
 144         gint64 heuristic_sample_start;
 145         gint64 heuristic_last_dequeue; // ms
 146         gint64 heuristic_last_adjustment; // ms
 147         gint64 heuristic_adjustment_interval; // ms
 148         ThreadPoolHillClimbing heuristic_hill_climbing;
 149         MonoCoopMutex heuristic_lock;
 150
 151         gint32 limit_worker_min;
 152         gint32 limit_worker_max;
 153         gint32 limit_io_min;
 154         gint32 limit_io_max;
 155
 156         MonoCpuUsageState *cpu_usage_state;
 157         gint32 cpu_usage;
 158
 159         /* suspended by the debugger */
 160         gboolean suspended;
 161 } ThreadPool;
 162
 163 typedef struct {
 164         gint32 ref;
 165         MonoCoopSem sem;
 166 } ThreadPoolDomainCleanupSemaphore;
 167
 168 typedef enum {
 169         TRANSITION_WARMUP,
 170         TRANSITION_INITIALIZING,
 171         TRANSITION_RANDOM_MOVE,
 172         TRANSITION_CLIMBING_MOVE,
 173         TRANSITION_CHANGE_POINT,
 174         TRANSITION_STABILIZING,
 175         TRANSITION_STARVATION,
 176         TRANSITION_THREAD_TIMED_OUT,
 177         TRANSITION_UNDEFINED,
 178 } ThreadPoolHeuristicStateTransition;
 179
 180 static mono_lazy_init_t status = MONO_LAZY_INIT_STATUS_NOT_INITIALIZED;
 181
 182 enum {
 183         MONITOR_STATUS_REQUESTED,
 184         MONITOR_STATUS_WAITING_FOR_REQUEST,
 185         MONITOR_STATUS_NOT_RUNNING,
 186 };
 187
 188 static gint32 monitor_status = MONITOR_STATUS_NOT_RUNNING;
 189
 190 static ThreadPool* threadpool;
 191
 192 #define COUNTER_CHECK(counter) \
 193         do { \
 194                 g_assert (counter._.max_working > 0); \
 195                 g_assert (counter._.working >= 0); \
 196                 g_assert (counter._.active >= 0); \
 197         } while (0)
 198
 199 #define COUNTER_READ() (InterlockedRead64 (&threadpool->counters.as_gint64))
 200
 201 #define COUNTER_ATOMIC(var,block) \
 202         do { \
 203                 ThreadPoolCounter __old; \
 204                 do { \
 205                         g_assert (threadpool); \
 206                         __old.as_gint64 = COUNTER_READ (); \
 207                         (var) = __old; \
 208                         { block; } \
 209                         COUNTER_CHECK (var); \
 210                 } while (InterlockedCompareExchange64 (&threadpool->counters.as_gint64, (var).as_gint64, __old.as_gint64) != __old.as_gint64); \
 211         } while (0)
 212
 213 #define COUNTER_TRY_ATOMIC(res,var,block) \
 214         do { \
 215                 ThreadPoolCounter __old; \
 216                 do { \
 217                         g_assert (threadpool); \
 218                         __old.as_gint64 = COUNTER_READ (); \
 219                         (var) = __old; \
 220                         (res) = FALSE; \
 221                         { block; } \
 222                         COUNTER_CHECK (var); \
 223                         (res) = InterlockedCompareExchange64 (&threadpool->counters.as_gint64, (var).as_gint64, __old.as_gint64) == __old.as_gint64; \
 224                 } while (0); \
 225         } while (0)
 226
 227 static gpointer
 228 rand_create (void)
 229 {
 230         mono_rand_open ();
 231         return mono_rand_init (NULL, 0);
 232 }
 233
 234 static guint32
 235 rand_next (gpointer *handle, guint32 min, guint32 max)
 236 {
 237         MonoError error;
 238         guint32 val;
 239         mono_rand_try_get_uint32 (handle, &val, min, max, &error);
 240         // FIXME handle error
 241         mono_error_assert_ok (&error);
 242         return val;
 243 }
 244
 245 static void
 246 rand_free (gpointer handle)
 247 {
 248         mono_rand_close (handle);
 249 }
 250
 251 static void
 252 initialize (void)
 253 {
 254         ThreadPoolHillClimbing *hc;
 255         const char *threads_per_cpu_env;
 256         gint threads_per_cpu;
 257         gint threads_count;
 258
 259         g_assert (!threadpool);
 260         threadpool = g_new0 (ThreadPool, 1);
 261         g_assert (threadpool);
 262
 263         threadpool->domains = g_ptr_array_new ();
 264         mono_coop_mutex_init (&threadpool->domains_lock);
 265
 266         threadpool->parked_threads_count = 0;
 267         mono_coop_cond_init (&threadpool->parked_threads_cond);
 268         threadpool->working_threads = g_ptr_array_new ();
 269         mono_coop_mutex_init (&threadpool->active_threads_lock);
 270
 271         threadpool->worker_creation_current_second = -1;
 272         mono_coop_mutex_init (&threadpool->worker_creation_lock);
 273
 274         threadpool->heuristic_adjustment_interval = 10;
 275         mono_coop_mutex_init (&threadpool->heuristic_lock);
 276
 277         mono_rand_open ();
 278
 279         hc = &threadpool->heuristic_hill_climbing;
 280
 281         hc->wave_period = HILL_CLIMBING_WAVE_PERIOD;
 282         hc->max_thread_wave_magnitude = HILL_CLIMBING_MAX_WAVE_MAGNITUDE;
 283         hc->thread_magnitude_multiplier = (gdouble) HILL_CLIMBING_WAVE_MAGNITUDE_MULTIPLIER;
 284         hc->samples_to_measure = hc->wave_period * HILL_CLIMBING_WAVE_HISTORY_SIZE;
 285         hc->target_throughput_ratio = (gdouble) HILL_CLIMBING_BIAS;
 286         hc->target_signal_to_noise_ratio = (gdouble) HILL_CLIMBING_TARGET_SIGNAL_TO_NOISE_RATIO;
 287         hc->max_change_per_second = (gdouble) HILL_CLIMBING_MAX_CHANGE_PER_SECOND;
 288         hc->max_change_per_sample = (gdouble) HILL_CLIMBING_MAX_CHANGE_PER_SAMPLE;
 289         hc->sample_interval_low = HILL_CLIMBING_SAMPLE_INTERVAL_LOW;
 290         hc->sample_interval_high = HILL_CLIMBING_SAMPLE_INTERVAL_HIGH;
 291         hc->throughput_error_smoothing_factor = (gdouble) HILL_CLIMBING_ERROR_SMOOTHING_FACTOR;
 292         hc->gain_exponent = (gdouble) HILL_CLIMBING_GAIN_EXPONENT;
 293         hc->max_sample_error = (gdouble) HILL_CLIMBING_MAX_SAMPLE_ERROR_PERCENT;
 294         hc->current_control_setting = 0;
 295         hc->total_samples = 0;
 296         hc->last_thread_count = 0;
 297         hc->average_throughput_noise = 0;
 298         hc->elapsed_since_last_change = 0;
 299         hc->accumulated_completion_count = 0;
 300         hc->accumulated_sample_duration = 0;
 301         hc->samples = g_new0 (gdouble, hc->samples_to_measure);
 302         hc->thread_counts = g_new0 (gdouble, hc->samples_to_measure);
 303         hc->random_interval_generator = rand_create ();
 304         hc->current_sample_interval = rand_next (&hc->random_interval_generator, hc->sample_interval_low, hc->sample_interval_high);
 305
 306         if (!(threads_per_cpu_env = g_getenv ("MONO_THREADS_PER_CPU")))
 307                 threads_per_cpu = 1;
 308         else
 309                 threads_per_cpu = CLAMP (atoi (threads_per_cpu_env), 1, 50);
 310
 311         threads_count = mono_cpu_count () * threads_per_cpu;
 312
 313         threadpool->limit_worker_min = threadpool->limit_io_min = threads_count;
 314
 315 #if defined (PLATFORM_ANDROID) || defined (HOST_IOS)
 316         threadpool->limit_worker_max = threadpool->limit_io_max = CLAMP (threads_count * 100, MIN (threads_count, 200), MAX (threads_count, 200));
 317 #else
 318         threadpool->limit_worker_max = threadpool->limit_io_max = threads_count * 100;
 319 #endif
 320
 321         threadpool->counters._.max_working = threadpool->limit_worker_min;
 322
 323         threadpool->cpu_usage_state = g_new0 (MonoCpuUsageState, 1);
 324
 325         threadpool->suspended = FALSE;
 326 }
 327
 328 static void worker_kill (ThreadPoolWorkingThread *thread);
 329
 330 static void
 331 cleanup (void)
 332 {
 333         guint i;
 334
 335         /* we make the assumption along the code that we are
 336          * cleaning up only if the runtime is shutting down */
 337         g_assert (mono_runtime_is_shutting_down ());
 338
 339         while (monitor_status != MONITOR_STATUS_NOT_RUNNING)
 340                 mono_thread_info_sleep (1, NULL);
 341
 342         mono_coop_mutex_lock (&threadpool->active_threads_lock);
 343
 344         /* stop all threadpool->working_threads */
 345         for (i = 0; i < threadpool->working_threads->len; ++i)
 346                 worker_kill ((ThreadPoolWorkingThread*) g_ptr_array_index (threadpool->working_threads, i));
 347
 348         /* unpark all threadpool->parked_threads */
 349         mono_coop_cond_broadcast (&threadpool->parked_threads_cond);
 350
 351         mono_coop_mutex_unlock (&threadpool->active_threads_lock);
 352 }
 353
 354 gboolean
 355 mono_threadpool_ms_enqueue_work_item (MonoDomain *domain, MonoObject *work_item, MonoError *error)
 356 {
 357         static MonoClass *threadpool_class = NULL;
 358         static MonoMethod *unsafe_queue_custom_work_item_method = NULL;
 359         MonoDomain *current_domain;
 360         MonoBoolean f;
 361         gpointer args [2];
 362
 363         mono_error_init (error);
 364         g_assert (work_item);
 365
 366         if (!threadpool_class)
 367                 threadpool_class = mono_class_load_from_name (mono_defaults.corlib, "System.Threading", "ThreadPool");
 368
 369         if (!unsafe_queue_custom_work_item_method)
 370                 unsafe_queue_custom_work_item_method = mono_class_get_method_from_name (threadpool_class, "UnsafeQueueCustomWorkItem", 2);
 371         g_assert (unsafe_queue_custom_work_item_method);
 372
 373         f = FALSE;
 374
 375         args [0] = (gpointer) work_item;
 376         args [1] = (gpointer) &f;
 377
 378         current_domain = mono_domain_get ();
 379         if (current_domain == domain) {
 380                 mono_runtime_invoke_checked (unsafe_queue_custom_work_item_method, NULL, args, error);
 381                 return_val_if_nok (error, FALSE);
 382         } else {
 383                 mono_thread_push_appdomain_ref (domain);
 384                 if (mono_domain_set (domain, FALSE)) {
 385                         mono_runtime_invoke_checked (unsafe_queue_custom_work_item_method, NULL, args, error);
 386                         if (!is_ok (error)) {
 387                                 mono_thread_pop_appdomain_ref ();
 388                                 return FALSE;
 389                         }
 390                         mono_domain_set (current_domain, TRUE);
 391                 }
 392                 mono_thread_pop_appdomain_ref ();
 393         }
 394         return TRUE;
 395 }
 396
 397 /* LOCKING: threadpool->domains_lock must be held */
 398 static void
 399 domain_add (ThreadPoolDomain *tpdomain)
 400 {
 401         guint i, len;
 402
 403         g_assert (tpdomain);
 404
 405         len = threadpool->domains->len;
 406         for (i = 0; i < len; ++i) {
 407                 if (g_ptr_array_index (threadpool->domains, i) == tpdomain)
 408                         break;
 409         }
 410
 411         if (i == len)
 412                 g_ptr_array_add (threadpool->domains, tpdomain);
 413 }
 414
 415 /* LOCKING: threadpool->domains_lock must be held */
 416 static gboolean
 417 domain_remove (ThreadPoolDomain *tpdomain)
 418 {
 419         g_assert (tpdomain);
 420         return g_ptr_array_remove (threadpool->domains, tpdomain);
 421 }
 422
 423 /* LOCKING: threadpool->domains_lock must be held */
 424 static ThreadPoolDomain *
 425 domain_get (MonoDomain *domain, gboolean create)
 426 {
 427         ThreadPoolDomain *tpdomain = NULL;
 428         guint i;
 429
 430         g_assert (domain);
 431
 432         for (i = 0; i < threadpool->domains->len; ++i) {
 433                 tpdomain = (ThreadPoolDomain *)g_ptr_array_index (threadpool->domains, i);
 434                 if (tpdomain->domain == domain)
 435                         return tpdomain;
 436         }
 437
 438         if (create) {
 439                 ThreadPoolDomainCleanupSemaphore *cleanup_semaphore;
 440                 cleanup_semaphore = g_new0 (ThreadPoolDomainCleanupSemaphore, 1);
 441                 cleanup_semaphore->ref = 2;
 442                 mono_coop_sem_init (&cleanup_semaphore->sem, 0);
 443
 444                 g_assert(!domain->cleanup_semaphore);
 445                 domain->cleanup_semaphore = cleanup_semaphore;
 446
 447                 tpdomain = g_new0 (ThreadPoolDomain, 1);
 448                 tpdomain->domain = domain;
 449                 domain_add (tpdomain);
 450         }
 451
 452         return tpdomain;
 453 }
 454
 455 static void
 456 domain_free (ThreadPoolDomain *tpdomain)
 457 {
 458         g_free (tpdomain);
 459 }
 460
 461 /* LOCKING: threadpool->domains_lock must be held */
 462 static gboolean
 463 domain_any_has_request (void)
 464 {
 465         guint i;
 466
 467         for (i = 0; i < threadpool->domains->len; ++i) {
 468                 ThreadPoolDomain *tmp = (ThreadPoolDomain *)g_ptr_array_index (threadpool->domains, i);
 469                 if (tmp->outstanding_request > 0)
 470                         return TRUE;
 471         }
 472
 473         return FALSE;
 474 }
 475
 476 /* LOCKING: threadpool->domains_lock must be held */
 477 static ThreadPoolDomain *
 478 domain_get_next (ThreadPoolDomain *current)
 479 {
 480         ThreadPoolDomain *tpdomain = NULL;
 481         guint len;
 482
 483         len = threadpool->domains->len;
 484         if (len > 0) {
 485                 guint i, current_idx = -1;
 486                 if (current) {
 487                         for (i = 0; i < len; ++i) {
 488                                 if (current == g_ptr_array_index (threadpool->domains, i)) {
 489                                         current_idx = i;
 490                                         break;
 491                                 }
 492                         }
 493                         g_assert (current_idx != (guint)-1);
 494                 }
 495                 for (i = current_idx + 1; i < len + current_idx + 1; ++i) {
 496                         ThreadPoolDomain *tmp = (ThreadPoolDomain *)g_ptr_array_index (threadpool->domains, i % len);
 497                         if (tmp->outstanding_request > 0) {
 498                                 tpdomain = tmp;
 499                                 break;
 500                         }
 501                 }
 502         }
 503
 504         return tpdomain;
 505 }
 506
 507 static void
 508 worker_wait_interrupt (gpointer data)
 509 {
 510         mono_coop_mutex_lock (&threadpool->active_threads_lock);
 511         mono_coop_cond_signal (&threadpool->parked_threads_cond);
 512         mono_coop_mutex_unlock (&threadpool->active_threads_lock);
 513 }
 514
 515 /* return TRUE if timeout, FALSE otherwise (worker unpark or interrupt) */
 516 static gboolean
 517 worker_park (void)
 518 {
 519         gboolean timeout = FALSE;
 520
 521         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] current worker parking", mono_native_thread_id_get ());
 522
 523         mono_gc_set_skip_thread (TRUE);
 524
 525         mono_coop_mutex_lock (&threadpool->active_threads_lock);
 526
 527         if (!mono_runtime_is_shutting_down ()) {
 528                 static gpointer rand_handle = NULL;
 529                 MonoInternalThread *thread_internal;
 530                 gboolean interrupted = FALSE;
 531
 532                 if (!rand_handle)
 533                         rand_handle = rand_create ();
 534                 g_assert (rand_handle);
 535
 536                 thread_internal = mono_thread_internal_current ();
 537                 g_assert (thread_internal);
 538
 539                 threadpool->parked_threads_count += 1;
 540                 g_ptr_array_remove_fast (threadpool->working_threads, thread_internal);
 541
 542                 mono_thread_info_install_interrupt (worker_wait_interrupt, NULL, &interrupted);
 543                 if (interrupted)
 544                         goto done;
 545
 546                 if (mono_coop_cond_timedwait (&threadpool->parked_threads_cond, &threadpool->active_threads_lock, rand_next (&rand_handle, 5 * 1000, 60 * 1000)) != 0)
 547                         timeout = TRUE;
 548
 549                 mono_thread_info_uninstall_interrupt (&interrupted);
 550
 551 done:
 552                 g_ptr_array_add (threadpool->working_threads, thread_internal);
 553                 threadpool->parked_threads_count -= 1;
 554         }
 555
 556         mono_coop_mutex_unlock (&threadpool->active_threads_lock);
 557
 558         mono_gc_set_skip_thread (FALSE);
 559
 560         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] current worker unparking, timeout? %s", mono_native_thread_id_get (), timeout ? "yes" : "no");
 561
 562         return timeout;
 563 }
 564
 565 static gboolean
 566 worker_try_unpark (void)
 567 {
 568         gboolean res = FALSE;
 569
 570         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] try unpark worker", mono_native_thread_id_get ());
 571
 572         mono_coop_mutex_lock (&threadpool->active_threads_lock);
 573         if (threadpool->parked_threads_count > 0) {
 574                 mono_coop_cond_signal (&threadpool->parked_threads_cond);
 575                 res = TRUE;
 576         }
 577         mono_coop_mutex_unlock (&threadpool->active_threads_lock);
 578
 579         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] try unpark worker, success? %s", mono_native_thread_id_get (), res ? "yes" : "no");
 580
 581         return res;
 582 }
 583
 584 static void
 585 worker_kill (ThreadPoolWorkingThread *thread)
 586 {
 587         if (thread == mono_thread_internal_current ())
 588                 return;
 589
 590         mono_thread_internal_stop ((MonoInternalThread*) thread);
 591 }
 592
 593 static void
 594 worker_thread (gpointer data)
 595 {
 596         MonoError error;
 597         MonoInternalThread *thread;
 598         ThreadPoolDomain *tpdomain, *previous_tpdomain;
 599         ThreadPoolCounter counter;
 600         gboolean retire = FALSE;
 601
 602         mono_trace (G_LOG_LEVEL_INFO, MONO_TRACE_THREADPOOL, "[%p] worker starting", mono_native_thread_id_get ());
 603
 604         g_assert (threadpool);
 605
 606         thread = mono_thread_internal_current ();
 607         g_assert (thread);
 608
 609         mono_thread_set_name_internal (thread, mono_string_new (mono_get_root_domain (), "Threadpool worker"), FALSE, &error);
 610         mono_error_assert_ok (&error);
 611
 612         mono_coop_mutex_lock (&threadpool->active_threads_lock);
 613         g_ptr_array_add (threadpool->working_threads, thread);
 614         mono_coop_mutex_unlock (&threadpool->active_threads_lock);
 615
 616         previous_tpdomain = NULL;
 617
 618         mono_coop_mutex_lock (&threadpool->domains_lock);
 619
 620         while (!mono_runtime_is_shutting_down ()) {
 621                 tpdomain = NULL;
 622
 623                 if ((thread->state & (ThreadState_StopRequested | ThreadState_SuspendRequested)) != 0) {
 624                         mono_coop_mutex_unlock (&threadpool->domains_lock);
 625                         mono_thread_interruption_checkpoint ();
 626                         mono_coop_mutex_lock (&threadpool->domains_lock);
 627                 }
 628
 629                 if (retire || !(tpdomain = domain_get_next (previous_tpdomain))) {
 630                         gboolean timeout;
 631
 632                         COUNTER_ATOMIC (counter, {
 633                                 counter._.working --;
 634                                 counter._.parked ++;
 635                         });
 636
 637                         mono_coop_mutex_unlock (&threadpool->domains_lock);
 638                         timeout = worker_park ();
 639                         mono_coop_mutex_lock (&threadpool->domains_lock);
 640
 641                         COUNTER_ATOMIC (counter, {
 642                                 counter._.working ++;
 643                                 counter._.parked --;
 644                         });
 645
 646                         if (timeout)
 647                                 break;
 648
 649                         if (retire)
 650                                 retire = FALSE;
 651
 652                         /* The tpdomain->domain might have unloaded, while this thread was parked */
 653                         previous_tpdomain = NULL;
 654
 655                         continue;
 656                 }
 657
 658                 tpdomain->outstanding_request --;
 659                 g_assert (tpdomain->outstanding_request >= 0);
 660
 661                 mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] worker running in domain %p",
 662                         mono_native_thread_id_get (), tpdomain->domain, tpdomain->outstanding_request);
 663
 664                 g_assert (tpdomain->domain);
 665                 g_assert (tpdomain->domain->threadpool_jobs >= 0);
 666                 tpdomain->domain->threadpool_jobs ++;
 667
 668                 mono_coop_mutex_unlock (&threadpool->domains_lock);
 669
 670                 mono_thread_push_appdomain_ref (tpdomain->domain);
 671                 if (mono_domain_set (tpdomain->domain, FALSE)) {
 672                         MonoObject *exc = NULL, *res;
 673
 674                         res = mono_runtime_try_invoke (mono_defaults.threadpool_perform_wait_callback_method, NULL, NULL, &exc, &error);
 675                         if (exc || !mono_error_ok(&error)) {
 676                                 if (exc == NULL)
 677                                         exc = (MonoObject *) mono_error_convert_to_exception (&error);
 678                                 else
 679                                         mono_error_cleanup (&error);
 680                                 mono_thread_internal_unhandled_exception (exc);
 681                         } else if (res && *(MonoBoolean*) mono_object_unbox (res) == FALSE)
 682                                 retire = TRUE;
 683
 684                         mono_thread_clr_state (thread, (MonoThreadState)~ThreadState_Background);
 685                         if (!mono_thread_test_state (thread , ThreadState_Background))
 686                                 ves_icall_System_Threading_Thread_SetState (thread, ThreadState_Background);
 687
 688                         mono_domain_set (mono_get_root_domain (), TRUE);
 689                 }
 690                 mono_thread_pop_appdomain_ref ();
 691
 692                 mono_coop_mutex_lock (&threadpool->domains_lock);
 693
 694                 tpdomain->domain->threadpool_jobs --;
 695                 g_assert (tpdomain->domain->threadpool_jobs >= 0);
 696
 697                 if (tpdomain->domain->threadpool_jobs == 0 && mono_domain_is_unloading (tpdomain->domain)) {
 698                         ThreadPoolDomainCleanupSemaphore *cleanup_semaphore;
 699                         gboolean removed;
 700
 701                         removed = domain_remove(tpdomain);
 702                         g_assert (removed);
 703
 704                         cleanup_semaphore = (ThreadPoolDomainCleanupSemaphore*) tpdomain->domain->cleanup_semaphore;
 705
 706                         g_assert(cleanup_semaphore);
 707                         mono_coop_sem_post (&cleanup_semaphore->sem);
 708                         if (InterlockedDecrement (&cleanup_semaphore->ref) == 0) {
 709                                 mono_coop_sem_destroy (&cleanup_semaphore->sem);
 710                                 g_free (cleanup_semaphore);
 711                                 tpdomain->domain->cleanup_semaphore = NULL;
 712                         }
 713
 714                         domain_free (tpdomain);
 715                         tpdomain = NULL;
 716                 }
 717
 718                 previous_tpdomain = tpdomain;
 719         }
 720
 721         mono_coop_mutex_unlock (&threadpool->domains_lock);
 722
 723         mono_coop_mutex_lock (&threadpool->active_threads_lock);
 724         g_ptr_array_remove_fast (threadpool->working_threads, thread);
 725         mono_coop_mutex_unlock (&threadpool->active_threads_lock);
 726
 727         COUNTER_ATOMIC (counter, {
 728                 counter._.working--;
 729                 counter._.active --;
 730         });
 731
 732         mono_trace (G_LOG_LEVEL_INFO, MONO_TRACE_THREADPOOL, "[%p] worker finishing", mono_native_thread_id_get ());
 733 }
 734
 735 static gboolean
 736 worker_try_create (void)
 737 {
 738         ThreadPoolCounter counter;
 739         MonoInternalThread *thread;
 740         gint64 current_ticks;
 741         gint32 now;
 742
 743         mono_coop_mutex_lock (&threadpool->worker_creation_lock);
 744
 745         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] try create worker", mono_native_thread_id_get ());
 746         current_ticks = mono_100ns_ticks ();
 747         now = current_ticks / (10 * 1000 * 1000);
 748         if (0 == current_ticks) {
 749                 g_warning ("failed to get 100ns ticks");
 750         } else {
 751                 if (threadpool->worker_creation_current_second != now) {
 752                         threadpool->worker_creation_current_second = now;
 753                         threadpool->worker_creation_current_count = 0;
 754                 } else {
 755                         g_assert (threadpool->worker_creation_current_count <= WORKER_CREATION_MAX_PER_SEC);
 756                         if (threadpool->worker_creation_current_count == WORKER_CREATION_MAX_PER_SEC) {
 757                                 mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] try create worker, failed: maximum number of worker created per second reached, current count = %d",
 758                                         mono_native_thread_id_get (), threadpool->worker_creation_current_count);
 759                                 mono_coop_mutex_unlock (&threadpool->worker_creation_lock);
 760                                 return FALSE;
 761                         }
 762                 }
 763         }
 764
 765         COUNTER_ATOMIC (counter, {
 766                 if (counter._.working >= counter._.max_working) {
 767                         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] try create worker, failed: maximum number of working threads reached",
 768                                 mono_native_thread_id_get ());
 769                         mono_coop_mutex_unlock (&threadpool->worker_creation_lock);
 770                         return FALSE;
 771                 }
 772                 counter._.working ++;
 773                 counter._.active ++;
 774         });
 775
 776         MonoError error;
 777         if ((thread = mono_thread_create_internal (mono_get_root_domain (), worker_thread, NULL, TRUE, 0, &error)) != NULL) {
 778                 threadpool->worker_creation_current_count += 1;
 779
 780                 mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] try create worker, created %p, now = %d count = %d", mono_native_thread_id_get (), thread->tid, now, threadpool->worker_creation_current_count);
 781                 mono_coop_mutex_unlock (&threadpool->worker_creation_lock);
 782                 return TRUE;
 783         }
 784
 785         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] try create worker, failed: could not create thread due to %s", mono_native_thread_id_get (), mono_error_get_message (&error));
 786         mono_error_cleanup (&error);
 787
 788         COUNTER_ATOMIC (counter, {
 789                 counter._.working --;
 790                 counter._.active --;
 791         });
 792
 793         mono_coop_mutex_unlock (&threadpool->worker_creation_lock);
 794         return FALSE;
 795 }
 796
 797 static void monitor_ensure_running (void);
 798
 799 static gboolean
 800 worker_request (MonoDomain *domain)
 801 {
 802         ThreadPoolDomain *tpdomain;
 803
 804         g_assert (domain);
 805         g_assert (threadpool);
 806
 807         if (mono_runtime_is_shutting_down ())
 808                 return FALSE;
 809
 810         mono_coop_mutex_lock (&threadpool->domains_lock);
 811
 812         /* synchronize check with worker_thread */
 813         if (mono_domain_is_unloading (domain)) {
 814                 mono_coop_mutex_unlock (&threadpool->domains_lock);
 815                 return FALSE;
 816         }
 817
 818         tpdomain = domain_get (domain, TRUE);
 819         g_assert (tpdomain);
 820         tpdomain->outstanding_request ++;
 821
 822         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] request worker, domain = %p, outstanding_request = %d",
 823                 mono_native_thread_id_get (), tpdomain->domain, tpdomain->outstanding_request);
 824
 825         mono_coop_mutex_unlock (&threadpool->domains_lock);
 826
 827         if (threadpool->suspended)
 828                 return FALSE;
 829
 830         monitor_ensure_running ();
 831
 832         if (worker_try_unpark ()) {
 833                 mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] request worker, unparked", mono_native_thread_id_get ());
 834                 return TRUE;
 835         }
 836
 837         if (worker_try_create ()) {
 838                 mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] request worker, created", mono_native_thread_id_get ());
 839                 return TRUE;
 840         }
 841
 842         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] request worker, failed", mono_native_thread_id_get ());
 843         return FALSE;
 844 }
 845
 846 static gboolean
 847 monitor_should_keep_running (void)
 848 {
 849         static gint64 last_should_keep_running = -1;
 850
 851         g_assert (monitor_status == MONITOR_STATUS_WAITING_FOR_REQUEST || monitor_status == MONITOR_STATUS_REQUESTED);
 852
 853         if (InterlockedExchange (&monitor_status, MONITOR_STATUS_WAITING_FOR_REQUEST) == MONITOR_STATUS_WAITING_FOR_REQUEST) {
 854                 gboolean should_keep_running = TRUE, force_should_keep_running = FALSE;
 855
 856                 if (mono_runtime_is_shutting_down ()) {
 857                         should_keep_running = FALSE;
 858                 } else {
 859                         mono_coop_mutex_lock (&threadpool->domains_lock);
 860                         if (!domain_any_has_request ())
 861                                 should_keep_running = FALSE;
 862                         mono_coop_mutex_unlock (&threadpool->domains_lock);
 863
 864                         if (!should_keep_running) {
 865                                 if (last_should_keep_running == -1 || mono_100ns_ticks () - last_should_keep_running < MONITOR_MINIMAL_LIFETIME * 1000 * 10) {
 866                                         should_keep_running = force_should_keep_running = TRUE;
 867                                 }
 868                         }
 869                 }
 870
 871                 if (should_keep_running) {
 872                         if (last_should_keep_running == -1 || !force_should_keep_running)
 873                                 last_should_keep_running = mono_100ns_ticks ();
 874                 } else {
 875                         last_should_keep_running = -1;
 876                         if (InterlockedCompareExchange (&monitor_status, MONITOR_STATUS_NOT_RUNNING, MONITOR_STATUS_WAITING_FOR_REQUEST) == MONITOR_STATUS_WAITING_FOR_REQUEST)
 877                                 return FALSE;
 878                 }
 879         }
 880
 881         g_assert (monitor_status == MONITOR_STATUS_WAITING_FOR_REQUEST || monitor_status == MONITOR_STATUS_REQUESTED);
 882
 883         return TRUE;
 884 }
 885
 886 static gboolean
 887 monitor_sufficient_delay_since_last_dequeue (void)
 888 {
 889         gint64 threshold;
 890
 891         g_assert (threadpool);
 892
 893         if (threadpool->cpu_usage < CPU_USAGE_LOW) {
 894                 threshold = MONITOR_INTERVAL;
 895         } else {
 896                 ThreadPoolCounter counter;
 897                 counter.as_gint64 = COUNTER_READ();
 898                 threshold = counter._.max_working * MONITOR_INTERVAL * 2;
 899         }
 900
 901         return mono_msec_ticks () >= threadpool->heuristic_last_dequeue + threshold;
 902 }
 903
 904 static void hill_climbing_force_change (gint16 new_thread_count, ThreadPoolHeuristicStateTransition transition);
 905
 906 static void
 907 monitor_thread (void)
 908 {
 909         MonoInternalThread *current_thread = mono_thread_internal_current ();
 910         guint i;
 911
 912         mono_cpu_usage (threadpool->cpu_usage_state);
 913
 914         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] monitor thread, started", mono_native_thread_id_get ());
 915
 916         do {
 917                 ThreadPoolCounter counter;
 918                 gboolean limit_worker_max_reached;
 919                 gint32 interval_left = MONITOR_INTERVAL;
 920                 gint32 awake = 0; /* number of spurious awakes we tolerate before doing a round of rebalancing */
 921
 922                 g_assert (monitor_status != MONITOR_STATUS_NOT_RUNNING);
 923
 924                 mono_gc_set_skip_thread (TRUE);
 925
 926                 do {
 927                         gint64 ts;
 928                         gboolean alerted = FALSE;
 929
 930                         if (mono_runtime_is_shutting_down ())
 931                                 break;
 932
 933                         ts = mono_msec_ticks ();
 934                         if (mono_thread_info_sleep (interval_left, &alerted) == 0)
 935                                 break;
 936                         interval_left -= mono_msec_ticks () - ts;
 937
 938                         mono_gc_set_skip_thread (FALSE);
 939                         if ((current_thread->state & (ThreadState_StopRequested | ThreadState_SuspendRequested)) != 0)
 940                                 mono_thread_interruption_checkpoint ();
 941                         mono_gc_set_skip_thread (TRUE);
 942                 } while (interval_left > 0 && ++awake < 10);
 943
 944                 mono_gc_set_skip_thread (FALSE);
 945
 946                 if (threadpool->suspended)
 947                         continue;
 948
 949                 if (mono_runtime_is_shutting_down ())
 950                         continue;
 951
 952                 mono_coop_mutex_lock (&threadpool->domains_lock);
 953                 if (!domain_any_has_request ()) {
 954                         mono_coop_mutex_unlock (&threadpool->domains_lock);
 955                         continue;
 956                 }
 957                 mono_coop_mutex_unlock (&threadpool->domains_lock);
 958
 959                 threadpool->cpu_usage = mono_cpu_usage (threadpool->cpu_usage_state);
 960
 961                 if (!monitor_sufficient_delay_since_last_dequeue ())
 962                         continue;
 963
 964                 limit_worker_max_reached = FALSE;
 965
 966                 COUNTER_ATOMIC (counter, {
 967                         if (counter._.max_working >= threadpool->limit_worker_max) {
 968                                 limit_worker_max_reached = TRUE;
 969                                 break;
 970                         }
 971                         counter._.max_working ++;
 972                 });
 973
 974                 if (limit_worker_max_reached)
 975                         continue;
 976
 977                 hill_climbing_force_change (counter._.max_working, TRANSITION_STARVATION);
 978
 979                 for (i = 0; i < 5; ++i) {
 980                         if (mono_runtime_is_shutting_down ())
 981                                 break;
 982
 983                         if (worker_try_unpark ()) {
 984                                 mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] monitor thread, unparked", mono_native_thread_id_get ());
 985                                 break;
 986                         }
 987
 988                         if (worker_try_create ()) {
 989                                 mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] monitor thread, created", mono_native_thread_id_get ());
 990                                 break;
 991                         }
 992                 }
 993         } while (monitor_should_keep_running ());
 994
 995         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_THREADPOOL, "[%p] monitor thread, finished", mono_native_thread_id_get ());
 996 }
 997
 998 static void
 999 monitor_ensure_running (void)
1000 {
1001         MonoError error;
1002         for (;;) {
1003                 switch (monitor_status) {
1004                 case MONITOR_STATUS_REQUESTED:
1005                         return;
1006                 case MONITOR_STATUS_WAITING_FOR_REQUEST:
1007                         InterlockedCompareExchange (&monitor_status, MONITOR_STATUS_REQUESTED, MONITOR_STATUS_WAITING_FOR_REQUEST);
1008                         break;
1009                 case MONITOR_STATUS_NOT_RUNNING:
1010                         if (mono_runtime_is_shutting_down ())
1011                                 return;
1012                         if (InterlockedCompareExchange (&monitor_status, MONITOR_STATUS_REQUESTED, MONITOR_STATUS_NOT_RUNNING) == MONITOR_STATUS_NOT_RUNNING) {
1013                                 if (!mono_thread_create_internal (mono_get_root_domain (), monitor_thread, NULL, TRUE, SMALL_STACK, &error)) {
1014                                         monitor_status = MONITOR_STATUS_NOT_RUNNING;
1015                                         mono_error_cleanup (&error);
1016                                 }
1017                                 return;
1018                         }
1019                         break;
1020                 default: g_assert_not_reached ();
1021                 }
1022         }
1023 }
1024
1025 static void
1026 hill_climbing_change_thread_count (gint16 new_thread_count, ThreadPoolHeuristicStateTransition transition)
1027 {
1028         ThreadPoolHillClimbing *hc;
1029
1030         g_assert (threadpool);
1031
1032         hc = &threadpool->heuristic_hill_climbing;
1033
1034         mono_trace (G_LOG_LEVEL_INFO, MONO_TRACE_THREADPOOL, "[%p] hill climbing, change max number of threads %d", mono_native_thread_id_get (), new_thread_count);
1035
1036         hc->last_thread_count = new_thread_count;
1037         hc->current_sample_interval = rand_next (&hc->random_interval_generator, hc->sample_interval_low, hc->sample_interval_high);
1038         hc->elapsed_since_last_change = 0;
1039         hc->completions_since_last_change = 0;
1040 }
1041
1042 static void
1043 hill_climbing_force_change (gint16 new_thread_count, ThreadPoolHeuristicStateTransition transition)
1044 {
1045         ThreadPoolHillClimbing *hc;
1046
1047         g_assert (threadpool);
1048
1049         hc = &threadpool->heuristic_hill_climbing;
1050
1051         if (new_thread_count != hc->last_thread_count) {
1052                 hc->current_control_setting += new_thread_count - hc->last_thread_count;
1053                 hill_climbing_change_thread_count (new_thread_count, transition);
1054         }
1055 }
1056
1057 static double_complex
1058 hill_climbing_get_wave_component (gdouble *samples, guint sample_count, gdouble period)
1059 {
1060         ThreadPoolHillClimbing *hc;
1061         gdouble w, cosine, sine, coeff, q0, q1, q2;
1062         guint i;
1063
1064         g_assert (threadpool);
1065         g_assert (sample_count >= period);
1066         g_assert (period >= 2);
1067
1068         hc = &threadpool->heuristic_hill_climbing;
1069
1070         w = 2.0 * M_PI / period;
1071         cosine = cos (w);
1072         sine = sin (w);
1073         coeff = 2.0 * cosine;
1074         q0 = q1 = q2 = 0;
1075
1076         for (i = 0; i < sample_count; ++i) {
1077                 q0 = coeff * q1 - q2 + samples [(hc->total_samples - sample_count + i) % hc->samples_to_measure];
1078                 q2 = q1;
1079                 q1 = q0;
1080         }
1081
1082         return mono_double_complex_scalar_div (mono_double_complex_make (q1 - q2 * cosine, (q2 * sine)), ((gdouble)sample_count));
1083 }
1084
1085 static gint16
1086 hill_climbing_update (gint16 current_thread_count, guint32 sample_duration, gint32 completions, gint64 *adjustment_interval)
1087 {
1088         ThreadPoolHillClimbing *hc;
1089         ThreadPoolHeuristicStateTransition transition;
1090         gdouble throughput;
1091         gdouble throughput_error_estimate;
1092         gdouble confidence;
1093         gdouble move;
1094         gdouble gain;
1095         gint sample_index;
1096         gint sample_count;
1097         gint new_thread_wave_magnitude;
1098         gint new_thread_count;
1099         double_complex thread_wave_component;
1100         double_complex throughput_wave_component;
1101         double_complex ratio;
1102
1103         g_assert (threadpool);
1104         g_assert (adjustment_interval);
1105
1106         hc = &threadpool->heuristic_hill_climbing;
1107
1108         /* If someone changed the thread count without telling us, update our records accordingly. */
1109         if (current_thread_count != hc->last_thread_count)
1110                 hill_climbing_force_change (current_thread_count, TRANSITION_INITIALIZING);
1111
1112         /* Update the cumulative stats for this thread count */
1113         hc->elapsed_since_last_change += sample_duration;
1114         hc->completions_since_last_change += completions;
1115
1116         /* Add in any data we've already collected about this sample */
1117         sample_duration += hc->accumulated_sample_duration;
1118         completions += hc->accumulated_completion_count;
1119
1120         /* We need to make sure we're collecting reasonably accurate data. Since we're just counting the end
1121          * of each work item, we are goinng to be missing some data about what really happened during the
1122          * sample interval. The count produced by each thread includes an initial work item that may have
1123          * started well before the start of the interval, and each thread may have been running some new
1124          * work item for some time before the end of the interval, which did not yet get counted. So
1125          * our count is going to be off by +/- threadCount workitems.
1126          *
1127          * The exception is that the thread that reported to us last time definitely wasn't running any work
1128          * at that time, and the thread that's reporting now definitely isn't running a work item now. So
1129          * we really only need to consider threadCount-1 threads.
1130          *
1131          * Thus the percent error in our count is +/- (threadCount-1)/numCompletions.
1132          *
1133          * We cannot rely on the frequency-domain analysis we'll be doing later to filter out this error, because
1134          * of the way it accumulates over time. If this sample is off by, say, 33% in the negative direction,
1135          * then the next one likely will be too. The one after that will include the sum of the completions
1136          * we missed in the previous samples, and so will be 33% positive. So every three samples we'll have
1137          * two "low" samples and one "high" sample. This will appear as periodic variation right in the frequency
1138          * range we're targeting, which will not be filtered by the frequency-domain translation. */
1139         if (hc->total_samples > 0 && ((current_thread_count - 1.0) / completions) >= hc->max_sample_error) {
1140                 /* Not accurate enough yet. Let's accumulate the data so
1141                  * far, and tell the ThreadPool to collect a little more. */
1142                 hc->accumulated_sample_duration = sample_duration;
1143                 hc->accumulated_completion_count = completions;
1144                 *adjustment_interval = 10;
1145                 return current_thread_count;
1146         }
1147
1148         /* We've got enouugh data for our sample; reset our accumulators for next time. */
1149         hc->accumulated_sample_duration = 0;
1150         hc->accumulated_completion_count = 0;
1151
1152         /* Add the current thread count and throughput sample to our history. */
1153         throughput = ((gdouble) completions) / sample_duration;
1154
1155         sample_index = hc->total_samples % hc->samples_to_measure;
1156         hc->samples [sample_index] = throughput;
1157         hc->thread_counts [sample_index] = current_thread_count;
1158         hc->total_samples ++;
1159
1160         /* Set up defaults for our metrics. */
1161         thread_wave_component = mono_double_complex_make(0, 0);
1162         throughput_wave_component = mono_double_complex_make(0, 0);
1163         throughput_error_estimate = 0;
1164         ratio = mono_double_complex_make(0, 0);
1165         confidence = 0;
1166
1167         transition = TRANSITION_WARMUP;
1168
1169         /* How many samples will we use? It must be at least the three wave periods we're looking for, and it must also
1170          * be a whole multiple of the primary wave's period; otherwise the frequency we're looking for will fall between
1171          * two frequency bands in the Fourier analysis, and we won't be able to measure it accurately. */
1172         sample_count = ((gint) MIN (hc->total_samples - 1, hc->samples_to_measure) / hc->wave_period) * hc->wave_period;
1173
1174         if (sample_count > hc->wave_period) {
1175                 guint i;
1176                 gdouble average_throughput;
1177                 gdouble average_thread_count;
1178                 gdouble sample_sum = 0;
1179                 gdouble thread_sum = 0;
1180
1181                 /* Average the throughput and thread count samples, so we can scale the wave magnitudes later. */
1182                 for (i = 0; i < sample_count; ++i) {
1183                         guint j = (hc->total_samples - sample_count + i) % hc->samples_to_measure;
1184                         sample_sum += hc->samples [j];
1185                         thread_sum += hc->thread_counts [j];
1186                 }
1187
1188                 average_throughput = sample_sum / sample_count;
1189                 average_thread_count = thread_sum / sample_count;
1190
1191                 if (average_throughput > 0 && average_thread_count > 0) {
1192                         gdouble noise_for_confidence, adjacent_period_1, adjacent_period_2;
1193
1194                         /* Calculate the periods of the adjacent frequency bands we'll be using to
1195                          * measure noise levels. We want the two adjacent Fourier frequency bands. */
1196                         adjacent_period_1 = sample_count / (((gdouble) sample_count) / ((gdouble) hc->wave_period) + 1);
1197                         adjacent_period_2 = sample_count / (((gdouble) sample_count) / ((gdouble) hc->wave_period) - 1);
1198
1199                         /* Get the the three different frequency components of the throughput (scaled by average
1200                          * throughput). Our "error" estimate (the amount of noise that might be present in the
1201                          * frequency band we're really interested in) is the average of the adjacent bands. */
1202                         throughput_wave_component = mono_double_complex_scalar_div (hill_climbing_get_wave_component (hc->samples, sample_count, hc->wave_period), average_throughput);
1203                         throughput_error_estimate = cabs (mono_double_complex_scalar_div (hill_climbing_get_wave_component (hc->samples, sample_count, adjacent_period_1), average_throughput));
1204
1205                         if (adjacent_period_2 <= sample_count) {
1206                                 throughput_error_estimate = MAX (throughput_error_estimate, cabs (mono_double_complex_scalar_div (hill_climbing_get_wave_component (
1207                                         hc->samples, sample_count, adjacent_period_2), average_throughput)));
1208                         }
1209
1210                         /* Do the same for the thread counts, so we have something to compare to. We don't
1211                          * measure thread count noise, because there is none; these are exact measurements. */
1212                         thread_wave_component = mono_double_complex_scalar_div (hill_climbing_get_wave_component (hc->thread_counts, sample_count, hc->wave_period), average_thread_count);
1213
1214                         /* Update our moving average of the throughput noise. We'll use this
1215                          * later as feedback to determine the new size of the thread wave. */
1216                         if (hc->average_throughput_noise == 0) {
1217                                 hc->average_throughput_noise = throughput_error_estimate;
1218                         } else {
1219                                 hc->average_throughput_noise = (hc->throughput_error_smoothing_factor * throughput_error_estimate)
1220                                         + ((1.0 + hc->throughput_error_smoothing_factor) * hc->average_throughput_noise);
1221                         }
1222
1223                         if (cabs (thread_wave_component) > 0) {
1224                                 /* Adjust the throughput wave so it's centered around the target wave,
1225                                  * and then calculate the adjusted throughput/thread ratio. */
1226                                 ratio = mono_double_complex_div (mono_double_complex_sub (throughput_wave_component, mono_double_complex_scalar_mul(thread_wave_component, hc->target_throughput_ratio)), thread_wave_component);
1227                                 transition = TRANSITION_CLIMBING_MOVE;
1228                         } else {
1229                                 ratio = mono_double_complex_make (0, 0);
1230                                 transition = TRANSITION_STABILIZING;
1231                         }
1232
1233                         noise_for_confidence = MAX (hc->average_throughput_noise, throughput_error_estimate);
1234                         if (noise_for_confidence > 0) {
1235                                 confidence = cabs (thread_wave_component) / noise_for_confidence / hc->target_signal_to_noise_ratio;
1236                         } else {
1237                                 /* there is no noise! */
1238                                 confidence = 1.0;
1239                         }
1240                 }
1241         }
1242
1243         /* We use just the real part of the complex ratio we just calculated. If the throughput signal
1244          * is exactly in phase with the thread signal, this will be the same as taking the magnitude of
1245          * the complex move and moving that far up. If they're 180 degrees out of phase, we'll move
1246          * backward (because this indicates that our changes are having the opposite of the intended effect).
1247          * If they're 90 degrees out of phase, we won't move at all, because we can't tell wether we're
1248          * having a negative or positive effect on throughput. */
1249         move = creal (ratio);
1250         move = CLAMP (move, -1.0, 1.0);
1251
1252         /* Apply our confidence multiplier. */
1253         move *= CLAMP (confidence, -1.0, 1.0);
1254
1255         /* Now apply non-linear gain, such that values around zero are attenuated, while higher values
1256          * are enhanced. This allows us to move quickly if we're far away from the target, but more slowly
1257         * if we're getting close, giving us rapid ramp-up without wild oscillations around the target. */
1258         gain = hc->max_change_per_second * sample_duration;
1259         move = pow (fabs (move), hc->gain_exponent) * (move >= 0.0 ? 1 : -1) * gain;
1260         move = MIN (move, hc->max_change_per_sample);
1261
1262         /* If the result was positive, and CPU is > 95%, refuse the move. */
1263         if (move > 0.0 && threadpool->cpu_usage > CPU_USAGE_HIGH)
1264                 move = 0.0;
1265
1266         /* Apply the move to our control setting. */
1267         hc->current_control_setting += move;
1268
1269         /* Calculate the new thread wave magnitude, which is based on the moving average we've been keeping of the
1270          * throughput error.  This average starts at zero, so we'll start with a nice safe little wave at first. */
1271         new_thread_wave_magnitude = (gint)(0.5 + (hc->current_control_setting * hc->average_throughput_noise
1272                 * hc->target_signal_to_noise_ratio * hc->thread_magnitude_multiplier * 2.0));
1273         new_thread_wave_magnitude = CLAMP (new_thread_wave_magnitude, 1, hc->max_thread_wave_magnitude);
1274
1275         /* Make sure our control setting is within the ThreadPool's limits. */
1276         hc->current_control_setting = CLAMP (hc->current_control_setting, threadpool->limit_worker_min, threadpool->limit_worker_max - new_thread_wave_magnitude);
1277
1278         /* Calculate the new thread count (control setting + square wave). */
1279         new_thread_count = (gint)(hc->current_control_setting + new_thread_wave_magnitude * ((hc->total_samples / (hc->wave_period / 2)) % 2));
1280
1281         /* Make sure the new thread count doesn't exceed the ThreadPool's limits. */
1282         new_thread_count = CLAMP (new_thread_count, threadpool->limit_worker_min, threadpool->limit_worker_max);
1283
1284         if (new_thread_count != current_thread_count)
1285                 hill_climbing_change_thread_count (new_thread_count, transition);
1286
1287         if (creal (ratio) < 0.0 && new_thread_count == threadpool->limit_worker_min)
1288                 *adjustment_interval = (gint)(0.5 + hc->current_sample_interval * (10.0 * MAX (-1.0 * creal (ratio), 1.0)));
1289         else
1290                 *adjustment_interval = hc->current_sample_interval;
1291
1292         return new_thread_count;
1293 }
1294
1295 static void
1296 heuristic_notify_work_completed (void)
1297 {
1298         g_assert (threadpool);
1299
1300         InterlockedIncrement (&threadpool->heuristic_completions);
1301         threadpool->heuristic_last_dequeue = mono_msec_ticks ();
1302 }
1303
1304 static gboolean
1305 heuristic_should_adjust (void)
1306 {
1307         g_assert (threadpool);
1308
1309         if (threadpool->heuristic_last_dequeue > threadpool->heuristic_last_adjustment + threadpool->heuristic_adjustment_interval) {
1310                 ThreadPoolCounter counter;
1311                 counter.as_gint64 = COUNTER_READ();
1312                 if (counter._.working <= counter._.max_working)
1313                         return TRUE;
1314         }
1315
1316         return FALSE;
1317 }
1318
1319 static void
1320 heuristic_adjust (void)
1321 {
1322         g_assert (threadpool);
1323
1324         if (mono_coop_mutex_trylock (&threadpool->heuristic_lock) == 0) {
1325                 gint32 completions = InterlockedExchange (&threadpool->heuristic_completions, 0);
1326                 gint64 sample_end = mono_msec_ticks ();
1327                 gint64 sample_duration = sample_end - threadpool->heuristic_sample_start;
1328
1329                 if (sample_duration >= threadpool->heuristic_adjustment_interval / 2) {
1330                         ThreadPoolCounter counter;
1331                         gint16 new_thread_count;
1332
1333                         counter.as_gint64 = COUNTER_READ ();
1334                         new_thread_count = hill_climbing_update (counter._.max_working, sample_duration, completions, &threadpool->heuristic_adjustment_interval);
1335
1336                         COUNTER_ATOMIC (counter, { counter._.max_working = new_thread_count; });
1337
1338                         if (new_thread_count > counter._.max_working)
1339                                 worker_request (mono_domain_get ());
1340
1341                         threadpool->heuristic_sample_start = sample_end;
1342                         threadpool->heuristic_last_adjustment = mono_msec_ticks ();
1343                 }
1344
1345                 mono_coop_mutex_unlock (&threadpool->heuristic_lock);
1346         }
1347 }
1348
1349 void
1350 mono_threadpool_ms_cleanup (void)
1351 {
1352         #ifndef DISABLE_SOCKETS
1353                 mono_threadpool_ms_io_cleanup ();
1354         #endif
1355         mono_lazy_cleanup (&status, cleanup);
1356 }
1357
1358 MonoAsyncResult *
1359 mono_threadpool_ms_begin_invoke (MonoDomain *domain, MonoObject *target, MonoMethod *method, gpointer *params, MonoError *error)
1360 {
1361         static MonoClass *async_call_klass = NULL;
1362         MonoMethodMessage *message;
1363         MonoAsyncResult *async_result;
1364         MonoAsyncCall *async_call;
1365         MonoDelegate *async_callback = NULL;
1366         MonoObject *state = NULL;
1367
1368         if (!async_call_klass)
1369                 async_call_klass = mono_class_load_from_name (mono_defaults.corlib, "System", "MonoAsyncCall");
1370
1371         mono_lazy_initialize (&status, initialize);
1372
1373         mono_error_init (error);
1374
1375         message = mono_method_call_message_new (method, params, mono_get_delegate_invoke (method->klass), (params != NULL) ? (&async_callback) : NULL, (params != NULL) ? (&state) : NULL, error);
1376         return_val_if_nok (error, NULL);
1377
1378         async_call = (MonoAsyncCall*) mono_object_new_checked (domain, async_call_klass, error);
1379         return_val_if_nok (error, NULL);
1380
1381         MONO_OBJECT_SETREF (async_call, msg, message);
1382         MONO_OBJECT_SETREF (async_call, state, state);
1383
1384         if (async_callback) {
1385                 MONO_OBJECT_SETREF (async_call, cb_method, mono_get_delegate_invoke (((MonoObject*) async_callback)->vtable->klass));
1386                 MONO_OBJECT_SETREF (async_call, cb_target, async_callback);
1387         }
1388
1389         async_result = mono_async_result_new (domain, NULL, async_call->state, NULL, (MonoObject*) async_call, error);
1390         return_val_if_nok (error, NULL);
1391         MONO_OBJECT_SETREF (async_result, async_delegate, target);
1392
1393         mono_threadpool_ms_enqueue_work_item (domain, (MonoObject*) async_result, error);
1394         return_val_if_nok (error, NULL);
1395
1396         return async_result;
1397 }
1398
1399 MonoObject *
1400 mono_threadpool_ms_end_invoke (MonoAsyncResult *ares, MonoArray **out_args, MonoObject **exc, MonoError *error)
1401 {
1402         MonoAsyncCall *ac;
1403
1404         mono_error_init (error);
1405         g_assert (exc);
1406         g_assert (out_args);
1407
1408         *exc = NULL;
1409         *out_args = NULL;
1410
1411         /* check if already finished */
1412         mono_monitor_enter ((MonoObject*) ares);
1413
1414         if (ares->endinvoke_called) {
1415                 mono_error_set_invalid_operation(error, "Delegate EndInvoke method called more than once");
1416                 mono_monitor_exit ((MonoObject*) ares);
1417                 return NULL;
1418         }
1419
1420         ares->endinvoke_called = 1;
1421
1422         /* wait until we are really finished */
1423         if (ares->completed) {
1424                 mono_monitor_exit ((MonoObject *) ares);
1425         } else {
1426                 gpointer wait_event;
1427                 if (ares->handle) {
1428                         wait_event = mono_wait_handle_get_handle ((MonoWaitHandle*) ares->handle);
1429                 } else {
1430                         wait_event = mono_w32event_create (TRUE, FALSE);
1431                         g_assert(wait_event);
1432                         MonoWaitHandle *wait_handle = mono_wait_handle_new (mono_object_domain (ares), wait_event, error);
1433                         if (!is_ok (error)) {
1434                                 CloseHandle (wait_event);
1435                                 return NULL;
1436                         }
1437                         MONO_OBJECT_SETREF (ares, handle, (MonoObject*) wait_handle);
1438                 }
1439                 mono_monitor_exit ((MonoObject*) ares);
1440                 MONO_ENTER_GC_SAFE;
1441                 WaitForSingleObjectEx (wait_event, INFINITE, TRUE);
1442                 MONO_EXIT_GC_SAFE;
1443         }
1444
1445         ac = (MonoAsyncCall*) ares->object_data;
1446         g_assert (ac);
1447
1448         *exc = ac->msg->exc; /* FIXME: GC add write barrier */
1449         *out_args = ac->out_args;
1450         return ac->res;
1451 }
1452
1453 gboolean
1454 mono_threadpool_ms_remove_domain_jobs (MonoDomain *domain, int timeout)
1455 {
1456         gint res;
1457         gint64 now, end;
1458         ThreadPoolDomain *tpdomain;
1459         ThreadPoolDomainCleanupSemaphore *cleanup_semaphore;
1460
1461         g_assert (domain);
1462         g_assert (timeout >= -1);
1463
1464         g_assert (mono_domain_is_unloading (domain));
1465
1466         if (timeout != -1)
1467                 end = mono_msec_ticks () + timeout;
1468
1469 #ifndef DISABLE_SOCKETS
1470         mono_threadpool_ms_io_remove_domain_jobs (domain);
1471         if (timeout != -1) {
1472                 if (mono_msec_ticks () > end)
1473                         return FALSE;
1474         }
1475 #endif
1476
1477         /*
1478         * There might be some threads out that could be about to execute stuff from the given domain.
1479         * We avoid that by waiting on a semaphore to be pulsed by the thread that reaches zero.
1480         * The semaphore is only created for domains which queued threadpool jobs.
1481         * We always wait on the semaphore rather than ensuring domain->threadpool_jobs is 0.
1482         * There may be pending outstanding requests which will create new jobs.
1483         * The semaphore is signaled the threadpool domain has been removed from list
1484         * and we know no more jobs for the domain will be processed.
1485         */
1486
1487         mono_lazy_initialize(&status, initialize);
1488         mono_coop_mutex_lock(&threadpool->domains_lock);
1489
1490         tpdomain = domain_get (domain, FALSE);
1491         if (!tpdomain || tpdomain->outstanding_request == 0) {
1492                 mono_coop_mutex_unlock(&threadpool->domains_lock);
1493                 return TRUE;
1494         }
1495
1496         mono_coop_mutex_unlock(&threadpool->domains_lock);
1497
1498         g_assert (domain->cleanup_semaphore);
1499
1500         cleanup_semaphore = (ThreadPoolDomainCleanupSemaphore*) domain->cleanup_semaphore;
1501
1502         if (timeout == -1) {
1503                 res = mono_coop_sem_wait (&cleanup_semaphore->sem, MONO_SEM_FLAGS_NONE);
1504                 g_assert (res == MONO_SEM_TIMEDWAIT_RET_SUCCESS);
1505         } else {
1506                 now = mono_msec_ticks();
1507                 if (now > end)
1508                         return FALSE;
1509                 res = mono_coop_sem_timedwait (&cleanup_semaphore->sem, end - now, MONO_SEM_FLAGS_NONE);
1510         }
1511
1512         if (InterlockedDecrement (&cleanup_semaphore->ref) == 0) {
1513                 mono_coop_sem_destroy (&cleanup_semaphore->sem);
1514                 g_free (cleanup_semaphore);
1515                 domain->cleanup_semaphore = NULL;
1516         }
1517
1518         return res == MONO_SEM_TIMEDWAIT_RET_SUCCESS;
1519 }
1520
1521 void
1522 mono_threadpool_ms_suspend (void)
1523 {
1524         if (threadpool)
1525                 threadpool->suspended = TRUE;
1526 }
1527
1528 void
1529 mono_threadpool_ms_resume (void)
1530 {
1531         if (threadpool)
1532                 threadpool->suspended = FALSE;
1533 }
1534
1535 void
1536 ves_icall_System_Threading_ThreadPool_GetAvailableThreadsNative (gint32 *worker_threads, gint32 *completion_port_threads)
1537 {
1538         ThreadPoolCounter counter;
1539
1540         if (!worker_threads || !completion_port_threads)
1541                 return;
1542
1543         mono_lazy_initialize (&status, initialize);
1544
1545         counter.as_gint64 = COUNTER_READ ();
1546
1547         *worker_threads = MAX (0, threadpool->limit_worker_max - counter._.active);
1548         *completion_port_threads = threadpool->limit_io_max;
1549 }
1550
1551 void
1552 ves_icall_System_Threading_ThreadPool_GetMinThreadsNative (gint32 *worker_threads, gint32 *completion_port_threads)
1553 {
1554         if (!worker_threads || !completion_port_threads)
1555                 return;
1556
1557         mono_lazy_initialize (&status, initialize);
1558
1559         *worker_threads = threadpool->limit_worker_min;
1560         *completion_port_threads = threadpool->limit_io_min;
1561 }
1562
1563 void
1564 ves_icall_System_Threading_ThreadPool_GetMaxThreadsNative (gint32 *worker_threads, gint32 *completion_port_threads)
1565 {
1566         if (!worker_threads || !completion_port_threads)
1567                 return;
1568
1569         mono_lazy_initialize (&status, initialize);
1570
1571         *worker_threads = threadpool->limit_worker_max;
1572         *completion_port_threads = threadpool->limit_io_max;
1573 }
1574
1575 MonoBoolean
1576 ves_icall_System_Threading_ThreadPool_SetMinThreadsNative (gint32 worker_threads, gint32 completion_port_threads)
1577 {
1578         mono_lazy_initialize (&status, initialize);
1579
1580         if (worker_threads <= 0 || worker_threads > threadpool->limit_worker_max)
1581                 return FALSE;
1582         if (completion_port_threads <= 0 || completion_port_threads > threadpool->limit_io_max)
1583                 return FALSE;
1584
1585         threadpool->limit_worker_min = worker_threads;
1586         threadpool->limit_io_min = completion_port_threads;
1587
1588         return TRUE;
1589 }
1590
1591 MonoBoolean
1592 ves_icall_System_Threading_ThreadPool_SetMaxThreadsNative (gint32 worker_threads, gint32 completion_port_threads)
1593 {
1594         gint cpu_count = mono_cpu_count ();
1595
1596         mono_lazy_initialize (&status, initialize);
1597
1598         if (worker_threads < threadpool->limit_worker_min || worker_threads < cpu_count)
1599                 return FALSE;
1600         if (completion_port_threads < threadpool->limit_io_min || completion_port_threads < cpu_count)
1601                 return FALSE;
1602
1603         threadpool->limit_worker_max = worker_threads;
1604         threadpool->limit_io_max = completion_port_threads;
1605
1606         return TRUE;
1607 }
1608
1609 void
1610 ves_icall_System_Threading_ThreadPool_InitializeVMTp (MonoBoolean *enable_worker_tracking)
1611 {
1612         if (enable_worker_tracking) {
1613                 // TODO implement some kind of switch to have the possibily to use it
1614                 *enable_worker_tracking = FALSE;
1615         }
1616
1617         mono_lazy_initialize (&status, initialize);
1618 }
1619
1620 MonoBoolean
1621 ves_icall_System_Threading_ThreadPool_NotifyWorkItemComplete (void)
1622 {
1623         ThreadPoolCounter counter;
1624
1625         if (mono_domain_is_unloading (mono_domain_get ()) || mono_runtime_is_shutting_down ())
1626                 return FALSE;
1627
1628         heuristic_notify_work_completed ();
1629
1630         if (heuristic_should_adjust ())
1631                 heuristic_adjust ();
1632
1633         counter.as_gint64 = COUNTER_READ ();
1634         return counter._.working <= counter._.max_working;
1635 }
1636
1637 void
1638 ves_icall_System_Threading_ThreadPool_NotifyWorkItemProgressNative (void)
1639 {
1640         heuristic_notify_work_completed ();
1641
1642         if (heuristic_should_adjust ())
1643                 heuristic_adjust ();
1644 }
1645
1646 void
1647 ves_icall_System_Threading_ThreadPool_ReportThreadStatus (MonoBoolean is_working)
1648 {
1649         // TODO
1650         MonoError error;
1651         mono_error_set_not_implemented (&error, "");
1652         mono_error_set_pending_exception (&error);
1653 }
1654
1655 MonoBoolean
1656 ves_icall_System_Threading_ThreadPool_RequestWorkerThread (void)
1657 {
1658         return worker_request (mono_domain_get ());
1659 }
1660
1661 MonoBoolean G_GNUC_UNUSED
1662 ves_icall_System_Threading_ThreadPool_PostQueuedCompletionStatus (MonoNativeOverlapped *native_overlapped)
1663 {
1664         /* This copy the behavior of the current Mono implementation */
1665         MonoError error;
1666         mono_error_set_not_implemented (&error, "");
1667         mono_error_set_pending_exception (&error);
1668         return FALSE;
1669 }
1670
1671 MonoBoolean G_GNUC_UNUSED
1672 ves_icall_System_Threading_ThreadPool_BindIOCompletionCallbackNative (gpointer file_handle)
1673 {
1674         /* This copy the behavior of the current Mono implementation */
1675         return TRUE;
1676 }
1677
1678 MonoBoolean G_GNUC_UNUSED
1679 ves_icall_System_Threading_ThreadPool_IsThreadPoolHosted (void)
1680 {
1681         return FALSE;
1682 }