Merge pull request #2810 from kumpera/fix_hazard_free

[mono.git] / mono / metadata / gc.c

diff --git a/mono/metadata/gc.c b/mono/metadata/gc.c
index 172660d1b55e93efbf291e6612ab9877883782ff..148bbedee6444a74666934c4a37d4b5377e69b2e 100644 (file)
--- a/mono/metadata/gc.c
+++ b/mono/metadata/gc.c
@@ -40,6 +40,7 @@
 #include <mono/utils/mono-threads.h>
 #include <mono/utils/atomic.h>
 #include <mono/utils/mono-coop-semaphore.h>
+#include <mono/utils/hazard-pointer.h>
 
 #ifndef HOST_WIN32
 #include <pthread.h>
@@ -639,6 +640,41 @@ mono_gc_finalize_notify (void)
        mono_coop_sem_post (&finalizer_sem);
 }
 
+/*
+This is the number of entries allowed in the hazard free queue before
+we explicitly cycle the finalizer thread to trigger pumping the queue.
+
+It was picked empirically by running the corlib test suite in a stress
+scenario where all hazard entries are queued.
+
+In this extreme scenario we double the number of times we cycle the finalizer
+thread compared to just GC calls.
+
+Entries are usually in the order of 100's of bytes each, so we're limiting
+floating garbage to be in the order of a dozen kb.
+*/
+static gboolean finalizer_thread_pulsed;
+#define HAZARD_QUEUE_OVERFLOW_SIZE 20
+
+static void
+hazard_free_queue_is_too_big (size_t size)
+{
+       if (size < HAZARD_QUEUE_OVERFLOW_SIZE)
+               return;
+
+       if (finalizer_thread_pulsed || InterlockedCompareExchange (&finalizer_thread_pulsed, TRUE, FALSE))
+               return;
+
+       mono_gc_finalize_notify ();
+}
+
+static void
+hazard_free_queue_pump (void)
+{
+       mono_thread_hazardous_try_free_all ();
+       finalizer_thread_pulsed = FALSE;
+}
+
 #ifdef HAVE_BOEHM_GC
 
 static void
@@ -714,6 +750,9 @@ finalizer_thread (gpointer unused)
 {
        gboolean wait = TRUE;
 
+       /* Register a hazard free queue pump callback */
+       mono_hazard_pointer_install_free_queue_size_callback (hazard_free_queue_is_too_big);
+
        while (!finished) {
                /* Wait to be notified that there's at least one
                 * finaliser to run
@@ -758,6 +797,8 @@ finalizer_thread (gpointer unused)
 
                reference_queue_proccess_all ();
 
+               hazard_free_queue_pump ();
+
                /* Avoid posting the pending done event until there are pending finalizers */
                if (mono_coop_sem_timedwait (&finalizer_sem, 0, MONO_SEM_FLAGS_NONE) == 0) {
                        /* Don't wait again at the start of the loop */