Attempt to collect more garbage before panicking with out of memory.

src/heap.cc

 // Copyright 2010 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 411 matching lines @@
 void Heap::CollectAllGarbage(bool force_compaction) {
   // Since we are ignoring the return value, the exact choice of space does
   // not matter, so long as we do not specify NEW_SPACE, which would not
   // cause a full GC.
   MarkCompactCollector::SetForceCompaction(force_compaction);
   CollectGarbage(OLD_POINTER_SPACE);
   MarkCompactCollector::SetForceCompaction(false);
 }
 
 
-void Heap::CollectGarbage(AllocationSpace space) {
+void Heap::CollectAllAvailableGarbage() {
+  // Since we are ignoring the return value, the exact choice of space does
+  // not matter, so long as we do not specify NEW_SPACE, which would not
+  // cause a full GC.
+  MarkCompactCollector::SetForceCompaction(true);
+
+  // Major GC would invoke weak handle callbacks on weakly reachable
+  // handles, but won't collect weakly reachable objects until next
+  // major GC.  Therefore if we collect aggressively and weak handle callback
+  // has been invoked, we rerun major GC to release objects which become
+  // garbage.
+  // Note: as weak callbacks can execute arbitrary code, we cannot
+  // hope that eventually there will be no weak callbacks invocations.
+  // Therefore stop recollecting after several attempts.
+  const int kMaxNumberOfAttempts = 7;
+  for (int attempt = 0; attempt < kMaxNumberOfAttempts; attempt++) {
+    if (!CollectGarbage(OLD_POINTER_SPACE, MARK_COMPACTOR)) {
+      break;
+    }
+  }
+  MarkCompactCollector::SetForceCompaction(false);
+}
+
+
+bool Heap::CollectGarbage(AllocationSpace space, GarbageCollector collector) {
   // The VM is in the GC state until exiting this function.
   VMState state(GC);
 
 #ifdef DEBUG
   // Reset the allocation timeout to the GC interval, but make sure to
   // allow at least a few allocations after a collection. The reason
   // for this is that we have a lot of allocation sequences and we
   // assume that a garbage collection will allow the subsequent
   // allocation attempts to go through.
   allocation_timeout_ = Max(6, FLAG_gc_interval);
 #endif
 
+  bool next_gc_likely_to_collect_more = false;
+
   { GCTracer tracer;
     GarbageCollectionPrologue();
     // The GC count was incremented in the prologue.  Tell the tracer about
     // it.
     tracer.set_gc_count(gc_count_);
 
-    GarbageCollector collector = SelectGarbageCollector(space);
     // Tell the tracer which collector we've selected.
     tracer.set_collector(collector);
 
     HistogramTimer* rate = (collector == SCAVENGER)
         ? &Counters::gc_scavenger
         : &Counters::gc_compactor;
     rate->Start();
-    PerformGarbageCollection(collector, &tracer);
+    next_gc_likely_to_collect_more =
+        PerformGarbageCollection(collector, &tracer);
     rate->Stop();
 
     GarbageCollectionEpilogue();
   }
 
 
 #ifdef ENABLE_LOGGING_AND_PROFILING
   if (FLAG_log_gc) HeapProfiler::WriteSample();
   if (CpuProfiler::is_profiling()) CpuProfiler::ProcessMovedFunctions();
 #endif
+
+  return next_gc_likely_to_collect_more;
 }
 
 
 void Heap::PerformScavenge() {
   GCTracer tracer;
   PerformGarbageCollection(SCAVENGER, &tracer);
 }
 
 
 #ifdef DEBUG
@@ skipping 166 matching lines @@
     set_survival_rate_trend(DECREASING);
   } else if (survival_rate_diff < -kYoungSurvivalRateAllowedDeviation) {
     set_survival_rate_trend(INCREASING);
   } else {
     set_survival_rate_trend(STABLE);
   }
 
   survival_rate_ = survival_rate;
 }
 
-void Heap::PerformGarbageCollection(GarbageCollector collector,
+bool Heap::PerformGarbageCollection(GarbageCollector collector,
                                     GCTracer* tracer) {
+  bool next_gc_likely_to_collect_more = false;
+
   if (collector != SCAVENGER) {
     PROFILE(CodeMovingGCEvent());
   }
 
   VerifySymbolTable();
   if (collector == MARK_COMPACTOR && global_gc_prologue_callback_) {
     ASSERT(!allocation_allowed_);
     GCTracer::Scope scope(tracer, GCTracer::Scope::EXTERNAL);
     global_gc_prologue_callback_();
   }
@@ skipping 45 matching lines @@
     tracer_ = NULL;
 
     UpdateSurvivalRateTrend(start_new_space_size);
   }
 
   Counters::objs_since_last_young.Set(0);
 
   if (collector == MARK_COMPACTOR) {
     DisableAssertNoAllocation allow_allocation;
     GCTracer::Scope scope(tracer, GCTracer::Scope::EXTERNAL);
-    GlobalHandles::PostGarbageCollectionProcessing();
+    next_gc_likely_to_collect_more =
+        GlobalHandles::PostGarbageCollectionProcessing();
   }
 
   // Update relocatables.
   Relocatable::PostGarbageCollectionProcessing();
 
   if (collector == MARK_COMPACTOR) {
     // Register the amount of external allocated memory.
     amount_of_external_allocated_memory_at_last_global_gc_ =
         amount_of_external_allocated_memory_;
   }
 
   GCCallbackFlags callback_flags = tracer->is_compacting()
       ? kGCCallbackFlagCompacted
       : kNoGCCallbackFlags;
   for (int i = 0; i < gc_epilogue_callbacks_.length(); ++i) {
     if (gc_type & gc_epilogue_callbacks_[i].gc_type) {
       gc_epilogue_callbacks_[i].callback(gc_type, callback_flags);
     }
   }
 
   if (collector == MARK_COMPACTOR && global_gc_epilogue_callback_) {
     ASSERT(!allocation_allowed_);
     GCTracer::Scope scope(tracer, GCTracer::Scope::EXTERNAL);
     global_gc_epilogue_callback_();
   }
   VerifySymbolTable();
+
+  return next_gc_likely_to_collect_more;
 }
 
 
 void Heap::MarkCompact(GCTracer* tracer) {
   gc_state_ = MARK_COMPACT;
   LOG(ResourceEvent("markcompact", "begin"));
 
   MarkCompactCollector::Prepare(tracer);
 
   bool is_compacting = MarkCompactCollector::IsCompacting();
@@ skipping 4472 matching lines @@
 void ExternalStringTable::TearDown() {
   new_space_strings_.Free();
   old_space_strings_.Free();
 }
 
 
 List<Object*> ExternalStringTable::new_space_strings_;
 List<Object*> ExternalStringTable::old_space_strings_;
 
 } }  // namespace v8::internal