Check if there is still time before finalizing an incremental collection.

src/heap/heap.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #include "src/accessors.h"
 #include "src/api.h"
 #include "src/base/bits.h"
 #include "src/base/once.h"
@@ skipping 4249 matching lines @@
   if (!IsHeapIterable()) {
     CollectAllGarbage(kMakeHeapIterableMask, "Heap::MakeHeapIterable");
   }
   if (mark_compact_collector()->sweeping_in_progress()) {
     mark_compact_collector()->EnsureSweepingCompleted();
   }
   DCHECK(IsHeapIterable());
 }
 
 
-void Heap::AdvanceIdleIncrementalMarking(intptr_t step_size) {
-  incremental_marking()->Step(step_size,
-                              IncrementalMarking::NO_GC_VIA_STACK_GUARD, true);
-
-  if (incremental_marking()->IsComplete()) {
+void Heap::TryFinalizeIdleIncrementalMarking(
+    size_t idle_time_in_ms, size_t size_of_objects,
+    size_t mark_compact_speed_in_bytes_per_ms) {
+  if (incremental_marking()->IsComplete() ||
+      (mark_compact_collector()->IsMarkingDequeEmpty() &&
+       gc_idle_time_handler_.ShouldDoMarkCompact(
+           idle_time_in_ms, size_of_objects,
+           mark_compact_speed_in_bytes_per_ms))) {
     bool uncommit = false;
     if (gc_count_at_last_idle_gc_ == gc_count_) {
       // No GC since the last full GC, the mutator is probably not active.
       isolate_->compilation_cache()->Clear();
       uncommit = true;
     }
     CollectAllGarbage(kReduceMemoryFootprintMask,
                       "idle notification: finalize incremental");
     gc_idle_time_handler_.NotifyIdleMarkCompact();
     gc_count_at_last_idle_gc_ = gc_count_;
@@ skipping 39 matching lines @@
   heap_state.used_new_space_size = new_space_.Size();
   heap_state.new_space_capacity = new_space_.Capacity();
   heap_state.new_space_allocation_throughput_in_bytes_per_ms =
       static_cast<size_t>(
           tracer()->NewSpaceAllocationThroughputInBytesPerMillisecond());
 
   GCIdleTimeAction action =
       gc_idle_time_handler_.Compute(idle_time_in_ms, heap_state);
 
   bool result = false;
+  int actual_time_in_ms = 0;
   switch (action.type) {
     case DONE:
       result = true;
       break;
-    case DO_INCREMENTAL_MARKING:
+    case DO_INCREMENTAL_MARKING: {
       if (incremental_marking()->IsStopped()) {
         incremental_marking()->Start();
       }
-      AdvanceIdleIncrementalMarking(action.parameter);
+      incremental_marking()->Step(action.parameter,
+                                  IncrementalMarking::NO_GC_VIA_STACK_GUARD,
+                                  IncrementalMarking::FORCE_MARKING,
+                                  IncrementalMarking::DO_NOT_FORCE_COMPLETION);
+      actual_time_in_ms = static_cast<int>(timer.Elapsed().InMilliseconds());
+      int remaining_idle_time_in_ms = idle_time_in_ms - actual_time_in_ms;
+      if (remaining_idle_time_in_ms > 0) {
+        TryFinalizeIdleIncrementalMarking(
+            remaining_idle_time_in_ms, heap_state.size_of_objects,
+            heap_state.mark_compact_speed_in_bytes_per_ms);
+      }
       break;
+    }
     case DO_FULL_GC: {
       HistogramTimerScope scope(isolate_->counters()->gc_context());
       const char* message = contexts_disposed_
                                 ? "idle notification: contexts disposed"
                                 : "idle notification: finalize idle round";
       CollectAllGarbage(kReduceMemoryFootprintMask, message);
       gc_idle_time_handler_.NotifyIdleMarkCompact();
       break;
     }
     case DO_SCAVENGE:
       CollectGarbage(NEW_SPACE, "idle notification: scavenge");
       break;
     case DO_FINALIZE_SWEEPING:
       mark_compact_collector()->EnsureSweepingCompleted();
       break;
     case DO_NOTHING:
       break;
   }
 
-  int actual_time_ms = static_cast<int>(timer.Elapsed().InMilliseconds());
-  if (actual_time_ms <= idle_time_in_ms) {
+  actual_time_in_ms = static_cast<int>(timer.Elapsed().InMilliseconds());
+  if (actual_time_in_ms <= idle_time_in_ms) {
     if (action.type != DONE && action.type != DO_NOTHING) {
       isolate()->counters()->gc_idle_time_limit_undershot()->AddSample(
-          idle_time_in_ms - actual_time_ms);
+          idle_time_in_ms - actual_time_in_ms);
     }
   } else {
     isolate()->counters()->gc_idle_time_limit_overshot()->AddSample(
-        actual_time_ms - idle_time_in_ms);
+        actual_time_in_ms - idle_time_in_ms);
   }
 
   if (FLAG_trace_idle_notification) {
     PrintF("Idle notification: requested idle time %d ms, actual time %d ms [",
-           idle_time_in_ms, actual_time_ms);
+           idle_time_in_ms, actual_time_in_ms);
     action.Print();
     PrintF("]\n");
   }
 
   contexts_disposed_ = 0;
   return result;
 }
 
 
 #ifdef DEBUG
@@ skipping 1766 matching lines @@
       static_cast<int>(object_sizes_last_time_[index]));
   CODE_AGE_LIST_COMPLETE(ADJUST_LAST_TIME_OBJECT_COUNT)
 #undef ADJUST_LAST_TIME_OBJECT_COUNT
 
   MemCopy(object_counts_last_time_, object_counts_, sizeof(object_counts_));
   MemCopy(object_sizes_last_time_, object_sizes_, sizeof(object_sizes_));
   ClearObjectStats();
 }
 }
 }  // namespace v8::internal