Sampling heap profiler: Force Full GC before retrieving the profile.

src/profiler/sampling-heap-profiler.cc

 // Copyright 2015 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/profiler/sampling-heap-profiler.h"
 
 #include <stdint.h>
 #include <memory>
 #include "src/api.h"
 #include "src/base/utils/random-number-generator.h"
@@ skipping 29 matching lines @@
 // sampled is 1-exp(-S/R). This function uses the above probability to
 // approximate the true number of allocations with size *size* given that
 // *count* samples were observed.
 v8::AllocationProfile::Allocation SamplingHeapProfiler::ScaleSample(
     size_t size, unsigned int count) {
   double scale = 1.0 / (1.0 - std::exp(-static_cast<double>(size) / rate_));
   // Round count instead of truncating.
   return {size, static_cast<unsigned int>(count * scale + 0.5)};
 }
 
-SamplingHeapProfiler::SamplingHeapProfiler(Heap* heap, StringsStorage* names,
-                                           uint64_t rate, int stack_depth)
+SamplingHeapProfiler::SamplingHeapProfiler(
+    Heap* heap, StringsStorage* names, uint64_t rate, int stack_depth,
+    v8::HeapProfiler::SamplingFlags flags)
     : isolate_(heap->isolate()),
       heap_(heap),
       new_space_observer_(new SamplingAllocationObserver(
           heap_, static_cast<intptr_t>(rate), rate, this,
           heap->isolate()->random_number_generator())),
       other_spaces_observer_(new SamplingAllocationObserver(
           heap_, static_cast<intptr_t>(rate), rate, this,
           heap->isolate()->random_number_generator())),
       names_(names),
       profile_root_(nullptr, "(root)", v8::UnboundScript::kNoScriptId, 0),
       samples_(),
       stack_depth_(stack_depth),
-      rate_(rate) {
+      rate_(rate),
+      flags_(flags) {
   CHECK_GT(rate_, 0);
   heap->new_space()->AddAllocationObserver(new_space_observer_.get());
   AllSpaces spaces(heap);
   for (Space* space = spaces.next(); space != nullptr; space = spaces.next()) {
     if (space != heap->new_space()) {
       space->AddAllocationObserver(other_spaces_observer_.get());
     }
   }
 }
 
@@ skipping 174 matching lines @@
   // not processed.
   for (size_t i = 0; i < child_len; i++) {
     current->children.push_back(
         TranslateAllocationNode(profile, node->children_[i], scripts));
   }
   node->pinned_ = false;
   return current;
 }
 
 v8::AllocationProfile* SamplingHeapProfiler::GetAllocationProfile() {
+  if (flags_ & v8::HeapProfiler::kSamplingForceGC) {
+    isolate_->heap()->CollectAllGarbage(Heap::kNoGCFlags,
+                                        "SamplingHeapProfiler");
+  }
   // To resolve positions to line/column numbers, we will need to look up
   // scripts. Build a map to allow fast mapping from script id to script.
   std::map<int, Handle<Script>> scripts;
   {
     Script::Iterator iterator(isolate_);
     while (Script* script = iterator.Next()) {
       scripts[script->id()] = handle(script);
     }
   }
   auto profile = new v8::internal::AllocationProfile();
   TranslateAllocationNode(profile, &profile_root_, scripts);
   return profile;
 }
 
 
 }  // namespace internal
 }  // namespace v8