Do not record CPU profile samples when stack collection is failed.

src/profiler/sampler.cc

 // Copyright 2013 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/sampler.h"
 
 #if V8_OS_POSIX && !V8_OS_CYGWIN
 
 #define USE_SIGNALS
 
@@ skipping 653 matching lines @@
   state = isolate->current_vm_state();
   this->update_stats = update_stats;
 
   // Avoid collecting traces while doing GC.
   if (state == GC) return;
 
   Address js_entry_sp = isolate->js_entry_sp();
   if (js_entry_sp == 0) return;  // Not executing JS now.
 
   if (pc && IsNoFrameRegion(pc)) {
+    // Can't collect stack. Mark the sample as spoiled.
+    timestamp = base::TimeTicks();
     pc = 0;
     return;
   }
 
   ExternalCallbackScope* scope = isolate->external_callback_scope();
   Address handler = Isolate::handler(isolate->thread_local_top());
   // If there is a handler on top of the external callback scope then
   // we have already entrered JavaScript again and the external callback
   // is not the top function.
   if (scope && scope->scope_address() < handler) {
@@ skipping 10 matching lines @@
   }
 
   SafeStackFrameIterator it(isolate, reinterpret_cast<Address>(regs.fp),
                             reinterpret_cast<Address>(regs.sp), js_entry_sp);
   top_frame_type = it.top_frame_type();
 
   SampleInfo info;
   GetStackSample(isolate, regs, record_c_entry_frame,
                  reinterpret_cast<void**>(&stack[0]), kMaxFramesCount, &info);
   frames_count = static_cast<unsigned>(info.frames_count);
+  if (!frames_count) {
+    // It is executing JS but failed to collect a stack trace.
+    // Mark the sample as spoiled.
+    timestamp = base::TimeTicks();
+    pc = 0;
+  }
 }
 
 
 void TickSample::GetStackSample(Isolate* isolate, const v8::RegisterState& regs,
                                 RecordCEntryFrame record_c_entry_frame,
                                 void** frames, size_t frames_limit,
                                 v8::SampleInfo* sample_info) {
   sample_info->frames_count = 0;
   sample_info->vm_state = isolate->current_vm_state();
   if (sample_info->vm_state == GC) return;
@@ skipping 76 matching lines @@
 #endif
   base::NoBarrier_AtomicIncrement(&profiling_, -1);
 }
 
 
 void Sampler::SampleStack(const v8::RegisterState& state) {
   TickSample* sample = isolate_->cpu_profiler()->StartTickSample();
   TickSample sample_obj;
   if (sample == NULL) sample = &sample_obj;
   sample->Init(isolate_, state, TickSample::kIncludeCEntryFrame, true);
-  if (is_counting_samples_) {
+  if (is_counting_samples_ && !sample->timestamp.IsNull()) {
     if (sample->state == JS) ++js_sample_count_;
     if (sample->state == EXTERNAL) ++external_sample_count_;
   }
   Tick(sample);
   if (sample != &sample_obj) {
     isolate_->cpu_profiler()->FinishTickSample();
   }
 }
 
 
@@ skipping 40 matching lines @@
     SampleStack(state);
   }
   ResumeThread(profiled_thread);
 }
 
 #endif  // USE_SIGNALS
 
 
 }  // namespace internal
 }  // namespace v8