In ProfilerSignalHandler ensure that thread we are trying to sample locked the isolate.

src/platform-freebsd.cc

 // Copyright 2006-2008 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 624 matching lines @@
 
 
 static void ProfilerSignalHandler(int signal, siginfo_t* info, void* context) {
   USE(info);
   if (signal != SIGPROF) return;
   Isolate* isolate = Isolate::UncheckedCurrent();
   if (isolate == NULL || !isolate->IsInitialized() || !isolate->IsInUse()) {
     // We require a fully initialized and entered isolate.
     return;
   }
+  if (v8::Locker::IsActive() &&
+      !isolate->thread_manager()->IsLockedByCurrentThread()) {
+    return;
+  }
+
   Sampler* sampler = isolate->logger()->sampler();
   if (sampler == NULL || !sampler->IsActive()) return;
 
   TickSample sample_obj;
   TickSample* sample = CpuProfiler::TickSampleEvent(isolate);
   if (sample == NULL) sample = &sample_obj;
 
   // Extracting the sample from the context is extremely machine dependent.
   ucontext_t* ucontext = reinterpret_cast<ucontext_t*>(context);
   mcontext_t& mcontext = ucontext->uc_mcontext;
@@ skipping 181 matching lines @@
 
 void Sampler::Stop() {
   ASSERT(IsActive());
   SignalSender::RemoveActiveSampler(this);
   SetActive(false);
 }
 
 #endif  // ENABLE_LOGGING_AND_PROFILING
 
 } }  // namespace v8::internal