Merge up to 8597 to experimental/gc from the bleeding edge.

src/platform-linux.cc

Index: src/platform-linux.cc
===================================================================
--- src/platform-linux.cc	(revision 8618)
+++ src/platform-linux.cc	(working copy)
@@ -686,17 +686,15 @@
   pthread_t thread_;  // Thread handle for pthread.
 };
 
-Thread::Thread(Isolate* isolate, const Options& options)
+Thread::Thread(const Options& options)
     : data_(new PlatformData()),
-      isolate_(isolate),
       stack_size_(options.stack_size) {
   set_name(options.name);
 }
 
 
-Thread::Thread(Isolate* isolate, const char* name)
+Thread::Thread(const char* name)
     : data_(new PlatformData()),
-      isolate_(isolate),
       stack_size_(0) {
   set_name(name);
 }
@@ -717,7 +715,6 @@
         0, 0, 0);
   thread->data()->thread_ = pthread_self();
   ASSERT(thread->data()->thread_ != kNoThread);
-  Thread::SetThreadLocal(Isolate::isolate_key(), thread->isolate());
   thread->Run();
   return NULL;
 }
@@ -783,7 +780,6 @@
 
 class LinuxMutex : public Mutex {
  public:
-
   LinuxMutex() {
     pthread_mutexattr_t attrs;
     int result = pthread_mutexattr_init(&attrs);
@@ -1008,23 +1004,32 @@
   };
 
   explicit SignalSender(int interval)
-      : Thread(NULL, "SignalSender"),
+      : Thread("SignalSender"),
         vm_tgid_(getpid()),
         interval_(interval) {}
 
+  static void InstallSignalHandler() {
+    struct sigaction sa;
+    sa.sa_sigaction = ProfilerSignalHandler;
+    sigemptyset(&sa.sa_mask);
+    sa.sa_flags = SA_RESTART | SA_SIGINFO;
+    signal_handler_installed_ =
+        (sigaction(SIGPROF, &sa, &old_signal_handler_) == 0);
+  }
+
+  static void RestoreSignalHandler() {
+    if (signal_handler_installed_) {
+      sigaction(SIGPROF, &old_signal_handler_, 0);
+      signal_handler_installed_ = false;
+    }
+  }
+
   static void AddActiveSampler(Sampler* sampler) {
     ScopedLock lock(mutex_);
     SamplerRegistry::AddActiveSampler(sampler);
     if (instance_ == NULL) {
-      // Install a signal handler.
-      struct sigaction sa;
-      sa.sa_sigaction = ProfilerSignalHandler;
-      sigemptyset(&sa.sa_mask);
-      sa.sa_flags = SA_RESTART | SA_SIGINFO;
-      signal_handler_installed_ =
-          (sigaction(SIGPROF, &sa, &old_signal_handler_) == 0);
-
-      // Start a thread that sends SIGPROF signal to VM threads.
+      // Start a thread that will send SIGPROF signal to VM threads,
+      // when CPU profiling will be enabled.
       instance_ = new SignalSender(sampler->interval());
       instance_->Start();
     } else {
@@ -1036,16 +1041,10 @@
     ScopedLock lock(mutex_);
     SamplerRegistry::RemoveActiveSampler(sampler);
     if (SamplerRegistry::GetState() == SamplerRegistry::HAS_NO_SAMPLERS) {
-      RuntimeProfiler::WakeUpRuntimeProfilerThreadBeforeShutdown();
-      instance_->Join();
+      RuntimeProfiler::StopRuntimeProfilerThreadBeforeShutdown(instance_);
       delete instance_;
       instance_ = NULL;
-
-      // Restore the old signal handler.
-      if (signal_handler_installed_) {
-        sigaction(SIGPROF, &old_signal_handler_, 0);
-        signal_handler_installed_ = false;
-      }
+      RestoreSignalHandler();
     }
   }
 
@@ -1057,6 +1056,11 @@
       bool cpu_profiling_enabled =
           (state == SamplerRegistry::HAS_CPU_PROFILING_SAMPLERS);
       bool runtime_profiler_enabled = RuntimeProfiler::IsEnabled();
+      if (cpu_profiling_enabled && !signal_handler_installed_) {
+        InstallSignalHandler();
+      } else if (!cpu_profiling_enabled && signal_handler_installed_) {
+        RestoreSignalHandler();
+      }
       // When CPU profiling is enabled both JavaScript and C++ code is
       // profiled. We must not suspend.
       if (!cpu_profiling_enabled) {