Start sampler for the runtime profiler even when we can't setup a signal handler.

src/platform-linux.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 566 matching lines @@
 
 Thread::~Thread() {
 }
 
 
 static void* ThreadEntry(void* arg) {
   Thread* thread = reinterpret_cast<Thread*>(arg);
   // This is also initialized by the first argument to pthread_create() but we
   // don't know which thread will run first (the original thread or the new
   // one) so we initialize it here too.
-  prctl(PR_SET_NAME, reinterpret_cast<unsigned long>(thread->name()), 0, 0, 0);
+  prctl(PR_SET_NAME,
+        reinterpret_cast<unsigned long>(thread->name()),  // NOLINT
+        0, 0, 0);
   thread->thread_handle_data()->thread_ = pthread_self();
   ASSERT(thread->IsValid());
   thread->Run();
   return NULL;
 }
 
 
 void Thread::set_name(const char* name) {
   strncpy(name_, name, sizeof(name_));
   name_[sizeof(name_) - 1] = '\0';
@@ skipping 266 matching lines @@
         Sleep(HALF_INTERVAL);
       } else {
         if (sampler_->IsProfiling()) SendProfilingSignal();
         if (RuntimeProfiler::IsEnabled()) RuntimeProfiler::NotifyTick();
         Sleep(FULL_INTERVAL);
       }
     }
   }
 
   void SendProfilingSignal() {
+    if (!signal_handler_installed_) return;
     // Glibc doesn't provide a wrapper for tgkill(2).
     syscall(SYS_tgkill, vm_tgid_, vm_tid_, SIGPROF);
   }
 
   void Sleep(SleepInterval full_or_half) {
     // Convert ms to us and subtract 100 us to compensate delays
     // occuring during signal delivery.
     useconds_t interval = sampler_->interval_ * 1000 - 100;
     if (full_or_half == HALF_INTERVAL) interval /= 2;
     int result = usleep(interval);
@@ skipping 46 matching lines @@
   // There can only be one active sampler at the time on POSIX
   // platforms.
   ASSERT(!IsActive());
   vm_tid_ = GetThreadID();
 
   // Request profiling signals.
   struct sigaction sa;
   sa.sa_sigaction = ProfilerSignalHandler;
   sigemptyset(&sa.sa_mask);
   sa.sa_flags = SA_RESTART | SA_SIGINFO;
-  if (sigaction(SIGPROF, &sa, &data_->old_signal_handler_) != 0) return;
-  data_->signal_handler_installed_ = true;
+  data_->signal_handler_installed_ =
+      sigaction(SIGPROF, &sa, &data_->old_signal_handler_) == 0;
 
   // Start a thread that sends SIGPROF signal to VM thread.
   // Sending the signal ourselves instead of relying on itimer provides
   // much better accuracy.
   SetActive(true);
   if (pthread_create(
           &data_->signal_sender_thread_, NULL, SenderEntry, data_) == 0) {
     data_->signal_sender_launched_ = true;
   }
 
@@ skipping 20 matching lines @@
   }
 
   // This sampler is no longer the active sampler.
   active_sampler_ = NULL;
 }
 
 
 #endif  // ENABLE_LOGGING_AND_PROFILING
 
 } }  // namespace v8::internal