Bug 970358 - Disable BackgroundHangMonitor on release builds. r=froydnj

toolkit/components/telemetry/Telemetry.cpp

@@ -2110,6 +2110,7 @@ TelemetryImpl::GetThreadHangStats(JSContext* cx, JS::MutableHandle<JS::Value> re
   }
   size_t threadIndex = 0;
 
+#ifdef MOZ_ENABLE_BACKGROUND_HANG_MONITOR
   /* First add active threads; we need to hold |iter| (and its lock)
      throughout this method to avoid a race condition where a thread can
      be recorded twice if the thread is destroyed while this method is
@@ -2123,6 +2124,7 @@ TelemetryImpl::GetThreadHangStats(JSContext* cx, JS::MutableHandle<JS::Value> re
       return NS_ERROR_FAILURE;
     }
   }
+#endif
 
   // Add saved threads next
   MutexAutoLock autoLock(mThreadHangStatsMutex);

xpcom/threads/BackgroundHangMonitor.cpp

@@ -410,6 +410,7 @@ BackgroundHangThread::NotifyActivity()
 BackgroundHangThread*
 BackgroundHangThread::FindThread()
 {
+#ifdef MOZ_ENABLE_BACKGROUND_HANG_MONITOR
   if (sTlsKey.initialized()) {
     // Use TLS if available
     return sTlsKey.get();
@@ -427,6 +428,7 @@ BackgroundHangThread::FindThread()
       return thread;
     }
   }
+#endif
   // Current thread is not initialized
   return nullptr;
 }
@@ -435,15 +437,18 @@ BackgroundHangThread::FindThread()
 void
 BackgroundHangMonitor::Startup()
 {
+#ifdef MOZ_ENABLE_BACKGROUND_HANG_MONITOR
   MOZ_ASSERT(!BackgroundHangManager::sInstance, "Already initialized");
   ThreadStackHelper::Startup();
   BackgroundHangThread::Startup();
   BackgroundHangManager::sInstance = new BackgroundHangManager();
+#endif
 }
 
 void
 BackgroundHangMonitor::Shutdown()
 {
+#ifdef MOZ_ENABLE_BACKGROUND_HANG_MONITOR
   MOZ_ASSERT(BackgroundHangManager::sInstance, "Not initialized");
   /* Scope our lock inside Shutdown() because the sInstance object can
      be destroyed as soon as we set sInstance to nullptr below, and
@@ -451,6 +456,7 @@ BackgroundHangMonitor::Shutdown()
   BackgroundHangManager::sInstance->Shutdown();
   BackgroundHangManager::sInstance = nullptr;
   ThreadStackHelper::Shutdown();
+#endif
 }
 
 BackgroundHangMonitor::BackgroundHangMonitor(const char* aName,
@@ -458,15 +464,19 @@ BackgroundHangMonitor::BackgroundHangMonitor(const char* aName,
                                              uint32_t aMaxTimeoutMs)
   : mThread(BackgroundHangThread::FindThread())
 {
+#ifdef MOZ_ENABLE_BACKGROUND_HANG_MONITOR
   if (!mThread) {
     mThread = new BackgroundHangThread(aName, aTimeoutMs, aMaxTimeoutMs);
   }
+#endif
 }
 
 BackgroundHangMonitor::BackgroundHangMonitor()
   : mThread(BackgroundHangThread::FindThread())
 {
+#ifdef MOZ_ENABLE_BACKGROUND_HANG_MONITOR
   MOZ_ASSERT(mThread, "Thread not initialized for hang monitoring");
+#endif
 }
 
 BackgroundHangMonitor::~BackgroundHangMonitor()
@@ -476,13 +486,17 @@ BackgroundHangMonitor::~BackgroundHangMonitor()
 void
 BackgroundHangMonitor::NotifyActivity()
 {
+#ifdef MOZ_ENABLE_BACKGROUND_HANG_MONITOR
   mThread->NotifyActivity();
+#endif
 }
 
 void
 BackgroundHangMonitor::NotifyWait()
 {
+#ifdef MOZ_ENABLE_BACKGROUND_HANG_MONITOR
   mThread->NotifyWait();
+#endif
 }
 
 

xpcom/threads/BackgroundHangMonitor.h

@@ -17,6 +17,11 @@ namespace Telemetry {
 class ThreadHangStats;
 };
 
+#ifndef RELEASE_BUILD
+// Undefine to disable background hang monitor
+#define MOZ_ENABLE_BACKGROUND_HANG_MONITOR
+#endif
+
 class BackgroundHangThread;
 
 /**