Bug 1299934 - Run shutdown collection in workers in opt builds. r=froydnj,smaug

We skip running shutdown collection on the main thread, because we're
exiting right after, but the process still continues when we shut down
a worker, so we should always do collections there.

MozReview-Commit-ID: IQZItm1qWXW

--HG--
extra : rebase_source : 4fd89e36db124a524c240e806a885dee3b68979e

xpcom/base/nsCycleCollector.cpp

@@ -1330,7 +1330,7 @@ public:
                SliceBudget& aBudget,
                nsICycleCollectorListener* aManualListener,
                bool aPreferShorterSlices = false);
-  void Shutdown();
+  void Shutdown(bool aDoCollect);
 
   bool IsIdle() const { return mIncrementalPhase == IdlePhase; }
 
@@ -3876,17 +3876,14 @@ nsCycleCollector::SuspectedCount()
 }
 
 void
-nsCycleCollector::Shutdown()
+nsCycleCollector::Shutdown(bool aDoCollect)
 {
   CheckThreadSafety();
 
   // Always delete snow white objects.
   FreeSnowWhite(true);
 
-#ifndef NS_FREE_PERMANENT_DATA
-  if (PR_GetEnv("MOZ_CC_RUN_DURING_SHUTDOWN"))
-#endif
-  {
+  if (aDoCollect) {
     ShutdownCollect();
   }
 }
@@ -4196,7 +4193,7 @@ nsCycleCollector_finishAnyCurrentCollection()
 }
 
 void
-nsCycleCollector_shutdown()
+nsCycleCollector_shutdown(bool aDoCollect)
 {
   CollectorData* data = sCollectorData.get();
 
@@ -4205,7 +4202,7 @@ nsCycleCollector_shutdown()
     PROFILER_LABEL("nsCycleCollector", "shutdown",
                    js::ProfileEntry::Category::CC);
 
-    data->mCollector->Shutdown();
+    data->mCollector->Shutdown(aDoCollect);
     data->mCollector = nullptr;
     if (data->mRuntime) {
       // Run any remaining tasks that may have been enqueued via

xpcom/base/nsCycleCollector.h

@@ -51,7 +51,10 @@ void nsCycleCollector_collectSlice(js::SliceBudget& budget,
                                    bool aPreferShorterSlices = false);
 
 uint32_t nsCycleCollector_suspectedCount();
-void nsCycleCollector_shutdown();
+
+// If aDoCollect is true, then run the GC and CC a few times before
+// shutting down the CC completely.
+void nsCycleCollector_shutdown(bool aDoCollect = true);
 
 // Helpers for interacting with JS
 void nsCycleCollector_registerJSRuntime(mozilla::CycleCollectedJSRuntime* aRt);

xpcom/build/XPCOMInit.cpp

@@ -984,7 +984,13 @@ ShutdownXPCOM(nsIServiceManager* aServMgr)
     moduleLoaders = nullptr;
   }
 
-  nsCycleCollector_shutdown();
+  bool shutdownCollect;
+#ifdef NS_FREE_PERMANENT_DATA
+  shutdownCollect = true;
+#else
+  shutdownCollect = !!PR_GetEnv("MOZ_CC_RUN_DURING_SHUTDOWN");
+#endif
+  nsCycleCollector_shutdown(shutdownCollect);
 
   PROFILER_MARKER("Shutdown xpcom");
   // If we are doing any shutdown checks, poison writes.