Bug 1138520 - Diagnostic patch for shutdown hangs (r=jchen)

dom/ipc/ContentParent.cpp

@@ -1881,6 +1881,9 @@ struct DelayedDeleteContentParentTask : public nsRunnable
 void
 ContentParent::ActorDestroy(ActorDestroyReason why)
 {
+    CrashReporter::AnnotateCrashReport(NS_LITERAL_CSTRING("ChildShutdownState"),
+                                       NS_LITERAL_CSTRING("ActorDestroy"));
+
     if (mForceKillTimer) {
         mForceKillTimer->Cancel();
         mForceKillTimer = nullptr;
@@ -2042,6 +2045,12 @@ ContentParent::NotifyTabDestroying(PBrowserParent* aTab)
     StartForceKillTimer();
 }
 
+static int32_t
+ForceKillTimeout()
+{
+    return Preferences::GetInt("dom.ipc.tabs.shutdownTimeoutSecs", 5);
+}
+
 void
 ContentParent::StartForceKillTimer()
 {
@@ -2049,8 +2058,7 @@ ContentParent::StartForceKillTimer()
         return;
     }
 
-    int32_t timeoutSecs =
-        Preferences::GetInt("dom.ipc.tabs.shutdownTimeoutSecs", 5);
+    int32_t timeoutSecs = ForceKillTimeout();
     if (timeoutSecs > 0) {
         mForceKillTimer = do_CreateInstance("@mozilla.org/timer;1");
         MOZ_ASSERT(mForceKillTimer);
@@ -2882,13 +2890,25 @@ ContentParent::Observe(nsISupports* aSubject,
 {
     if (mSubprocess && (!strcmp(aTopic, "profile-before-change") ||
                         !strcmp(aTopic, "xpcom-shutdown"))) {
+        CrashReporter::AnnotateCrashReport(NS_LITERAL_CSTRING("ChildShutdownState"),
+                                           NS_LITERAL_CSTRING("Begin"));
+
         // Okay to call ShutDownProcess multiple times.
         ShutDownProcess(SEND_SHUTDOWN_MESSAGE);
 
+        int32_t timeout = ForceKillTimeout();
+
+        // Make sure we have a KillHard timer before we start waiting.
+        MOZ_RELEASE_ASSERT(!timeout || !mIPCOpen || mCalledKillHard || mForceKillTimer);
+
         // Wait for shutdown to complete, so that we receive any shutdown
         // data (e.g. telemetry) from the child before we quit.
         // This loop terminate prematurely based on mForceKillTimer.
         while (mIPCOpen) {
+            // If we clear the KillHard timer, it should only be because we
+            // called KillHard. In that case, ActorDestroy should happen
+            // momentarily.
+            MOZ_RELEASE_ASSERT(!timeout || mCalledKillHard || mForceKillTimer);
             NS_ProcessNextEvent(nullptr, true);
         }
         NS_ASSERTION(!mSubprocess, "Close should have nulled mSubprocess");
@@ -3335,6 +3355,9 @@ ContentParent::ForceKillTimerCallback(nsITimer* aTimer, void* aClosure)
 void
 ContentParent::KillHard(const char* aReason)
 {
+    CrashReporter::AnnotateCrashReport(NS_LITERAL_CSTRING("ChildShutdownState"),
+                                       NS_LITERAL_CSTRING("KillHard"));
+
     // On Windows, calling KillHard multiple times causes problems - the
     // process handle becomes invalid on the first call, causing a second call
     // to crash our process - more details in bug 890840.

testing/profiles/prefs_general.js

@@ -318,4 +318,4 @@ user_pref("network.proxy.pac_generator", false);
 // Make tests run consistently on DevEdition (which has a lightweight theme
 // selected by default).
 user_pref("lightweightThemes.selectedThemeID", "");
-user_pref("browser.devedition.theme.enabled", false);
+user_pref("browser.devedition.theme.enabled", false);