459581 - Recursive invocation of XPCCycleCollectGCCallback

Status: RESOLVED WORKSFORME

(Core :: XPConnect, defect)

Description

[Igor Bukanov]

During development for the bug 455548 I observed a recursive call to XPCCycleCollectGCCallback from js/src/xpconnect/src/nsXPConnect.cpp. It happens when the cycle collector triggers a release of nsJSContext when running in XPCCycleCollectGCCallback. That in turns leads to JS_DestroyContext call which in turns triggers the GC leading to a nested call to XPCCycleCollectGCCallback. Although it seems harmless on the pristine trunk, this may lead to some bad iterations with the cycle collector. 

Here is a typical stack trace:

#2  0x04d11ece in XPCCycleCollectGCCallback (cx=0xb7b0be00, status=JSGC_BEGIN) at /home/igor/m/31-ff/js/src/xpconnect/src/nsXPConnect.cpp:363
#3  0x001ddfeb in js_GC (cx=0xb7b0be00, gckind=GC_NORMAL) at /home/igor/m/31-ff/js/src/jsgc.cpp:3193
#4  0x001acd97 in js_DestroyContext (cx=0xb7b0be00, mode=JSDCM_FORCE_GC) at /home/igor/m/31-ff/js/src/jscntxt.cpp:462
#5  0x00193cf4 in JS_DestroyContext (cx=0xb7b0be00) at /home/igor/m/31-ff/js/src/jsapi.cpp:1058
#6  0x04d0ede7 in nsXPConnect::ReleaseJSContext (this=0xb7b15cf0, aJSContext=0xb7b0be00, noGC=0) at /home/igor/m/31-ff/js/src/xpconnect/src/nsXPConnect.cpp:2010
#7  0x03679309 in nsJSContext::Unlink (this=0xb367a740) at /home/igor/m/31-ff/dom/src/base/nsJSEnvironment.cpp:1286
#8  0x036793be in nsJSContext::cycleCollection::Unlink (this=0x3b6f788, p=0xb367a740) at /home/igor/m/31-ff/dom/src/base/nsJSEnvironment.cpp:1297
#9  0x003eddbf in nsCycleCollector::CollectWhite (this=0xb7bc1000) at /home/igor/m/31-ff/xpcom/base/nsCycleCollector.cpp:1666
#10 0x003ede93 in nsCycleCollector::FinishCollection (this=0xb7bc1000) at /home/igor/m/31-ff/xpcom/base/nsCycleCollector.cpp:2440
#11 0x003edf16 in nsCycleCollector_finishCollection () at /home/igor/m/31-ff/xpcom/base/nsCycleCollector.cpp:2922
#12 0x04d11f8e in XPCCycleCollectGCCallback (cx=0xb7b0a000, status=JSGC_END) at /home/igor/m/31-ff/js/src/xpconnect/src/nsXPConnect.cpp:387
#13 0x001df01b in js_GC (cx=0xb7b0a000, gckind=GC_NORMAL) at /home/igor/m/31-ff/js/src/jsgc.cpp:3734
#14 0x00190282 in JS_GC (cx=0xb7b0a000) at /home/igor/m/31-ff/js/src/jsapi.cpp:2477
#15 0x04d11e33 in nsXPConnect::Collect (this=0xb7b15cf0) at /home/igor/m/31-ff/js/src/xpconnect/src/nsXPConnect.cpp:466
#16 0x003ee463 in nsCycleCollector::Collect (this=0xb7bc1000, aTryCollections=1) at /home/igor/m/31-ff/xpcom/base/nsCycleCollector.cpp:2256
#17 0x003ee544 in nsCycleCollector_collect () at /home/igor/m/31-ff/xpcom/base/nsCycleCollector.cpp:2904
#18 0x036732bf in nsJSContext::CC () at /home/igor/m/31-ff/dom/src/base/nsJSEnvironment.cpp:3400
#19 0x036733f8 in nsJSContext::MaybeCC (aHigherProbability=0) at /home/igor/m/31-ff/dom/src/base/nsJSEnvironment.cpp:3452
#20 0x03673932 in nsUserActivityObserver::Observe (this=0xb6167ca0, aSubject=0x0, aTopic=0x3a54e6e "user-interaction-active", aData=0x0) at /home/igor/m/31-ff/dom/src/base/nsJSEnvironment.cpp:285
#21 0x0037ad7f in nsObserverList::NotifyObservers (this=0xb4a4bb3c, aSubject=0x0, aTopic=0x3a54e6e "user-interaction-active", someData=0x0) at /home/igor/m/31-ff/xpcom/ds/nsObserverList.cpp:128
#22 0x0037c221 in nsObserverService::NotifyObservers (this=0xb7b81b80, aSubject=0x0, aTopic=0x3a54e6e "user-interaction-active", someData=0x0) at /home/igor/m/31-ff/xpcom/ds/nsObserverService.cpp:181
#23 0x034a5dda in nsUITimerCallback::Notify (this=0xb60dd920, aTimer=0xb608c740) at /home/igor/m/31-ff/content/events/src/nsEventStateManager.cpp:221
#24 0x003dbdbd in nsTimerImpl::Fire (this=0xb608c740) at /home/igor/m/31-ff/xpcom/threads/nsTimerImpl.cpp:423
#25 0x003dbfd3 in nsTimerEvent::Run (this=0xae2d88a0) at /home/igor/m/31-ff/xpcom/threads/nsTimerImpl.cpp:512
#26 0x003d5841 in nsThread::ProcessNextEvent (this=0xb7b36ec0, mayWait=1, result=0xbf917c40) at /home/igor/m/31-ff/xpcom/threads/nsThread.cpp:510
#27 0x00363d90 in NS_ProcessNextEvent_P (thread=0xb7b36ec0, mayWait=1) at nsThreadUtils.cpp:227
#28 0x0523959e in nsBaseAppShell::Run (this=0xb7a6f6f0) at /home/igor/m/31-ff/widget/src/xpwidgets/nsBaseAppShell.cpp:170
#29 0x05358737 in nsAppStartup::Run (this=0xb7a9fac0) at /home/igor/m/31-ff/toolkit/components/startup/src/nsAppStartup.cpp:182
#30 0x0013e228 in XRE_main (argc=2, argv=0xbf918344, aAppData=0xb7b0e380) at /home/igor/m/31-ff/toolkit/xre/nsAppRunner.cpp:3263
#31 0x080496f2 in main (argc=2, argv=0xbf918344) at /home/igor/m/31-ff/browser/app/nsBrowserApp.cpp:156