This is not surprising to me at all. The problem is even more complicated when you consider window.showModalDialog.
I recently changed Chromium to suppress WebKit's shared timer during calls to alert, confirm, prompt, and the beforeunload prompt. That may be why you aren't seeing the problem with one-shot timers. However, that's a hack since the same can't be done for showModalDialog. It would be better if we extended the PageGroupLoadDeferrer (bad name btw) to suspend the right set of timers / callbacks properly. -Darin On Mon, Mar 8, 2010 at 11:21 AM, Drew Wilson <atwil...@google.com> wrote: > Hi all, > > This weekend I spent some time trying to track down a regression caused by > r55593. In particular: > > http://trac.webkit.org/changeset/55593/trunk/WebCore/dom/Document.cpp > > This was a change to Document.postTask() to always use callOnMainThread() > (previously, calls to postTask() on the main thread were using one-shot > timers). > > We've since reverted r55593, but I've been playing around locally with that > same change to Document.postTask(), and I noticed that it *appeared* that > tasks posted via callOnMainThread() were still being executed even though > the main thread was displaying a javascript alert. The end result is that if > a worker thread was sending messages to the main thread via a message port, > the event handlers for incoming messages would still be invoked (so we'd run > javascript even though the javascript execution context should be blocked on > the alert()). In my test, I ended up trying to display nested alert() > dialogs, which resulted in a failed assertion. > > So, my question is: does it surprise anyone that tasks posted via > callOnMainThread() are getting executed even though there's a modal dialog > shown? And is there anything I should be doing in my task handler to make > sure we aren't re-entering JS execution inappropriately in these cases? I'm > just concerned that the way we're posting tasks from worker threads to the > main thread may cause reentrancy problems. > > Here's the stack from my nested call to alert(): > > #0 0x03ff073d in WebCore::DOMTimer::suspend (this=0x15c8a5b0) at > /Volumes/source/chrome.git/src/third_party/WebKit/WebCore/page/DOMTimer.cpp:181 > #1 0x046b2945 in WebCore::ScriptExecutionContext::suspendActiveDOMObjects > (this=0x81d8434) at > /Volumes/source/chrome.git/src/third_party/WebKit/WebCore/dom/ScriptExecutionContext.cpp:206 > #2 0x04538ae5 in WebCore::PageGroupLoadDeferrer::PageGroupLoadDeferrer > (this=0xbfffc6bc, page=0xc97940, deferSelf=true) at > /Volumes/source/chrome.git/src/third_party/WebKit/WebCore/page/PageGroupLoadDeferrer.cpp:47 > #3 0x03e0d977 in WebCore::Chrome::runJavaScriptAlert (this=0xc8ddb0, > frame=0x805a600, messa...@0xbfffc790) at > /Volumes/source/chrome.git/src/third_party/WebKit/WebCore/page/Chrome.cpp:264 > #4 0x03ff6c2c in WebCore::DOMWindow::alert (this=0x147e23f0, > messa...@0xbfffc790) at > /Volumes/source/chrome.git/src/third_party/WebKit/WebCore/page/DOMWindow.cpp:795 > #5 0x04266617 in WebCore::jsDOMWindowPrototypeFunctionAlert > (exec=0x14f0c1b0, thisValue={u = {asEncodedJSValue = -8455721472, asDouble = > -nan(0xffffe07ffee00), asBits = {payload = 134213120, tag = -2}}}, > ar...@0xbfffc7bc) at > /Volumes/source/chrome.git/src/third_party/WebKit/WebKitBuild/Debug/DerivedSources/WebCore/JSDOMWindow.cpp:8320 > #6 0x00d8b166 in ?? () > #7 0x0070bd6b in JSC::JITCode::execute (this=0x147a7690, > registerFile=0x1473a7fc, callFrame=0x14f0c150, globalData=0x818e800, > exception=0x818f60c) at JITCode.h:77 > #8 0x006f542f in JSC::Interpreter::execute (this=0x1473a7f0, > functionExecutable=0x147a7680, callFrame=0x81ed664, function=0x7fd5400, > thisObj=0x7fd5200, ar...@0xbfffca64, scopeChain=0x147a8920, > exception=0x818f60c) at > /Volumes/source/chrome.git/src/third_party/WebKit/JavaScriptCore/interpreter/Interpreter.cpp:687 > #9 0x0074d767 in JSC::JSFunction::call (this=0x7fd5400, exec=0x81ed664, > thisValue={u = {asEncodedJSValue = -8455892480, asDouble = > -nan(0xffffe07fd5200), asBits = {payload = 134042112, tag = -2}}}, > ar...@0xbfffca64) at > /Volumes/source/chrome.git/src/third_party/WebKit/JavaScriptCore/runtime/JSFunction.cpp:122 > #10 0x0069d481 in JSC::call (exec=0x81ed664, functionObject={u = > {asEncodedJSValue = -8455891968, asDouble = -nan(0xffffe07fd5400), asBits = > {payload = 134042624, tag = -2}}}, callType=JSC::CallTypeJS, > callda...@0xbfffca34, thisValue={u = {asEncodedJSValue = -8455892480, > asDouble = -nan(0xffffe07fd5200), asBits = {payload = 134042112, tag = > -2}}}, ar...@0xbfffca64) at > /Volumes/source/chrome.git/src/third_party/WebKit/JavaScriptCore/runtime/CallData.cpp:39 > #11 0x0429f5bb in WebCore::JSEventListener::handleEvent (this=0x15c31ef0, > scriptExecutionContext=0x81d8434, event=0xc34d40) at > /Volumes/source/chrome.git/src/third_party/WebKit/WebCore/bindings/js/JSEventListener.cpp:115 > #12 0x04037da0 in WebCore::EventTarget::fireEventListeners > (this=0x15c9c400, event=0xc34d40) at > /Volumes/source/chrome.git/src/third_party/WebKit/WebCore/dom/EventTarget.cpp:297 > #13 0x04037e88 in WebCore::EventTarget::dispatchEvent (this=0x15c9c400, > eve...@0xbfffcbac) at > /Volumes/source/chrome.git/src/third_party/WebKit/WebCore/dom/EventTarget.cpp:262 > #14 0x0403769a in WebCore::EventTarget::dispatchEvent (this=0x15c9c400, > eve...@0xbfffcc2c, e...@0xbfffcbfc) at > /Volumes/source/chrome.git/src/third_party/WebKit/WebCore/dom/EventTarget.cpp:254 > #15 0x044eeaa8 in WebCore::MessagePort::dispatchMessages (this=0x15c9c400) > at > /Volumes/source/chrome.git/src/third_party/WebKit/WebCore/dom/MessagePort.cpp:177 > #16 0x046b3173 in > WebCore::ScriptExecutionContext::dispatchMessagePortEvents (this=0x81d8434) > at > /Volumes/source/chrome.git/src/third_party/WebKit/WebCore/dom/ScriptExecutionContext.cpp:162 > #17 0x046b7a63 in WebCore::ProcessMessagesSoonTask::performTask > (this=0x147d36f0, context=0x81d8434) at > /Volumes/source/chrome.git/src/third_party/WebKit/WebCore/dom/ScriptExecutionContext.cpp:56 > #18 0x03f4781a in WebCore::performTask (ctx=0x15d12cd0) at > /Volumes/source/chrome.git/src/third_party/WebKit/WebCore/dom/Document.cpp:4726 > #19 0x00776c1e in WTF::dispatchFunctionsFromMainThread () at > /Volumes/source/chrome.git/src/third_party/WebKit/JavaScriptCore/wtf/MainThread.cpp:96 > #20 0x0077766f in -[WTFMainThreadCaller call] (self=0xc1b2e0, > _cmd=0x848956) at > /Volumes/source/chrome.git/src/third_party/WebKit/JavaScriptCore/wtf/mac/MainThreadMac.mm:44 > #21 0x904549ac in __NSThreadPerformPerform () > #22 0x973903c5 in CFRunLoopRunSpecific () > #23 0x97390aa8 in CFRunLoopRunInMode () > #24 0x90c982ac in RunCurrentEventLoopInMode () > #25 0x90c97ffe in ReceiveNextEventCommon () > #26 0x90c97f39 in BlockUntilNextEventMatchingListInMode () > #27 0x960b76d5 in _DPSNextEvent () > #28 0x960b6f88 in -[NSApplication > nextEventMatchingMask:untilDate:inMode:dequeue:] () > #29 0x0000c045 in ?? () > #30 0x962f438d in -[NSApplication _realDoModalLoop:peek:] () > #31 0x962eeacb in -[NSApplication runModalForWindow:] () > #32 0x00113e5d in ?? () > #33 0x00113cf4 in ?? () > #34 0x000c7118 in ?? () > #35 0x000c7044 in ?? () > #36 0x00303030 in CallDelegate (self=0xc93db0, delegate=0xc93db0, > selector=0x3d0268, object1=0x15c15868, object2=0xc99770) at > /Volumes/source/chrome.git/src/third_party/WebKit/WebKit/mac/WebView/WebDelegateImplementationCaching.mm:131 > #37 0x003030b9 in CallUIDelegate (self=0xc93db0, selector=0x3d0268, > object1=0x15c15868, object2=0xc99770) at > /Volumes/source/chrome.git/src/third_party/WebKit/WebKit/mac/WebView/WebDelegateImplementationCaching.mm:440 > #38 0x002f6e60 in WebChromeClient::runJavaScriptAlert (this=0xc59020, > frame=0x805a600, messa...@0xbfffdfbc) at > /Volumes/source/chrome.git/src/third_party/WebKit/WebKit/mac/WebCoreSupport/WebChromeClient.mm:368 > #39 0x03e0d9fb in WebCore::Chrome::runJavaScriptAlert (this=0xc8ddb0, > frame=0x805a600, messa...@0xbfffe040) at > /Volumes/source/chrome.git/src/third_party/WebKit/WebCore/page/Chrome.cpp:267 > #40 0x03ff6c2c in WebCore::DOMWindow::alert (this=0x147e23f0, > messa...@0xbfffe040) at > /Volumes/source/chrome.git/src/third_party/WebKit/WebCore/page/DOMWindow.cpp:795 > #41 0x04266617 in WebCore::jsDOMWindowPrototypeFunctionAlert > (exec=0x14f0c0a8, thisValue={u = {asEncodedJSValue = -8455721472, asDouble = > -nan(0xffffe07ffee00), asBits = {payload = 134213120, tag = -2}}}, > ar...@0xbfffe06c) at > /Volumes/source/chrome.git/src/third_party/WebKit/WebKitBuild/Debug/DerivedSources/WebCore/JSDOMWindow.cpp:8320 > #42 0x00d8b166 in ?? () > #43 0x0070bd6b in JSC::JITCode::execute (this=0x147067f0, > registerFile=0x1473a7fc, callFrame=0x14f0c050, globalData=0x818e800, > exception=0x818f60c) at JITCode.h:77 > #44 0x006f542f in JSC::Interpreter::execute (this=0x1473a7f0, > functionExecutable=0x147067e0, callFrame=0x81ed664, function=0x7fc2440, > thisObj=0x7fc22c0, ar...@0xbfffe314, scopeChain=0x147bc080, > exception=0x818f60c) at > /Volumes/source/chrome.git/src/third_party/WebKit/JavaScriptCore/interpreter/Interpreter.cpp:687 > #45 0x0074d767 in JSC::JSFunction::call (this=0x7fc2440, exec=0x81ed664, > thisValue={u = {asEncodedJSValue = -8455970112, asDouble = > -nan(0xffffe07fc22c0), asBits = {payload = 133964480, tag = -2}}}, > ar...@0xbfffe314) at > /Volumes/source/chrome.git/src/third_party/WebKit/JavaScriptCore/runtime/JSFunction.cpp:122 > #46 0x0069d481 in JSC::call (exec=0x81ed664, functionObject={u = > {asEncodedJSValue = -8455969728, asDouble = -nan(0xffffe07fc2440), asBits = > {payload = 133964864, tag = -2}}}, callType=JSC::CallTypeJS, > callda...@0xbfffe2e4, thisValue={u = {asEncodedJSValue = -8455970112, > asDouble = -nan(0xffffe07fc22c0), asBits = {payload = 133964480, tag = > -2}}}, ar...@0xbfffe314) at > /Volumes/source/chrome.git/src/third_party/WebKit/JavaScriptCore/runtime/CallData.cpp:39 > #47 0x0429f5bb in WebCore::JSEventListener::handleEvent (this=0xcb2aa0, > scriptExecutionContext=0x81d8434, event=0x15d08b90) at > /Volumes/source/chrome.git/src/third_party/WebKit/WebCore/bindings/js/JSEventListener.cpp:115 > #48 0x04037da0 in WebCore::EventTarget::fireEventListeners > (this=0x1478c1e4, event=0x15d08b90) at > /Volumes/source/chrome.git/src/third_party/WebKit/WebCore/dom/EventTarget.cpp:297 > #49 0x04037e88 in WebCore::EventTarget::dispatchEvent (this=0x1478c1e4, > eve...@0xbfffe470) at > /Volumes/source/chrome.git/src/third_party/WebKit/WebCore/dom/EventTarget.cpp:262 > #50 0x04878a40 in WebCore::MessageWorkerTask::performTask (this=0x1470bb20, > scriptContext=0x81d8434) at > /Volumes/source/chrome.git/src/third_party/WebKit/WebCore/workers/WorkerMessagingProxy.cpp:97 > #51 0x03f4781a in WebCore::performTask (ctx=0x15d12cb0) at > /Volumes/source/chrome.git/src/third_party/WebKit/WebCore/dom/Document.cpp:4726 > #52 0x00776c1e in WTF::dispatchFunctionsFromMainThread () at > /Volumes/source/chrome.git/src/third_party/WebKit/JavaScriptCore/wtf/MainThread.cpp:96 > #53 0x0077766f in -[WTFMainThreadCaller call] (self=0xc1b2e0, > _cmd=0x848956) at > /Volumes/source/chrome.git/src/third_party/WebKit/JavaScriptCore/wtf/mac/MainThreadMac.mm:44 > #54 0x904549ac in __NSThreadPerformPerform () > #55 0x973903c5 in CFRunLoopRunSpecific () > #56 0x97390aa8 in CFRunLoopRunInMode () > #57 0x90c982ac in RunCurrentEventLoopInMode () > #58 0x90c980c5 in ReceiveNextEventCommon () > #59 0x90c97f39 in BlockUntilNextEventMatchingListInMode () > #60 0x960b76d5 in _DPSNextEvent () > #61 0x960b6f88 in -[NSApplication > nextEventMatchingMask:untilDate:inMode:dequeue:] () > #62 0x0000c045 in ?? () > #63 0x960aff9f in -[NSApplication run] () > #64 0x9607d1d8 in NSApplicationMain () > #65 0x000029d2 in ?? () > Current language: auto; currently c++ > > _______________________________________________ > webkit-dev mailing list > webkit-dev@lists.webkit.org > http://lists.webkit.org/mailman/listinfo.cgi/webkit-dev > >
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