Bug 138360 – Web Inspector: Stopwatch ASSERT when continuing inspector

• Component: Web Inspector
• Status: RESOLVED FIXED

[Joseph Pecoraro]

* SUMMARY
Stopwatch ASSERT when continuing inspector.

* TEST CASE
<script>
try {
    [].x.x
} catch (e) {
    console.log(e);
}
</script>

* STEPS TO REPRODUCE
1. Inspect Test Case
2. Enable Breakpoints on All Exceptions
3. Reload => hits breakpoint
4. Continue
  => ASSERT

ASSERTION FAILED: isnan(m_lastStartTime)
/Users/pecoraro/Build/Debug/usr/local/include/wtf/Stopwatch.h(67) : void WTF::Stopwatch::start()
1   0x116a218b0 WTFCrash
2   0x1165ee0c1 WTF::Stopwatch::start()
3   0x1165ec0da Inspector::InspectorDebuggerAgent::didContinue()
4   0x1165ec13c non-virtual thunk to Inspector::InspectorDebuggerAgent::didContinue()
5   0x11695ad95 Inspector::ScriptDebugServer::dispatchDidContinue(Inspector::ScriptDebugListener*)
6   0x11695b3c5 Inspector::ScriptDebugServer::dispatchFunctionToListeners(WTF::HashSet<Inspector::ScriptDebugListener*, WTF::PtrHash<Inspector::ScriptDebugListener*>, WTF::HashTraits<Inspector::ScriptDebugListener*> > const&, void (Inspector::ScriptDebugServer::*)(Inspector::ScriptDebugListener*))
7   0x11695b2cc Inspector::ScriptDebugServer::dispatchFunctionToListeners(void (Inspector::ScriptDebugServer::*)(Inspector::ScriptDebugListener*))
8   0x11695b66c Inspector::ScriptDebugServer::handlePause(JSC::Debugger::ReasonForPause, JSC::JSGlobalObject*)
9   0x116225500 JSC::Debugger::pauseIfNeeded(JSC::ExecState*)
10  0x11622578c JSC::Debugger::updateCallFrameAndPauseIfNeeded(JSC::ExecState*)
11  0x116225867 JSC::Debugger::exception(JSC::ExecState*, JSC::JSValue, bool)
12  0x11665d185 JSC::Interpreter::unwind(void*&, JSC::ExecState*&, JSC::JSValue&)
13  0x11667d49a JSC::genericUnwind(JSC::VM*, JSC::ExecState*, JSC::JSValue)
14  0x1167e7a9a llint_slow_path_handle_exception
15  0x1167f1201 llint_entry
16  0x1167eca69 vmEntryToJavaScript
17  0x116679e7a JSC::JITCode::execute(JSC::VM*, JSC::ProtoCallFrame*)
18  0x11665e6b4 JSC::Interpreter::execute(JSC::ProgramExecutable*, JSC::ExecState*, JSC::JSObject*)
19  0x1161fe3a0 JSC::evaluate(JSC::ExecState*, JSC::SourceCode const&, JSC::JSValue, JSC::JSValue*)
20  0x119051845 WebCore::JSMainThreadExecState::evaluate(JSC::ExecState*, JSC::SourceCode const&, JSC::JSValue, JSC::JSValue*)
21  0x119a3307d WebCore::ScriptController::evaluateInWorld(WebCore::ScriptSourceCode const&, WebCore::DOMWrapperWorld&)
22  0x119a331c4 WebCore::ScriptController::evaluate(WebCore::ScriptSourceCode const&)
23  0x119a42817 WebCore::ScriptElement::executeScript(WebCore::ScriptSourceCode const&)
24  0x119a417e0 WebCore::ScriptElement::prepareScript(WTF::TextPosition const&, WebCore::ScriptElement::LegacyTypeSupport)
25  0x118abb0d9 WebCore::HTMLScriptRunner::runScript(WebCore::Element*, WTF::TextPosition const&)
26  0x118abaee9 WebCore::HTMLScriptRunner::execute(WTF::PassRefPtr<WebCore::Element>, WTF::TextPosition const&)

[Radar WebKit Bug Importer]

<rdar://problem/18868233>

[Joseph Pecoraro]

Others have seen the ASSERT in Stopewatch::stop() as well due to a reload.

[Brian Burg]

I will look at this today.

[Joseph Pecoraro]

I'm hearing WebKit developers run into this frequently.

[Brian Burg]

Created attachment 244581 [details]
Patch

[Eric Carlson]

Comment on attachment 244581 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=244581&action=review

> Source/JavaScriptCore/ChangeLog:9
> +        We were unconditionally resuming the stopwatch even if we never
> +        never paused it in the first place. Maintain a flag for whether

Nit: "never never"

[Brian Burg]

Committed r178433: <http://trac.webkit.org/changeset/178433>