Recently I encountered a WebKit crash problem, it is related to thread checking
0 WebKit WTFCrashWithInfo(int, char const*, char const*, int)()
1 WebKit WebKit::isMainThreadOrCheckDisabled()()
2 WebKit WebKit::WebProcessPool::createNewWebProcess(WebKit::WebsiteDataStore*, WebKit::WebProcessProxy::IsPrewarmed)()
3 WebKit WebKit::WebProcessPool::processForRegistrableDomain(WebKit::WebsiteDataStore&, WebKit::WebPageProxy*, WebCore::RegistrableDomain const&)()
4 WebKit WebKit::WebProcessPool::createWebPage(WebKit::PageClient&, WTF::Ref<API::PageConfiguration, WTF::DumbPtrTraits<API::PageConfiguration> >&&)()
5 WebKit -[WKContentView _commonInitializationWithProcessPool:configuration:]()
6 WebKit -[WKContentView initWithFrame:processPool:configuration:webView:]()
7 WebKit -[WKWebView _initializeWithConfiguration:]()
8 WebKit -[WKWebView initWithFrame:configuration:]()
I am sure the WKWebView was initialized on Main Thread, but isMainThreadOrCheckDisabled shows isn't. I even read the source code of WebKit, not able to find isMainThreadOrCheckDisabled be called in createNewWebProcess ,so do you have any idea?
After further reading the source code of WebKit, I find out
isMainThreadOrCheckDisabled check thread by RunLoop actually, which is
bool RunLoop::isMain()
{
ASSERT(s_mainRunLoop);
return s_mainRunLoop == &RunLoop::current();
}
and the &RunLoop::current() represents current thread， so s_mainRunLoop means Main Thread, because it is initialized on it
void RunLoop::initializeMain()
{
RELEASE_ASSERT(!s_mainRunLoop);
s_mainRunLoop = &RunLoop::current();
}
So, when run isMainThreadOrCheckDisabled on a background thread, it return false.
But the crash I encountered was happened on Main Thread, dose it means s_mainRunLoop not initialized on Main Thread? Or, is there any situation can WebKit be initialized on background thread?
