172390 2017-05-19 15:06:39 -0700 [iOS]: RunLoop::main().dispatch() needs to take into account USE_WEB_THREAD 2024-07-30 11:12:04 -0700 1 1 1 Unclassified WebKit WebCore Misc. WebKit Nightly Build Unspecified Unspecified NEW https://bugs.webkit.org/show_bug.cgi?id=277299 P2 Normal --- 1 joepeck webkit-unassigned aestes andersca beidson cdumez ddkilzer ggaren oldest_to_newest 1310793 0 joepeck 2017-05-19 15:06:39 -0700 [iOS]: RunLoop::main().dispatch() needs to take into account WEB_THREAD There are cases of RunLoop::main().dispatch() in WebCore that may not be safe if USE_WEB_THREAD bindings/js/SerializedScriptValue.cpp 3166: RunLoop::main().dispatch([this, conditionPtr = &condition, valuePtr = &value] { Modules/applepay/ApplePaySession.cpp 640: RunLoop::main().dispatch([promise, canMakePayments]() mutable { workers/WorkerMessagingProxy.cpp 168: RunLoop::main().dispatch([this, protectedThis = makeRef(*this), message = message.isolatedCopy()] { If possible callOnMainThread could be used or WebThreadRun. See Modules/websockets/WebSocket.cpp's approach. Note: WorkerMessagingProxy case, callOnMainThread couldn't be used and was specifically avoided. 1310885 1 aestes 2017-05-19 17:22:25 -0700 (In reply to Joseph Pecoraro from comment #0) > Modules/applepay/ApplePaySession.cpp > 640: RunLoop::main().dispatch([promise, canMakePayments]() > mutable { > In practice this is safe because Apple Pay is disabled at runtime in WebKit1 clients, so this code won't execute on a WebThread. I think callOnMainThread() could be used here without a problem, though. 1310906 2 andersca 2017-05-19 18:01:58 -0700 RunLoop::main().dispatch() shouldn't be web thread aware since it's used in the UI process. If anything, callOnMainThread should be used in WebCore. 1310913 3 cdumez 2017-05-19 18:19:57 -0700 The call to RunLoop::main().dispatch() in SerializedScriptValue.cpp for IndexedDB does look unsafe and should probably be replaced with callOnMainThread().