Bug 308430 – [threaded-animations] deadlock under `RemoteLayerTreeEventDispatcher::scrollingTreeWasRecentlyActive()`

• Status: RESOLVED
• Resolution: FIXED
• Component: Animations

[Antoine Quint]

A new test being added for bug 308429 yields a deadlock if ran over multiple iterations using this command:

run-webkit-tests --debug --iterations 1000 webanimations/threaded-animations/accelerated-timeline-preservation-during-update.html

```
Thread 0::  Dispatch queue: com.apple.main-thread
0   libsystem_kernel.dylib        	       0x18cd4b50c __psynch_cvwait + 8
1   libsystem_pthread.dylib       	       0x18cd8c128 _pthread_psynch_cond_wait + 92 [inlined]
2   libsystem_pthread.dylib       	       0x18cd8c128 _pthread_cond_wait + 980
3   JavaScriptCore                	       0x10d81e784 WTF::ThreadCondition::wait(WTF::Mutex&) + 52
4   JavaScriptCore                	       0x10d8146e8 WTF::ThreadCondition::timedWait(WTF::Mutex&, WTF::WallTime) + 144
5   JavaScriptCore                	       0x10d740f00 WTF::ParkingLot::parkConditionallyImpl(void const*, WTF::ScopedLambda<bool ()> const&, WTF::ScopedLambda<void ()> const&, WTF::TimeWithDynamicClockType const&) + 500
6   JavaScriptCore                	       0x10d98798c WTF::ParkingLot::ParkResult WTF::ParkingLot::parkConditionally<WTF::ParkingLot::ParkResult WTF::ParkingLot::compareAndPark<unsigned char, unsigned char>(WTF::Atomic<unsigned char> const*, unsigned char)::'lambda'(), WTF::ParkingLot::ParkResult WTF::ParkingLot::compareAndPark<unsigned char, unsigned char>(WTF::Atomic<unsigned char> const*, unsigned char)::'lambda0'()>(void const*, unsigned char const&, unsigned char const&, WTF::TimeWithDynamicClockType const&) + 92
7   JavaScriptCore                	       0x10d987914 WTF::ParkingLot::ParkResult WTF::ParkingLot::compareAndPark<unsigned char, unsigned char>(WTF::Atomic<unsigned char> const*, unsigned char) + 100
8   JavaScriptCore                	       0x10d734cf4 WTF::LockAlgorithm<unsigned char, (unsigned char)1, (unsigned char)2, WTF::EmptyLockHooks<unsigned char>>::lockSlow(WTF::Atomic<unsigned char>&) + 388
9   JavaScriptCore                	       0x10d734b5c WTF::Lock::lockSlow() + 48
10  WebKit                        	       0x12cf06b74 WTF::Lock::lock() + 48 (Lock.h:71)
11  WebKit                        	       0x12cf06b20 WTF::Locker<WTF::Lock>::Locker(WTF::Lock&) + 64 (Locker.h:87)
12  WebKit                        	       0x12cf06aa0 WTF::Locker<WTF::Lock>::Locker(WTF::Lock&) + 40 (Locker.h:86)
13  WebKit                        	       0x13004159c WebKit::RemoteLayerTreeEventDispatcher::scrollingTreeWasRecentlyActive() + 196
14  WebKit                        	       0x13004166c WebKit::RemoteLayerTreeEventDispatcher::mainThreadDisplayDidRefresh(unsigned int) + 36
15  WebKit                        	       0x130045a20 WebKit::RemoteScrollingCoordinatorProxyMac::displayDidRefresh(unsigned int) + 44
16  WebKit                        	       0x13003b25c WebKit::RemoteLayerTreeDrawingAreaProxyMac::didRefreshDisplay() + 648
17  WebKit                        	       0x13005ef28 WebKit::RemoteLayerTreeDisplayLinkClient::displayLinkFired(unsigned int, WebCore::DisplayUpdate, bool, bool)::$_0::operator()() const + 236
18  WebKit                        	       0x13005ee00 WTF::Detail::CallableWrapper<WebKit::RemoteLayerTreeDisplayLinkClient::displayLinkFired(unsigned int, WebCore::DisplayUpdate, bool, bool)::$_0, void>::call() + 32
19  JavaScriptCore                	       0x10d8fdca4 WTF::Function<void ()>::operator()() const + 172
20  JavaScriptCore                	       0x10d7dd75c WTF::RunLoop::performWork() + 284
21  JavaScriptCore                	       0x10d7dd62c WTF::RunLoop::performWork(void*) + 40
22  CoreFoundation                	       0x18ce48b90 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 28
23  CoreFoundation                	       0x18ce48b24 __CFRunLoopDoSource0 + 172
24  CoreFoundation                	       0x18ce48890 __CFRunLoopDoSources0 + 232
25  CoreFoundation                	       0x18ce474b4 __CFRunLoopRun + 820
26  CoreFoundation                	       0x18cf19c8c _CFRunLoopRunSpecificWithOptions + 532
27  Foundation                    	       0x18e690b44 -[NSRunLoop(NSRunLoop) runMode:beforeDate:] + 212
28  WebKitTestRunner              	       0x1048229d0 WTR::TestController::platformRunUntil(bool&, WTF::Seconds) + 300 (TestControllerCocoa.mm:436)
29  WebKitTestRunner              	       0x1047c7894 WTR::TestController::runUntil(bool&, WTF::Seconds) + 88 (TestController.cpp:3003)
30  WebKitTestRunner              	       0x10483b28c WTR::TestInvocation::invoke() + 436 (TestInvocation.cpp:207)
31  WebKitTestRunner              	       0x1047d7300 WTR::TestController::runTest(char const*) + 576 (TestController.cpp:2933)
32  WebKitTestRunner              	       0x1047d7a94 WTR::TestController::runTestingServerLoop() + 272 (TestController.cpp:2979)
33  WebKitTestRunner              	       0x1047c8540 WTR::TestController::run() + 48 (TestController.cpp:2987)
34  WebKitTestRunner              	       0x1047c7c24 WTR::TestController::TestController(int, char const**) + 888 (TestController.cpp:238)
35  WebKitTestRunner              	       0x1047c860c WTR::TestController::TestController(int, char const**) + 48 (TestController.cpp:235)
36  WebKitTestRunner              	       0x10475dc70 main + 128 (main.mm:79)
37  dyld                          	       0x18c9cfda4 start + 6992
```

[Radar WebKit Bug Importer]

<rdar://problem/170919668>

[Antoine Quint]

After 308011@main, which added the flaky crash expectation for this bug, it's necessary to run the test with `--force` as well. This does the trick for me:

run-wekit-tests --debug --iterations 1000 webanimations/threaded-animations/accelerated-timeline-preservation-during-update.html --exit-after-n-crashes 1 --force

[Matt Woodrow]

Pull request: https://github.com/WebKit/WebKit/pull/59382

[EWS]

Committed 308238@main (3dc29411a3ca): <https://commits.webkit.org/308238@main>

Reviewed commits have been landed. Closing PR #59382 and removing active labels.