Regression(r253213) Load hang and high CPU usage when trying to load myuhc.com
https://bugs.webkit.org/show_bug.cgi?id=206315
<rdar://problem/58139842>
Reviewed by Geoffrey Garen.
Source/WebCore:
Starting in r253213, we now throw when trying to do a sync XHR during unload. Unfortunately, this is confusing the script
on myuhc.com and it ends up retrying the sync XHR in a tight loop. To address the issue, I am putting in a safety net which
ignores calls to XMLHttpRequest.send() instead of throwing, once we've reached 5 sync XHR failures during unload.
Throwing is useful because this gives a change for Web authors to fall back to using Beacon API or Fetch KeepAlive if the
sync XHR fails. There is already code out there doing just that. You could imagine content doing more than one sync XHR
during unload, each one with a good beacon API fallback. For this reason, I put in a limit of 5 sync failures before
we stop throwing. Having a limit is important to break bad loops when the content simply retries the same sync XHR load
when the sync XHR send() call throws.
Tests: fast/xmlhttprequest/xmlhttprequest-multiple-sync-xhr-during-unload.html
fast/xmlhttprequest/xmlhttprequest-sync-xhr-failure-loop-during-unload.html
* dom/Document.cpp:
(WebCore::Document::didRejectSyncXHRDuringPageDismissal):
(WebCore::Document::shouldIgnoreSyncXHRs const):
* dom/Document.h:
* loader/DocumentThreadableLoader.cpp:
(WebCore::DocumentThreadableLoader::DocumentThreadableLoader):
* xml/XMLHttpRequest.cpp:
(WebCore::XMLHttpRequest::prepareToSend):
LayoutTests:
Add layout test coverage.
* fast/xmlhttprequest/resources/xmlhttprequest-multiple-sync-xhr-during-unload-iframe.html: Added.
* fast/xmlhttprequest/resources/xmlhttprequest-sync-xhr-failure-loop-during-unload-iframe.html: Added.
* fast/xmlhttprequest/xmlhttprequest-multiple-sync-xhr-during-unload-expected.txt: Added.
* fast/xmlhttprequest/xmlhttprequest-multiple-sync-xhr-during-unload.html: Added.
* fast/xmlhttprequest/xmlhttprequest-sync-xhr-failure-loop-during-unload-expected.txt: Added.
* fast/xmlhttprequest/xmlhttprequest-sync-xhr-failure-loop-during-unload.html: Added.
git-svn-id: http://svn.webkit.org/repository/webkit/trunk@254652 268f45cc-cd09-0410-ab3c-d52691b4dbfc
diff --git a/Source/WebCore/loader/DocumentThreadableLoader.cpp b/Source/WebCore/loader/DocumentThreadableLoader.cpp
index 1e3cffa..64ee5dd 100644
--- a/Source/WebCore/loader/DocumentThreadableLoader.cpp
+++ b/Source/WebCore/loader/DocumentThreadableLoader.cpp
@@ -133,6 +133,7 @@
ASSERT(m_async || m_referrer.isEmpty());
if (document.settings().disallowSyncXHRDuringPageDismissalEnabled() && !m_async && (!document.page() || !document.page()->areSynchronousLoadsAllowed())) {
+ document.didRejectSyncXHRDuringPageDismissal();
logErrorAndFail(ResourceError(errorDomainWebKitInternal, 0, request.url(), "Synchronous loads are not allowed at this time"));
return;
}
