Bug 161291 – REGRESSION (r193286): Promise chain no longer prevent UI refresh

• Status: RESOLVED
• Resolution: FIXED
• Component: WebCore Misc.

[Kvet]

In Safari 10, Safari Technology Preview and Webkit Nightly Build behavour of native Promise object changed from that one in Safari 9.

Now during microtasks execution there are unnecessary UI updates. This change can break existing codebase because all (latest Chrome, FireFox, IE, Edge) browsers that support Promise object behaves correctly. Even promise polyfill in checked browsers (IE9, Android 4 Browser) works correctly. I assume that this is very critical bug in Safari 10 that breaks down compatibility with another browsers.

Issue can be reproduced in https://jsfiddle.net/Lo7utx4s/ . Clicking on 'TEST PROMISE BEHAVIOR' should not cause blue rectangle blinks with white or black.

[Alexey Proskuryakov]

Regressed in https://trac.webkit.org/changeset/193286

[Radar WebKit Bug Importer]

<rdar://problem/28062149>

[Jake Archibald]

This causes setTimeout to fire before promises in some cases. Demo: http://output.jsbin.com/xenumo/quiet

[Sam Weinig]

Created attachment 300971 [details]
Patch

[Geoffrey Garen]

Comment on attachment 300971 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=300971&action=review

r=me

> Source/WebCore/dom/Microtasks.cpp:81
> +    Vector<std::unique_ptr<Microtask>> toKeep;
> +    do {

I think this would be better as a while loop, since the queue can be initially empty at a checkpoint, right?

[Geoffrey Garen]

Mac bot:

Regressions: Unexpected text-only failures (4)
  imported/w3c/web-platform-tests/custom-elements/adopted-callback.html [ Failure ]
  imported/w3c/web-platform-tests/custom-elements/upgrading.html [ Failure ]
  imported/w3c/web-platform-tests/html/webappapis/scripting/event-loops/microtask_after_script.html [ Failure ]
  js/dom/modules/module-incorrect-relative-specifier.html [ Failure ]

[Build Bot]

Comment on attachment 300971 [details]
Patch

Attachment 300971 [details] did not pass mac-ews (mac):
Output: http://webkit-queues.webkit.org/results/3027786

New failing tests:
imported/w3c/web-platform-tests/html/webappapis/scripting/event-loops/microtask_after_script.html
imported/w3c/web-platform-tests/custom-elements/upgrading.html
js/dom/modules/module-incorrect-relative-specifier.html
imported/w3c/web-platform-tests/custom-elements/adopted-callback.html

[Build Bot]

Created attachment 300976 [details]
Archive of layout-test-results from ews103 for mac-elcapitan

The attached test failures were seen while running run-webkit-tests on the mac-ews.
Bot: ews103  Port: mac-elcapitan  Platform: Mac OS X 10.11.6

[Sam Weinig]

Created attachment 300978 [details]
Patch

[Sam Weinig]

Committed r211913: <http://trac.webkit.org/changeset/211913>

[Chris Dumez]

This change may have caused:
https://build.webkit.org/results/Apple%20Sierra%20Release%20WK2%20(Tests)/r211913%20(3409)/http/tests/misc/module-absolute-url-pretty-diff.html

[Yusuke Suzuki]

(In reply to comment #11)
> This change may have caused:
> https://build.webkit.org/results/Apple%20Sierra%20Release%20WK2%20(Tests)/
> r211913%20(3409)/http/tests/misc/module-absolute-url-pretty-diff.html

I'll land the fix for that.

[Yusuke Suzuki]

Committed r211968: <http://trac.webkit.org/changeset/211968>

[Ryan Haddad]

It also looks like it caused http/tests/cache/disk-cache/disk-cache-remove-several-pending-writes.html to fail: 

https://build.webkit.org/results/Apple%20iOS%2010%20Simulator%20Release%20WK2%20(Tests)/r211961%20(3594)/http/tests/cache/disk-cache/disk-cache-remove-several-pending-writes-pretty-diff.html

[Antti Koivisto]

I would suspect r211963 for that.

[Ryan Haddad]

(In reply to comment #15)
> I would suspect r211963 for that.

Flakiness dashboard suggests that it happened between these changes: https://trac.webkit.org/log/?verbose=on&rev=211915&stop_rev=211913

https://webkit-test-results.webkit.org/dashboards/flakiness_dashboard.html#showAllRuns=true&tests=http%2Ftests%2Fcache%2Fdisk-cache%2Fdisk-cache-remove-several-pending-writes.html