tl;dr - web_tests will switch to running with threaded compositing by default.
A long-standing deficiency <https://bugs.chromium.org/p/chromium/issues/detail?id=770028> in the blink web_test framework is that content_shell runs with the blink compositor in single-threaded mode, which is not a configuration that we ship. We are working to remedy this, and as a first step we turned on threaded compositing by default <https://chromium-review.googlesource.com/c/chromium/src/+/4553625?tab=checks> for non-wpt web_tests on linux. We plan to expand this to all (web|wpt)_tests and to Mac/Windows trybots soon. This change shouldn't increase failures, flakiness, or test runtime, and should not increase the gardener's burden. There are ~100 tests that fail deterministically when threaded compositing is enabled, and a longer list (but less than 5% of all web_tests) that become flaky (or flakier). These tests have been added to a “quarantine list”, and will continue to run using the single-threaded compositor. In a later phase of this project, we will investigate specific failures and drive down the size of the quarantine list. By default, all new (web|wpt)_tests will run with threaded compositing. If you suspect a new test fails due to threaded compositing, please reach out to us. Yotam -- You received this message because you are subscribed to the Google Groups "blink-dev" group. To unsubscribe from this group and stop receiving emails from it, send an email to blink-dev+unsubscr...@chromium.org. To view this discussion on the web visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAB7U2GoLL3wECEJWQAp%2BV4CzeegQSzdJAUfKQhXsBR0o97809Q%40mail.gmail.com.
