There is no real reason why we can't support recording multiple canvases at the same time. The backend is able to handle it without any issue.
Created attachment 351661 [details]
Comment on attachment 351661 [details]
Is it possible to add a test case that starts multiple canvas recordings, triggers frames then waits for all to be stopped?
Created attachment 351822 [details]
Comment on attachment 351822 [details]
Clearing flags on attachment: 351822
Committed r236952: <https://trac.webkit.org/changeset/236952>
All reviewed patches have been landed. Closing bug.
It looks like https://trac.webkit.org/changeset/236952/webkit
Has caused the test inspector/canvas/shaderProgram-add-remove-webgl.html
to time out constantly.