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] Patch
Comment on attachment 351661 [details] Patch r=me 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] Patch
Comment on attachment 351822 [details] Patch Clearing flags on attachment: 351822 Committed r236952: <https://trac.webkit.org/changeset/236952>
All reviewed patches have been landed. Closing bug.
<rdar://problem/45111502>
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. History: https://webkit-test-results.webkit.org/dashboards/flakiness_dashboard.html#showAllRuns=true&tests=inspector%2Fcanvas%2FshaderProgram-add-remove-webgl.html