305451 2026-01-13 21:39:11 -0800 [GTK][WPE][Coordinated Graphics] wheel event async scrolling doesn't work while the main thread is blocked 2026-01-28 23:06:03 -0800 1 1 1 Unclassified WebKit WebKitGTK WebKit Nightly Build Unspecified Unspecified RESOLVED FIXED P2 Normal --- 1 fujii webkit-unassigned bugs-noreply oldest_to_newest 2171673 0 fujii 2026-01-13 21:39:11 -0800 [GTK][WPE][Coordinated Graphics] wheel event async scrolling doesn't work while the main thread is blocked 1. Load the content 2. Send wheel events to scroll 3. Sometimes, the page doesn't start scrolling promptly This content repeats blocking the main thread for 2 seconds, and waiting for 1 second. If the wheel event is dispatched while the main thread is blocked, the async scrolling doesn't start until the block ends. 2171683 1 fujii 2026-01-13 22:35:53 -0800 Pull request: https://github.com/WebKit/WebKit/pull/56544 2171724 2 478006 fujii 2026-01-14 00:19:00 -0800 Created attachment 478006 scrollblock.html 2176093 3 ews-feeder 2026-01-28 23:05:59 -0800 Committed 306396@main (2f1345fa776a): <https://commits.webkit.org/306396@main> Reviewed commits have been landed. Closing PR #56544 and removing active labels. 478006 2026-01-14 00:19:00 -0800 2026-01-14 00:19:00 -0800 scrollblock.html scrollblock.html text/html 1221 fujii PGh0bWw+CjxoZWFkPgo8c2NyaXB0PgpmdW5jdGlvbiBibG9jaygpCnsKICAgIGNvbnNvbGUubG9n KCJCTE9DSyAtLSBzdGFydCIpOwogICAgdmFyIHN0YXJ0ID0gRGF0ZS5ub3coKTsKCiAgICB2YXIg aSA9IDA7CiAgICB3aGlsZSAodHJ1ZSkgewogICAgICAgIGZvciAodmFyIGkgPSAwOyBpIDwgMTAw MDAwMDsgKytpKQogICAgICAgICAgICBjb250aW51ZTsKCiAgICAgICAgdmFyIHRpbWUgPSBEYXRl Lm5vdygpOwogICAgICAgIGlmICh0aW1lIC0gc3RhcnQgPj0gMjAwMCkKICAgICAgICAgICAgYnJl YWs7CiAgICB9CgogICAgY29uc29sZS5sb2coIkJMT0NLIC0tIGVuZCIpOwogICAgc2V0VGltZW91 dChibG9jaywgMTAwMCk7Cn0KCnNldFRpbWVvdXQoYmxvY2ssIDEwMDApOwo8L3NjcmlwdD4KPHN0 eWxlPgojc2Nyb2xsYmxvY2sgewogICAgd2lkdGg6IDI1NnB4OwogICAgaGVpZ2h0OiAzMjc2OHB4 OwogICAgbWFyZ2luOiBhdXRvOwoKICAgIGJhY2tncm91bmQ6IGxpbmVhci1ncmFkaWVudCgKICAg ICAgICByZWQsIGdyZWVuLCBibHVlLCByZWQsIGdyZWVuLCBibHVlLCByZWQsIGdyZWVuLCBibHVl LCByZWQsIGdyZWVuLCBibHVlLAogICAgICAgIHJlZCwgZ3JlZW4sIGJsdWUsIHJlZCwgZ3JlZW4s IGJsdWUsIHJlZCwgZ3JlZW4sIGJsdWUsIHJlZCwgZ3JlZW4sIGJsdWUsCiAgICAgICAgcmVkLCBn cmVlbiwgYmx1ZSwgcmVkLCBncmVlbiwgYmx1ZSwgcmVkLCBncmVlbiwgYmx1ZSwgcmVkLCBncmVl biwgYmx1ZSwKICAgICAgICByZWQsIGdyZWVuLCBibHVlLCByZWQsIGdyZWVuLCBibHVlLCByZWQs IGdyZWVuLCBibHVlLCByZWQsIGdyZWVuLCBibHVlLAogICAgICAgIHJlZCwgZ3JlZW4sIGJsdWUs IHJlZCwgZ3JlZW4sIGJsdWUsIHJlZCwgZ3JlZW4sIGJsdWUsIHJlZCwgZ3JlZW4sIGJsdWUsCiAg ICAgICAgcmVkLCBncmVlbiwgYmx1ZSwgcmVkLCBncmVlbiwgYmx1ZSwgcmVkLCBncmVlbiwgYmx1 ZSwgcmVkLCBncmVlbiwgYmx1ZSwKICAgICAgICByZWQsIGdyZWVuLCBibHVlLCByZWQsIGdyZWVu LCBibHVlLCByZWQsIGdyZWVuLCBibHVlLCByZWQsIGdyZWVuLCBibHVlLAogICAgICAgIHJlZCwg Z3JlZW4sIGJsdWUsIHJlZCwgZ3JlZW4sIGJsdWUsIHJlZCwgZ3JlZW4sIGJsdWUsIHJlZCwgZ3Jl ZW4sIGJsdWUpOwp9Cjwvc3R5bGU+CjwvaGVhZD4KPGJvZHk+CjxkaXYgaWQ9InNjcm9sbGJsb2Nr Ij48L2Rpdj4KPC9ib2R5Pgo8aHRtbD4K