[webkit-reviews] review requested: [Bug 72155] Replace Qt QThread threading back-end with pthread/Win32 threading back-ends : [Attachment 116639] initialize webkit_main_thread_invoker() on main thread

[bugzilla-daemon at webkit.org]

Andrew Wason <rectalogic at rectalogic.com> has asked  for review:
Bug 72155: Replace Qt QThread threading back-end with pthread/Win32 threading
back-ends
https://bugs.webkit.org/show_bug.cgi?id=72155

Attachment 116639: initialize webkit_main_thread_invoker() on main thread
https://bugs.webkit.org/attachment.cgi?id=116639&action=review

------- Additional Comments from Andrew Wason <rectalogic at rectalogic.com>
Updated the patch to initialize webkit_main_thread_invoker() on the main
thread. The recent changes to dispatchFunctionsFromMainThread() from bug 72704
prevent the native threads from being infected by QAdoptedThread - but we need
to only create webkit_main_thread_invoker() on the main thread or else the
thread it is first created on becomes a QAdoptedThread leading to problems
discussed in bug 72538.

So I believe this patch now also fixes bug 72538 - i.e. Qt no longer needs to
wait for worker threads to exit when shutting down since the workers are plain
native threads.

However, my test application still crashes occasionally - but not necessarily
during shutdown. I was able to reproduce the crash in a test app that never
shuts down (just periodically reloads a QWebPage with workers) - so I think
that is a different bug.

So I think we should proceed with applying this patch, assuming it passes
review, and then I'll close bug 72538 and open a new bug for this new worker
crash issue.