1267368 - Initialize the content process main thread to the COM multithreaded apartment

Status: RESOLVED INVALID

(Core :: DOM: Content Processes, defect)

Description

[(No longer employed by Mozilla) Aaron Klotz]

Since the content process does not directly call Windows GUI APIs, we should initialize its main thread to the multithreaded apartment. This offers significant performance and stability benefits due since we can avoid marshaling inter-thread method invocations through the Windows message pump.

This is also required for a11y+e10s to successfully hand off method invocations from the RPC thread pool to the content process main thread.


I do see some gfx code that is initializing on the STA. I'll discuss with gfx to find out what the true requirements are... in my experience a lot of code just does STA because somebody needed COM, didn't know how apartments worked, but also didn't care as long as it worked. :-)

Comment 1

[(No longer employed by Mozilla) Aaron Klotz]

Attachment: Proposed patch

This only #ifdefs on XP_WIN, not on a11y. My reasoning for this is that if we're going to switch to MTA on the main thread, that should be enforced across all configurations so that we don't end up unexpectedly confusing people.

Comment 2

[(No longer employed by Mozilla) Aaron Klotz]

It turns out that ICallFrame objects are okay to handoff between apartments, so we're okay here.