Re: How does COM pick a thread to create object in?

From:
"Igor Tandetnik" <itandetnik@mvps.org>
Newsgroups:
microsoft.public.vc.atl
Date:
Tue, 25 Sep 2007 15:59:22 -0400
Message-ID:
<#L5ES66$HHA.4324@TK2MSFTNGP02.phx.gbl>
Scott McPhillips [MVP] <org-dot-mvps-at-scottmcp> wrote:

"Igor Tandetnik" <itandetnik@mvps.org> wrote in message
news:eCtE%23p5$HHA.1204@TK2MSFTNGP03.phx.gbl...

Scott McPhillips [MVP] <org-dot-mvps-at-scottmcp> wrote:

I would like to create a bunch of identical objects in my server
from my client, with each one in a thread of its own.


See CComAutoThreadModule, DECLARE_CLASSFACTORY_AUTO_THREAD

Using STA,
obviously COM picks a thread somehow, but what determines which
thread it picks?


Are we talking about in-proc or out-of-proc server? See also

http://support.microsoft.com/support/kb/articles/q150/7/77.asp


This is for an out-of-proc server.


Your server calls CoRegisterClassObject on a particular thread, to
register its class factory. When the client creates the object, COM is
going to call IClassFactory::CreateInstance on this same thread.
Normally, the class factory would just create a new instance on the same
thread again, but of course nothing prevents one from writing a class
factory that spins a new thread for each object it creates. You can
study the source code for CComClassFactoryAutoThread and related
classes - they do something similar.
--
With best wishes,
    Igor Tandetnik

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