Re: dll loading time performance

From:

"Ben Voigt [C++ MVP]" <rbv@nospam.nospam>

Newsgroups:

microsoft.public.vc.language

Date:

Tue, 19 Feb 2008 09:08:14 -0600

Message-ID:

<#Suo$jwcIHA.2000@TK2MSFTNGP05.phx.gbl>

Tim Roberts wrote:

Frank-O <franck.nasse.oxinus@gmail.com> wrote:

I'll give you one example. What if that DLL is creating GUI
elements, like windows? Windows receive messages on the queue of
the thread that created them.

Could you explain your statement ?

When you call CreateWindow, that window is "owned" by the thread that
created it, and messages for that window will be sent into the message
queue for that thread. The normal message loop, which runs in the
main thread, will never see them. In fact, if that second thread
doesn't start a message loop, the messages will never be processed.

Of course, since you are starting the second thread yourself and managing
the DLL load, running a message dispatch loop there is entirely possible.

That's why you read so many articles warning about combining GUI
operations with multithreading.

Now, if you know the DLL isn't going to create any windows, then it
would be fine to call it from a second thread. I just presented one
possible counterexample.