Re: WaitForMultipleObjects() Question

From:
"Scott McPhillips [MVP]" <org-dot-mvps-at-scottmcp>
Newsgroups:
microsoft.public.vc.mfc
Date:
Fri, 6 Nov 2009 08:56:54 -0500
Message-ID:
<e36KGkuXKHA.3676@TK2MSFTNGP05.phx.gbl>
"Ron H" <rnharsh@nospam.net> wrote in message
news:CLVIm.2988$ky1.1675@newsfe14.iad...

I have an app with several worker threads that deal with external hardware.
Each thread has several independent tasks that are triggered by an array of
events. I use CreateEvent() to define the events
withWaitForMultipleObjects() being the gate keeper. And of course event 0
is the shutdown task. At various points in the execution of the program, I
use SetEvent() to signal that I need one of the tasks to run. This is
pretty much straight out of Joe Newcomer's essays and it generally works
well. Once in a while an event is never acted upon and I believe that it is
because the thread gets bogged down and takes too long to complete a
task... ( just a guess)

Question: What is the life of an event? Is there a life timeout for a
signaled event? Is there a Queue for signaled events and if so how deep is
it?

Is there something I missed ( of course there is, but be gentle!)


I've built a few similar designs and have not seen such a problem. I
suspect you have a race or overlap condition. I.e., if you set an event that
is already set then only one event will be detected, not two. To avoid this
situation I generally prefer to make the threads message driven, since that
gives you a queue of signals to the thread.

--
Scott McPhillips [VC++ MVP]

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