Inter-Thread Communication

Daniel Kanev

How can I send messages from one thread to another? I want to avoid busy/wait loops. Thank you.

CPallini

If a thread has a message queue (for instance GUI threads have it) then you know how to do it. As for worker threads this page [^] may help. :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
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killabyte

I would use pipes http://msdn.microsoft.com/en-us/library/aa365781(VS.85).aspx[^]

Cedric Moonen

As a remark, it's also usefull to know that you can access the variables directly (providing you have a way to access them) from within the different threads.

Cédric Moonen Software developer
Charting control [v1.4] OpenGL game tutorial in C++ [New]

killabyte

wow 2 votes of 1 .... i guess i fail ;P any reason why this isn't a good messaging scheme?

Iain Clarke Warrior Programmer

I've only just seen your post, so I'm not one of the 2 1's, but pipes are a heavy duty solution that's too cumbersome most of the time. I've used them myself between processes - the idea was that one of my processes might not even be on the same PC, so they give good flexibility. But between two threads in the same the same process, I think they're over the top. Especially for worker->ui thread communications. PostMessage works a treat, and fits nicely into the MFC message loop handling. For pipes, you'd need to alter the message pump to wait for events (you have overlapped I/O I hope!) and messages. For ui->worker thread communications, pipes are more appropriate - especially if it's opened in message mode. Iain.

Plz sir... CPallini CPallini abuz drugz, plz plz help urgent.

killabyte

Hmm u raise a good point, PostMessage() or PostThreadMessage() probably more applicable in this case. thinking back to when i have used pipes i have been shooting off messages then a chunk of data. i will admit i like pulling out the nail gun even if i only have to put in one nail :-\