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Subject: Re: [OMPI users] Sending relatively large messages with high frequency
From: Prentice Bisbal (prentice_at_[hidden])
Date: 2010-02-25 15:45:41

Amr Hassan wrote:
> Thanks alot for your reply,
> I'm using blocking Send and Receive. All the clients are sending data
> and the server is receive the messages from the clients with
> MPI_ANY_SOURCE as the sender. Do you think there is a race condition
> near this pattern?
> I searched a lot and used totalview but I couldn't detect such case. I
> really appreciate if you send me a link or give an example of a possible
> race condition in that scenario .
> Also, when I partition the message into smaller parts (send in sequence
> - all the other clients wait until the send finish) it works fine. is
> that exclude the race condition?

It sounds like, when sending the large messages, you are putting more
data into a buffer than it can hold. When you break the messages up into
 smaller sizes, you're not overflowing the buffer.

Are you using MPI_Pack, by any chance?

Prentice Bisbal
Linux Software Support Specialist/System Administrator
School of Natural Sciences
Institute for Advanced Study
Princeton, NJ