Joachim, Unfortunately, using MPI_Improbe/MPI_Mrecv didn't solve the problem -- I still am receiving buffers with invalid data objects near the ends of the buffers. The problem goes away when I reduce the size of the job (number of nodes), making me think it is the large number of messages that is causing the problem. 1. Is there a way to detect this kind of overload with an MPI call? 2. Is there an upper bound on the number of messages that can be "in flight"? 3. Is there a upper bound on message length? Or is there some other possible cause that I haven't thought of? Thanks, Kurt -----Original Message----- From: Joachim Jenke via discuss <[email protected]> Sent: Thursday, September 14, 2023 3:10 PM To: [email protected] Cc: Joachim Jenke <[email protected]> Subject: [EXTERNAL] [BULK] Re: [mpich-discuss] Buffer corruption due to an excessive number of messages CAUTION: This email originated from outside of NASA. Please take care when clicking links or opening attachments. Use the "Report Message" button to report suspicious messages to the NASA SOC. Hi Kurt, just a thought: do you execute single-threaded or multi-threaded? In case of multi-threaded execution, you should look into MPI_Improbe/MPI_Mrecv just to make sure that you really receive the message you probed for. Even in single-threaded execution you might try whether using these functions instead fixes your issue. Best Joachim Am 14.09.23 um 22:02 schrieb Mccall, Kurt E. (MSFC-EV41) via discuss:

It seems that when I send a process too many non-blocking messages (with MPI_Isend) , MPI_Iprobe/MPI_Recv sometimes returns a buffer

with corrupted data for some of the messages. Usually the corrupted data objects are at the end of the array that was sent. I checked the

buffers passed to MPI_Isend, and they are uncorrupted.

1. Is there a way to detect this kind of overload with an MPI call? 2. Is there an upper bound on the number of messages that can be "in flight"? 3. Is there a upper bound on message length?

Thanks,

Kurt

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