Hey George, thanks of course, this fully explains it, I simply assumed it being a problem of the child process. In this case there is also no issue with negative values when considering the modulo 256.
BR Alex From: George Bosilca <bosi...@icl.utk.edu> Sent: Wednesday, July 19, 2023 4:45 PM To: Alexander Stadik <alexander.sta...@essteyr.com> Cc: Open MPI Users <users@lists.open-mpi.org> Subject: [EXT] Re: [EXT] Re: [OMPI users] Error handling External: Check sender address and use caution opening links or attachments Alex, exit(status) does not make status available to the parent process wait, instead it makes the low 8 bits available to the parent as unsigned. This explains why small positive values seem to work correctly while negative values do not (because of the 32 bits negative value representation in complement to two). George. On Wed, Jul 19, 2023 at 12:45 AM Alexander Stadik <alexander.sta...@essteyr.com<mailto:alexander.sta...@essteyr.com>> wrote: Hey George, I said random only because I do not see the method behind it, but exactly like this when I do allreduce by MIN and return a negative number I get either 248, 253, 11 or 6 usually. Meaning that's purely a number from MPI side. The Problem with MPI_Abort is it shows the correct number in its output in Logfile, but it does not communicate its value to other processes, or forward its value to exit. So one also always sees these "random" values. When using positive numbers in range it seems to work, so my question was on how it works, and how one can do it? Is there a way to let MPI_Abort communicate the value as exit code? Why do negative numbers not work, or does one simply have to always use positive numbers? Why I would prefer Abort is because it seems safer. BR Alex ________________________________ Von: George Bosilca <bosi...@icl.utk.edu<mailto:bosi...@icl.utk.edu>> Gesendet: Dienstag, 18. Juli 2023 18:47 An: Open MPI Users <users@lists.open-mpi.org<mailto:users@lists.open-mpi.org>> Cc: Alexander Stadik <alexander.sta...@essteyr.com<mailto:alexander.sta...@essteyr.com>> Betreff: [EXT] Re: [OMPI users] Error handling External: Check sender address and use caution opening links or attachments Alex, How are your values "random" if you provide correct values ? Even for negative values you could use MIN to pick one value and return it. What is the problem with `MPI_Abort` ? it does seem to do what you want. George. On Tue, Jul 18, 2023 at 4:38 AM Alexander Stadik via users <users@lists.open-mpi.org<mailto:users@lists.open-mpi.org>> wrote: Hey everyone, I am working for longer time now with cuda-aware OpenMPI, and developed longer time back a small exceptions handling framework including MPI and CUDA exceptions. Currently I am using MPI_Abort with costum error numbers, to terminate everything elegantly, which works well, by just reading the logfile in case of a crash. Now I was wondering how one can handle return / exit codes properly between processes, since we would like to filter non-zero exits by return code. One way is a simple Allreduce (in my case) + exit instead of Abort. But the problem seems to be the values are always "random" (since I was using negative codes), only by using MPI error codes it seems to work correctly. But usage of that is limited. Any suggestions on how to do this / how it can work properly? 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