[FLASH-BUGS] MPI_REQUEST_MAX

[Rusty Lusk]

You should not need to call MPI_Request_free if your Isend's and Irecv's
are waited on with MPI_Wait or MPI_Waitall.  So it is not an obviously
bad thing if there are no explicit calls to MPI_Request_Free.  But
something is causing you to have lots of requests active at one time.
16,000 is pretty many for a single process.

Rusty Lusk

From: Peter Woitke <woitke at strw.leidenuniv.nl>
Subject: [FLASH-BUGS] MPI_REQUEST_MAX
Date: Thu, 2 Dec 2004 14:14:47 +0100 (MET)

> Dear developers,
> 
> for long runs (more than 12 hours on 32 Processors) my flash-job
> crashes with error message
> 
> *** MPI has run out of request entries.
> *** The current allocation level is:
> ***     MPI_REQUEST_MAX = 16384
> 
> Here is some advice from google:
> http://www.cray.com/craydoc/manuals/004-3687-001/html-004-3687-001/zfixe
> dlqtgeczn.htmlD
> 8.5. Why do I keep getting error messages about MPI_REQUEST_MAX being
> too small, no matter how large I set it?
> You are probably calling MPI_Isend(3) or MPI_Irecv(3) and not completing
> or freeing your request objects. You should use MPI_Request_free(3), as
> described in the previous question.
> 
> I checked that, indeed, MPI_Isend and MPI_Irecv are called from the 
> FLASH-code, but MPI_Request_free is never called.
> 
> Have you thought about this?
> 
> Thanx,
> 
> Peter Woitke
>