Dave et al., I am still conversing with the application developer about this issue. It looks like I jumped to the wrong conclusion based on the mpiP data that I collected. I won't ask you to read this whole, post. But if you can read the last post by fgygi here: http://fpmd.ucdavis.edu/qbox-list/viewtopic.php?f=3&t=219&start=10 I have asked him to try to create a reduced test case based on MPI only. The code is written on top of ScaLAPACK, there is a for loop that creates a communicator, then destroy it based on its rank on the 2D processor grid. Ultimately, when the loop is over, MPI_Comm_create/Comm_free can be called about 1000 times, but only one of those communicators will continue existing. ----- Original Message -----
From: "Nichols A. Romero" <[email protected]> To: [email protected] Sent: Monday, February 25, 2013 2:17:04 PM Subject: Re: [mpich-discuss] Maximum number of communicators
I cannot reproduce this in a simple test code. I am convinced that this is an application error. I linked the application against mpiP and I see that the calls to Comm_create >> Comm_free by two to three orders of magnitude.
The application is template C++ and I suspect that the C++ class destructor is not properly calling Comm_free.
----- Original Message -----
From: "Dave Goodell" <[email protected]> To: [email protected] Sent: Sunday, February 24, 2013 3:36:54 PM Subject: Re: [mpich-discuss] Maximum number of communicators
Test code indeed would be helpful.
You may get better warnings about context ID and/or communicator leaks if you configure a stock MPICH with "--enable-g=all".
-Dave
On Feb 23, 2013, at 7:05 PM CST, Jeff Hammond wrote:
It's 2048 in all MPICH2-derived implementations that I know about, including the ones used on BGP and BGQ.
Since I know what your issue is already, I think the problem has something to do with context id leaking. You should post your test code.
Jeff
On Sat, Feb 23, 2013 at 6:24 PM, Nichols A. Romero <[email protected]> wrote:
Hi,
What is the maximum number of communicators in the MPICH that is used on BG/P vs. that used on BG/Q?
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-- Nichols A. Romero, Ph.D. Argonne Leadership Computing Facility Argonne National Laboratory Building 240 Room 2-127 9700 South Cass Avenue Argonne, IL 60490 (630) 252-3441