[petsc-users] segfault in MatAssemblyEnd() when using large matrices on multi-core MAC OS-X

[Jed Brown]

On Mon, Jul 30, 2012 at 3:04 PM, Ronald M. Caplan <caplanr at predsci.com>wrote:

> I seem to have solved the problem.
>
> I was storing my entire matrix on node 0 and then calling MatAssembly
> (begin and end) on all nodes (which should have worked...).
>
> Apparently I was using too much space for the buffering or the like,
> because when I change the code so each node sets its own matrix values,
> than the MatAssemblyEnd does not seg fault.
>

Can you send the test case. It shouldn't seg-fault unless the machine runs
out of memory (and most desktop systems have overcommit, so the system will
kill arbitrary processes, not necessarily the job that did the latest
malloc.

In practice, you should call MatAssemblyBegin(...,MAT_FLUSH_ASSEMBLY)
periodically.


>
> Why should this be the case?   How many elements of a vector or matrix can
> a single node "set" before Assembly to distribute over all nodes?
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20120730/bc12a41c/attachment-0001.html>