[Beowulf] MPICH2: Handle Limit?
rhamann at uccs.edu
Fri Feb 4 11:31:01 PST 2005
I thought any limit would be wierd, let alone something like 84 (7 X
12?) Anyway, I thought it was based on the number of MPI variables
declared (data_types, windows, requests) because every time I added
new declarations, it would hang on Fedora core 2, but run to
completion on Scyld (but with erroneous results). If I deleted unused
MPI declarations, it would start to work again. I counted all my
handles and came up with 84.
However, after deleting two 26 element arrays of handles, I thought it
would work. When I added more handles, it bombed again. I started to
try other things. I added 4 junk ints. I didn't use the variables I
declared, but it still bombed. When I converted them to chars, it
started working again. Very strange.
Have you ever encountered this before? I'm doing a 3d cellular
automata, so I need a lot of datatypes for exchange of ghost cells.
It's obviously some strange error I've made that's manifesting itself
in MPI instead of a runtime or sytax error. I'm gonna try looking for
any buffer overruns now, but other than that I'm stumped.
GCC on Fedora Core 2 and on Scyld Beowulf
MPICH 2 1.0
On Fri, 4 Feb 2005 12:16:17 -0600 (CST)
Rob Ross <rross at mcs.anl.gov> wrote:
> Hi Ron,
> There should not be an 84 handle limit.
> Can you tell me what version of MPICH2 this is, and what
> OS you're running on? Do you have a simple test that exhibits the
> Rob Ross, Mathematics and Computer Science Division, Argonne
> On Thu, 3 Feb 2005, R Hamann wrote:
>> I've been having some strange problems with a program using the
>> library. When I added some new datatypes for ghost cell exchange,
>> program would hang. I figured out that any number of handles over
>> would cause this. Fortunately, I could delete some handles that I
>> longer needed, but it still seemed strange. Are my calculations
>> correct that for each process there is an 84 handle limit? or am I
>> seeing some other problem?
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