[petsc-users] [petsc-maint] petsc ksp solver hangs

[Michael Wick]

Thank you all for the reply.

I am trying to get the backtrace. However, the code hangs totally randomly,
and it hangs only when I run large simulations (e.g. 72 CPUs for this one).
I am trying very hard to get the error message.

So far, I can pin-point that the issue is related with hypre, and a static
build of the petsc library. Switching to a dynamic build works fine so far.
Also, using a naked gmres works. Does anyone have similar issues before?

On Sat, Sep 28, 2019 at 6:28 AM Stefano Zampini <stefano.zampini at gmail.com>
wrote:

> In my experience, an hanging execution may results from seterrq being
> called with the wrong communicator. Anyway, it would be useful to get the
> output of -log_trace .
>
> Also, does it hang when -pc_type none is specified?
>
> Il Sab 28 Set 2019, 16:22 Zhang, Junchao via petsc-users <
> petsc-users at mcs.anl.gov> ha scritto:
>
>> Does it hang with  2 or 4 processes? Which PETSc version do you use
>> (using the latest is easier for us to debug)?  Did you configure PETSc with
>> --with-debugging=yes COPTFLAGS="-O0 -g"  CXXOPTFLAGS="-O0 -g"
>> After attaching gdb to one process, you can use bt  to see its stack
>> trace.
>>
>> --Junchao Zhang
>>
>>
>> On Sat, Sep 28, 2019 at 5:33 AM Michael Wick <michael.wick.1980 at gmail.com>
>> wrote:
>>
>>> I attached a debugger to my run. The code just hangs without throwing an
>>> error message, interestingly. I uses 72 processors. I turned on the ksp
>>> monitor. And I can see it hangs either at the beginning or the end of KSP
>>> iteration. I also uses valgrind to debug my code on my local machine, which
>>> does not detect any issue. I uses fgmres + fieldsplit, which is really a
>>> standard option.
>>>
>>> Do you have any suggestions to do?
>>>
>>> On Fri, Sep 27, 2019 at 8:17 PM Zhang, Junchao <jczhang at mcs.anl.gov>
>>> wrote:
>>>
>>>> How many MPI ranks did you use? If it is done on your desktop, you can
>>>> just attach a debugger to a MPI process to see what is going on.
>>>>
>>>> --Junchao Zhang
>>>>
>>>>
>>>> On Fri, Sep 27, 2019 at 4:24 PM Michael Wick via petsc-maint <
>>>> petsc-maint at mcs.anl.gov> wrote:
>>>>
>>>>> Hi PETSc:
>>>>>
>>>>> I have been experiencing a code stagnation at certain KSP iterations.
>>>>> This happens rather randomly, which means the code may stop at the middle
>>>>> of a KSP solve and hangs there.
>>>>>
>>>>> I have used valgrind and detect nothing. I just wonder if you have any
>>>>> suggestions.
>>>>>
>>>>> Thanks!!!
>>>>> M
>>>>>
>>>>
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