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<div dir="ltr">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"
<div>After attaching gdb to one process, you can use bt to see its stack trace.<br>
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<div dir="ltr">--Junchao Zhang</div>
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<div dir="ltr" class="gmail_attr">On Sat, Sep 28, 2019 at 5:33 AM Michael Wick <<a href="mailto:michael.wick.1980@gmail.com">michael.wick.1980@gmail.com</a>> wrote:<br>
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<div>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.</div>
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<div>Do you have any suggestions to do?<br>
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<div dir="ltr" class="gmail_attr">On Fri, Sep 27, 2019 at 8:17 PM Zhang, Junchao <<a href="mailto:jczhang@mcs.anl.gov" target="_blank">jczhang@mcs.anl.gov</a>> wrote:<br>
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<div dir="ltr">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.
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<div dir="ltr">--Junchao Zhang</div>
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<div dir="ltr" class="gmail_attr">On Fri, Sep 27, 2019 at 4:24 PM Michael Wick via petsc-maint <<a href="mailto:petsc-maint@mcs.anl.gov" target="_blank">petsc-maint@mcs.anl.gov</a>> wrote:<br>
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<div>Hi PETSc:</div>
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<div>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.</div>
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<div>I have used valgrind and detect nothing. I just wonder if you have any suggestions.</div>
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<div>Thanks!!!</div>
<div>M<br>
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