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.1...@gmail.com<mailto:michael.wick.1...@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 <jczh...@mcs.anl.gov<mailto:jczh...@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-ma...@mcs.anl.gov<mailto:petsc-ma...@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
