[petsc-users] Error with MatSchurComplement

[Griffith, Boyce Eugene]

> On Feb 17, 2016, at 12:57 AM, Barry Smith <bsmith at mcs.anl.gov> wrote:
> 
> 
>  Hmm, it seems this should never happen. It is like inconsistent (and in correct) IS are being generated. 
> 
>   1 is an odd number of processes, does it happen then?
> 
>   Are you providing the IS yourself to the PCFIELDSPLIT or using the default? If you are providing them is it possible that you have a bug in generating them for certain configurations? Of course it could also be a bug in PETSc. 

We are doing this ourselves.  Could this happen if we accidentally duplicated entries in one of the IS'es on different processors?

-- Boyce

>   I recommend trying to produce the crash on a small a problem as possible then run in the debugger to check the IS at each stage to see why one of them becomes bonkers.
> 
>   It could be we should have more asserts in PETSc to insure that input IS are compatible.
> 
>  Barry
> 
>> On Feb 16, 2016, at 10:37 PM, Bhalla, Amneet Pal S <amneetb at live.unc.edu> wrote:
>> 
>> Hi Folks,
>> 
>> I am getting error with odd number of processors with PCFIELDSPLIT. The error log is attached. Any hints where to start digging?
>> 
>> 
>> +++++++++++++++++++++++++++++++++++++++++++++++++++
>> At beginning of timestep # 0
>> Simulation time is 0
>>    Residual norms for ib_ solve.
>>    0 KSP unpreconditioned resid norm 5.093934451651e+05 true resid norm 5.093934451651e+05 ||r(i)||/||b|| 1.000000000000e+00
>> [2]PETSC ERROR: --------------------- Error Message --------------------------------------------------------------
>> [2]PETSC ERROR: Nonconforming object sizes
>> [2]PETSC ERROR: Local columns of A10 1072 do not equal local rows of A00 1104
>> [2]PETSC ERROR: See http://www.mcs.anl.gov/petsc/documentation/faq.html for trouble shooting.
>> [2]PETSC ERROR: Petsc Release Version 3.6.1, unknown 
>> [2]PETSC ERROR: ./main2d on a darwin-dbg named Amneets-MBP.attlocal.net by Taylor Tue Feb 16 20:30:45 2016
>> [2]PETSC ERROR: Configure options --CC=mpicc --CXX=mpicxx --FC=mpif90 --PETSC_ARCH=darwin-dbg --with-debugging=1 --with-c++-support=1 --with-hypre=1 --download-hypre=1 --with-hdf5=yes --with-hdf5-dir=/Users/Taylor/Documents/SOFTWARES/HDF5/
>> [2]PETSC ERROR: #1 MatSchurComplementSetSubMatrices() line 261 in /Users/Taylor/Documents/SOFTWARES/PETSc-BitBucket/PETSc/src/ksp/ksp/utils/schurm.c
>> [2]PETSC ERROR: #2 PCSetUp_FieldSplit() line 714 in /Users/Taylor/Documents/SOFTWARES/PETSc-BitBucket/PETSc/src/ksp/pc/impls/fieldsplit/fieldsplit.c
>> [2]PETSC ERROR: #3 PCSetUp() line 983 in /Users/Taylor/Documents/SOFTWARES/PETSc-BitBucket/PETSc/src/ksp/pc/interface/precon.c
>> [2]PETSC ERROR: #4 KSPSetUp() line 332 in /Users/Taylor/Documents/SOFTWARES/PETSc-BitBucket/PETSc/src/ksp/ksp/interface/itfunc.c
>> [2]PETSC ERROR: #5 KSPSolve() line 546 in /Users/Taylor/Documents/SOFTWARES/PETSc-BitBucket/PETSc/src/ksp/ksp/interface/itfunc.c
>> [2]PETSC ERROR: #6 solveSystem() line 229 in ../../../IBAMR/ibtk/lib/../src/solvers/impls/PETScLevelSolver.cpp
>> P=00002:Program abort called in file ``../../../IBAMR/ibtk/lib/../src/solvers/impls/PETScLevelSolver.cpp'' at line 229
>> P=00002:ERROR MESSAGE: 
>> P=00002:
>> application called MPI_Abort(MPI_COMM_WORLD, -1) - process 2
>> *** Warning, AutoPtr is deprecated and will be removed in a future library version! ./include/libmesh/auto_ptr.h, line 271, compiled Feb  3 2016 at 10:29:17 ***
>> 
>> 
>> — Amneet 
>> 
>>