Hi Folks, I am using MatZeroRows() to set Dirichlet boundary conditions. This works fine for the serial run and the solver produces correct results (verified through analytical solution). However, when I run the case in parallel, the simulation gets stuck at MatZeroRows(). My understanding is that this function needs to be called after the MatAssemblyBegin{End}() has been called, and should be called by all processors. Here is that bit of the code which calls MatZeroRows() after the matrix has been assembled
https://github.com/IBAMR/IBAMR/blob/amneetb/acoustically-driven-flows/src/acoustic_streaming/AcousticStreamingPETScMatUtilities.cpp#L724-L801 I ran the parallel code (on 3 processors) in the debugger (-start_in_debugger). Below is the call stack from the processor that gets stuck amneetb@APSB-MBP-16:~$ lldb -p 4307 (lldb) process attach --pid 4307 Process 4307 stopped * thread #1, queue = 'com.apple.main-thread', stop reason = signal SIGSTOP frame #0: 0x000000018a2d750c libsystem_kernel.dylib`__semwait_signal + 8 libsystem_kernel.dylib`: -> 0x18a2d750c <+8>: b.lo 0x18a2d752c ; <+40> 0x18a2d7510 <+12>: pacibsp 0x18a2d7514 <+16>: stp x29, x30, [sp, #-0x10]! 0x18a2d7518 <+20>: mov x29, sp Target 0: (fo_acoustic_streaming_solver_2d) stopped. Executable module set to "/Users/amneetb/Softwares/IBAMR-Git/objs-dbg/tests/IBTK/fo_acoustic_streaming_solver_2d". Architecture set to: arm64-apple-macosx-. (lldb) cont Process 4307 resuming Process 4307 stopped * thread #1, queue = 'com.apple.main-thread', stop reason = signal SIGSTOP frame #0: 0x0000000109d281b8 libpmpi.12.dylib`MPIDI_POSIX_mpi_barrier_release_gather + 400 libpmpi.12.dylib`MPIDI_POSIX_mpi_barrier_release_gather: -> 0x109d281b8 <+400>: ldr w9, [x24] 0x109d281bc <+404>: cmp w8, w9 0x109d281c0 <+408>: b.lt 0x109d281a0 ; <+376> 0x109d281c4 <+412>: bl 0x109d28e64 ; MPID_Progress_test Target 0: (fo_acoustic_streaming_solver_2d) stopped. (lldb) bt * thread #1, queue = 'com.apple.main-thread', stop reason = signal SIGSTOP * frame #0: 0x0000000109d281b8 libpmpi.12.dylib`MPIDI_POSIX_mpi_barrier_release_gather + 400 frame #1: 0x0000000109d27d14 libpmpi.12.dylib`MPIDI_SHM_mpi_barrier + 224 frame #2: 0x0000000109d27b60 libpmpi.12.dylib`MPIDI_Barrier_intra_composition_alpha + 44 frame #3: 0x0000000109d0d490 libpmpi.12.dylib`MPIR_Barrier + 900 frame #4: 0x000000010224d030 libmpi.12.dylib`MPI_Barrier + 684 frame #5: 0x00000001045ea638 libpetsc.3.17.dylib`PetscCommDuplicate(comm_in=-2080374782, comm_out=0x000000010300bcb0, first_tag=0x000000010300bce4) at tagm.c:235:5 frame #6: 0x00000001045f2910 libpetsc.3.17.dylib`PetscHeaderCreate_Private(h=0x000000010300bc70, classid=1211227, class_name="PetscSF", descr="Star Forest", mansec="PetscSF", comm=-2080374782, destroy=(libpetsc.3.17.dylib`PetscSFDestroy at sf.c:224), view=(libpetsc.3.17.dylib`PetscSFView at sf.c:841)) at inherit.c:62:3 frame #7: 0x00000001049cf820 libpetsc.3.17.dylib`PetscSFCreate(comm=-2080374782, sf=0x000000016f911a50) at sf.c:62:3 frame #8: 0x0000000104cd3024 libpetsc.3.17.dylib`MatZeroRowsMapLocal_Private(A=0x00000001170c1270, N=1, rows=0x000000016f912cb4, nr=0x000000016f911df8, olrows=0x000000016f911e00) at zerorows.c:36:5 frame #9: 0x000000010504ea50 libpetsc.3.17.dylib`MatZeroRows_MPIAIJ(A=0x00000001170c1270, N=1, rows=0x000000016f912cb4, diag=1, x=0x0000000000000000, b=0x0000000000000000) at mpiaij.c:768:3 frame #10: 0x0000000104d95fac libpetsc.3.17.dylib`MatZeroRows(mat=0x00000001170c1270, numRows=1, rows=0x000000016f912cb4, diag=1, x=0x0000000000000000, b=0x0000000000000000) at matrix.c:5935:3 frame #11: 0x000000010067d320 fo_acoustic_streaming_solver_2d`IBAMR::AcousticStreamingPETScMatUtilities::constructPatchLevelFOAcousticStreamingOp(mat=0x000000016f91c178, omega=1, sound_speed=1, rho_idx=3, mu_idx=2, lambda_idx=4, u_bc_coefs=0x000000016f91c3a8, data_time=NaN, num_dofs_per_proc=size=3, u_dof_index_idx=27, p_dof_index_idx=28, patch_level=Pointer<SAMRAI::hier::PatchLevel<2> > @ 0x000000016f914ed0, mu_interp_type=VC_HARMONIC_INTERP) at AcousticStreamingPETScMatUtilities.cpp :794:36 frame #12: 0x0000000100694bdc fo_acoustic_streaming_solver_2d`IBAMR::FOAcousticStreamingPETScLevelSolver::initializeSolverStateSpecialized(this=0x000000016f91c028, x=0x000000016f91d788, (null)=0x000000016f91d690) at FOAcousticStreamingPETScLevelSolver.cpp:149:5 frame #13: 0x000000010083232c fo_acoustic_streaming_solver_2d`IBTK::PETScLevelSolver::initializeSolverState(this=0x000000016f91c028, x=0x000000016f91d788, b=0x000000016f91d690) at PETScLevelSolver.cpp:340:5 frame #14: 0x00000001004eb230 fo_acoustic_streaming_solver_2d`main(argc=11, argv=0x000000016f91f460) at fo_acoustic_streaming_solver.cpp:400:22 frame #15: 0x0000000189fbbf28 dyld`start + 2236 Any suggestions on how to avoid this barrier? Here are all MAT options I am using (in the debug mode), if that is helpful: https://github.com/IBAMR/IBAMR/blob/amneetb/acoustically-driven-flows/src/acoustic_streaming/AcousticStreamingPETScMatUtilities.cpp#L453-L458 Thanks, -- --Amneet