On my El Capitan macbook I get a segfault when running the program below with more than a single process but only when MPICH has been compiled with Clang. I don't get that good debug info but here is some of what I got (lldb) c Process 61129 resuming Process 61129 stopped * thread #1: tid = 0x32c438, 0x00000003119d0432 libpmpi.12.dylib`MPID_Request_create + 244, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=EXC_I386_GPFLT) frame #0: 0x00000003119d0432 libpmpi.12.dylib`MPID_Request_create + 244 libpmpi.12.dylib`MPID_Request_create: -> 0x3119d0432 <+244>: movaps %xmm0, 0x230(%rax) 0x3119d0439 <+251>: movq $0x0, 0x240(%rax) 0x3119d0444 <+262>: movl %ecx, 0x210(%rax) 0x3119d044a <+268>: popq %rbp My version of Clang is Apple LLVM version 7.3.0 (clang-703.0.31) Target: x86_64-apple-darwin15.6.0 Thread model: posix InstalledDir: /Library/Developer/CommandLineTools/usr/bin and the bug has been confirmed by my colleague who is running Linux and compiling with Clang 3.8. The program runs fine with OpenMPI+Clang. #include <mpi.h> #include <stdio.h> #include <stdlib.h> int main(int argc, char *argv[]) { MPI_Init(&argc, &argv); MPI_Comm comm = MPI_COMM_WORLD; uint64_t *A, *C; int rnk; MPI_Comm_rank(comm, &rnk); A = calloc(1, sizeof(uint64_t)); C = calloc(2, sizeof(uint64_t)); A[0] = rnk + 1; MPI_Allgather(A, 1, MPI_UINT64_T, C, 1, MPI_UINT64_T, comm); MPI_Finalize(); return 0; } Best regards Andreas Noack Postdoctoral Associate Computer Science and Artificial Intelligence Laboratory Massachusetts Institute of Technology _______________________________________________ discuss mailing list [email protected] To manage subscription options or unsubscribe: https://lists.mpich.org/mailman/listinfo/discuss