Start by saying that I have not been involved in the nitty gritty of the per-object locking design. What protects the attached buffer/data structures/request when doing multithreaded MPI_Bsend()'s? All I see in the code path is a (no-op) MPIU_THREAD_CS_ENTER(ALLFUNC,). I have a customer test in which the threads seem to be walking all over the request around: /bgusr/bobc/bgq/comm/lib/dev/mpich2/src/mpid/pamid/include/../src/mpid_request.h:259 0000000001088c0c MPIR_Request_complete /bgusr/bobc/bgq/comm/lib/dev/mpich2/src/mpi/pt2pt/mpir_request.c:87 000000000106e874 MPIR_Test_impl /bgusr/bobc/bgq/comm/lib/dev/mpich2/src/mpi/pt2pt/test.c:62 00000000010188f0 MPIR_Bsend_check_active /bgusr/bobc/bgq/comm/lib/dev/mpich2/src/mpi/pt2pt/bsendutil.c:455 0000000001018dc0 MPIR_Bsend_isend /bgusr/bobc/bgq/comm/lib/dev/mpich2/src/mpi/pt2pt/bsendutil.c:226 0000000001008734 PMPI_Bsend /bgusr/bobc/bgq/comm/lib/dev/mpich2/src/mpi/pt2pt/bsend.c:163 00000000010009c0 00000012.long_branch_r2off.__libc_start_main+0 :0 000000000130cbc0 start_thread eg. (fprinting from MPIU_HANDLE_LOG_REFCOUNT_CHANGE) stderr[8]: set 0x15f8048 (0xac0000ff kind=REQUEST) refcount to 2 stderr[8]: decr 0x15f8048 (0xac0000ff kind=REQUEST) refcount to 1 stderr[8]: decr 0x15f8048 (0xac0000ff kind=REQUEST) refcount to 0 stderr[8]: decr 0x15f8048 (0xac0000ff kind=REQUEST) refcount to -1 stderr[8]: decr 0x15f8048 (0xac0000ff kind=REQUEST) refcount to -2 stderr[8]: decr 0x15f8048 (0xac0000ff kind=REQUEST) refcount to -3 stderr[8]: decr 0x15f8048 (0xac0000ff kind=REQUEST) refcount to -4 stderr[8]: decr 0x15f8048 (0xac0000ff kind=REQUEST) refcount to -5 stderr[8]: decr 0x15f8048 (0xac0000ff kind=REQUEST) refcount to -6 stderr[8]: decr 0x15f8048 (0xac0000ff kind=REQUEST) refcount to -7 stderr[8]: decr 0x15f8048 (0xac0000ff kind=REQUEST) refcount to -8 Bob Cernohous: (T/L 553) 507-253-6093 [email protected] IBM Rochester, Building 030-2(C335), Department 61L 3605 Hwy 52 North, Rochester, MN 55901-7829

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