sync_daemon_mpi: give daemon a distinct PMIX_NAMESPACE#514
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The MPI sync daemon shares the traced application's inherited PMIx identity (PMIX_NAMESPACE). Two MPI instances claiming the same (namespace, rank) collide in the node-local SHM bootstrap and deadlock (n=128 --ppn 64) or abort with a truncation error (n=4). Append a fixed suffix to PMIX_NAMESPACE before any MPI call so the daemon's session gets its own WORLD. Verified on 2 nodes with THAPI_SYNC_DAEMON=mpi: fix -> exit 0, full tally; control (fix disabled) -> hang. Default remains fs pending MPICH feedback. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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Related to pmodels/mpich#7852 |
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The MPI sync daemon shares the traced application's inherited PMIx identity (PMIX_NAMESPACE). Two MPI instances claiming the same (namespace, rank) collide in the node-local SHM bootstrap and deadlock (n=128 --ppn 64) or abort with a truncation error (n=4).
Append a fixed suffix to PMIX_NAMESPACE before any MPI call so the daemon's session gets its own WORLD. Verified on 2 nodes with THAPI_SYNC_DAEMON=mpi: fix -> exit 0, full tally; control (fix disabled) -> hang. Default remains fs pending MPICH feedback.