Intel® MPI Library

Developer Guide for Linux* OS

ID 768728
Date 6/30/2025
Public

Visible to Intel only — GUID: GUID-64EB3EC3-2DCD-41B0-89F7-E833EECAAE43

Document Table of Contents

Error Message: Too Many Communicators

Error Message

Abort(136403471) on node 0 (rank 0 in comm 0): Fatal error in internal_Comm_dup: Other MPI error, error stack:
internal_Comm_dup(24268)............: MPI_Comm_dup(MPI_COMM_WORLD, newcomm=0x75fe1d097008) failed
MPIR_Comm_dup_impl(738).............:
MPII_Comm_dup(1207).................:
MPII_Comm_copy(1249)................:
MPIR_Get_contextid_sparse_group(609): Too many communicators (0/32768 free on this process; ignore_id=0)

Cause

MPI has a limitation on how many communicators can be created. The maximum number of communicators that can be created is 32766, with MPI_COMM_WORLD and MPI_COMM_SELF consuming allocations. Remote Memory Access (RMA) type windows will also affect this number because each window that has been created consumes a communicator for internal needs. The actual number of communicators that can be created may be less if an application creates communicators with similar groups but varying communicator IDs.

NOTE:
This is one example of an error caused by no free communicators. If you have overridden error-handling logic, you may only receive an error code but no backtrace.

Solution

To fix this issue, it is recommended that any unused MPI objects be freed using the function MPI_COMM_FREE.