The call of MPI_Gather with sendbuf and sendtype parameters equal to MPI_IN_PLACE and NULL correspondingly, produces the segmentation fault in the root process.
The problem is that sendtype is used even when sendbuf value is MPI_IN_PLACE. But according to the standard (page 150, line 37), sendtype and sendcount parameters should be ignored in this case.
Signed-off-by: Mikhail Kurnosov <mkurnosov@gmail.com>
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