For the reduce function request the size of the communicator prior to allocating memory as the size is used for that.

This commit was SVN r1515.

src/mca/coll/basic/src/coll_basic_reduce.c

@@ -263,6 +263,13 @@ int mca_coll_basic_reduce_log_intra(void *sbuf, void *rbuf, int count,
   void *inmsg;
   void *resmsg;
 
+  /* Some variables */
+
+  size = ompi_comm_size(comm);
+  rank = ompi_comm_rank(comm);                       
+  vrank = ompi_op_is_commute(op) ? (rank - root + size) % size : rank;
+  dim = comm->c_cube_dim;
+
   /* Allocate the incoming and resulting message buffers.  See lengthy
      rationale above. */
 
@@ -279,13 +286,6 @@ int mca_coll_basic_reduce_log_intra(void *sbuf, void *rbuf, int count,
     pml_buffer2 = free_buffer - lb;
   }
 
-  /* Some variables */
-
-  size = ompi_comm_size(comm);
-  rank = ompi_comm_rank(comm);                       
-  vrank = ompi_op_is_commute(op) ? (rank - root + size) % size : rank;
-  dim = comm->c_cube_dim;
-
   /* Loop over cube dimensions. High processes send to low ones in the
      dimension. */