Dear all, I used mpich-3.0.1 with debugging options and the program ran correctly but at the end returned some errors indicated later. I thank mpich for finding those errors that other mpi implementation did not find but I wonder if there is a way to transform this into more useful debugging informations. Mathieu PS: The errors retuned after leaving: leaked context IDs detected: mask=0x9d7380 mask[0]=0x3fffffff In direct memory block for handle type GROUP, 3 handles are still allocated leaked context IDs detected: mask=0x9d7380 mask[0]=0x3fffffff In direct memory block for handle type GROUP, 3 handles are still allocated leaked context IDs detected: mask=0x9d7380 mask[0]=0x3fffffff In direct memory block for handle type GROUP, 3 handles are still allocated In direct memory block for handle type REQUEST, 8 handles are still allocated In indirect memory block 0 for handle type REQUEST, 191 handles are still allocated In direct memory block for handle type REQUEST, 8 handles are still allocated In indirect memory block 0 for handle type REQUEST, 190 handles are still allocated In direct memory block for handle type COMM, 4 handles are still allocated In direct memory block for handle type REQUEST, 8 handles are still allocated In indirect memory block 0 for handle type REQUEST, 187 handles are still allocated In direct memory block for handle type COMM, 4 handles are still allocated In direct memory block for handle type DATATYPE, 3 handles are still allocated In indirect memory block 0 for handle type DATATYPE, 1 handles are still allocated In direct memory block for handle type DATATYPE, 3 handles are still allocated In indirect memory block 0 for handle type DATATYPE, 1 handles are still allocated In direct memory block for handle type COMM, 4 handles are still allocated In indirect memory block 0 for handle type COMM, 2 handles are still allocated In direct memory block for handle type DATATYPE, 3 handles are still allocated In indirect memory block 0 for handle type DATATYPE, 1 handles are still allocated