To Whom This May Concern: I am having problems with an OpenMPI application I am writing on the Solaris/Intel AMD64 platform. I am using OpenMPI 1.3.2 which I compiled myself using the Solaris C/C++ compiler.
My application was crashing (signal 11) inside a call to malloc() which my code was running. I thought it might be a memory overflow error that was causing this, so I fired up Purify. Purify found several problems inside the the OpenMPI library. I think one of the errors is serious and might be causing the problems I was looking for. The serious error is an Array Bounds Write (ABW) which occurred 824 times through 312 calls to MPI_Recv(). This error means that something inside the OpenMPI library is writing to memory where it shouldn't be writing to. Here is the stack trace at the time of this error: Stack Trace 1 (Occurred 596 times) memcpy rtlib.o unpack_predefined_data [datatype_unpack.h:41] MEMCPY_CSUM( _destination, *(SOURCE), _copy_blength, (CONVERTOR) ); ompi_generic_simple_unpack [datatype_unpack.c:419] ompi_convertor_unpack [convertor.c:314] mca_pml_ob1_recv_frag_callback_match [pml_ob1_recvfrag.c:218] mca_btl_sm_component_progress [btl_sm_component.c:427] opal_progress [opal_progress.c:207] opal_condition_wait [condition.h:99] <Writing 64 bytes to 0x821f738 in heap (16 bytes at 0x821f768 illegal).> <Address 0x821f738 is 616 bytes into a malloc'd block at 0x821f4d0 of 664 bytes.> Stack Trace 2 (Occurred 228 times) memcpy rtlib.o unpack_predefined_data [datatype_unpack.h:41] MEMCPY_CSUM( _destination, *(SOURCE), _copy_blength, (CONVERTOR) ); ompi_generic_simple_unpack [datatype_unpack.c:419] ompi_convertor_unpack [convertor.c:314] mca_pml_ob1_recv_request_progress_match [pml_ob1_recvreq.c:624] mca_pml_ob1_Recv_req_start [pml_ob1_recvreq.c:1008] mca_pml_ob1_recv [pml_ob1_irecv.c:103] MPI_Recv [precv.c:75] <Writing 64 bytes to 0x821f738 in heap (16 bytes at 0x821f768 illegal).> <Address 0x821f738 is 616 bytes into a malloc'd block at 0x821f4d0 of 664 bytes.> I'm not that familiar with the under workings of the openmpi library, but I tried to debug it anyway. I noticed that it was copying a lot of extra bytes for MPI_LONG and MPI_DOUBLE types. On my system, MPI_LONG should have been 4 bytes, but was copying 16 bytes. Also, MPI_DOUBLE should have been 8 bytes, but was copying 64 bytes. It seems the _copy_blength variable was being set to high, but I'm not sure why. The above error also shows 64 bytes being read, where my debugging shows a 64 byte copy for all MPI_DOUBLE types, which I feel should have been 8 bytes. Therefore, I really believe _copy_blength is being set to high. Interestingly enough, the call to MPI_Isend() was generating an ABR (Array Bounds Read) error in the exact same line of code. The ABR error sometimes can be fatal if the bytes being read is not a legal address, but the ABW error is usually a much more fatal error because it is definitely writing into memory that is probably used for something else. I'm sure that if we fix the ABW error, the ABR error should fix itself too as it's the same line of code. Purify also found 14 UMR (Uninitialized memory read) errors inside the OpenMPI library. Sometimes this can be really bad if there are any decisions being made as a result of reading this memory location. But for now, let's solve the serious error I reported above first, then I will send you the UMR errors next. Any help you can provide would be greatly appreciated. Thanks, Brian
