I believe my reasoning is correct below, but thought I would ask the group to confirm. Consider the following code snippet: --------------------- MPI_Irecv(..., MPI_ANY_SOURCE, ..., &req); /* Some other process in the communicator fails */ MPI_Test(&req, &flag, &status); --------------------- The proposal in #323 says that the request should be marked as MPI_ERR_PENDING and not complete. So what should the value of 'flag' and 'status' be when returning from MPI_Test? According to the standard, 'flag = true' indicates two things: 1) the operation is completed 2) The 'status' object is set For the MPI_ANY_SOURCE case above, the operation is -not- completed, so (1) is violated; therefore I think MPI_Test should set 'flag' equal to 'false'. However, is the 'status' also not set? Should MPI_Test return MPI_SUCCESS or MPI_ERR_PENDING? If MPI_Test is to return MPI_ERR_PENDING directly, then there is no needed to inspect 'status'. However if we replace MPI_Test with MPI_Testany(1, &req, &index, &flag, &status) then the operation would return MPI_ERR_IN_STATUS, and the user must inspect the 'status' field for the true error value. So we would still set 'flag = false', but would also need to set the 'status'. That is if we want MPI_Test* return an error code that indicates that the request as 'failed, but not completed'. According to the standard, if no operation is completed then MPI_Testany "returns flag = false, returns a value of MPI_UNDEFINED in index and status is undefined." So according to the MPI_Testany logic, in this case 'flag = false', 'status is undefined', and the operation should return MPI_SUCCESS. Is that the expected behavior for the code snippet above? I think so, but I thought I would double check with the group. This means that the user can only 'see' the MPI_ERR_PENDING state of the request when they call an MPI_Wait* operation, which might not be what they would normally want to do (because they do not want to block). -- Josh -- Joshua Hursey Postdoctoral Research Associate Oak Ridge National Laboratory http://users.nccs.gov/~jjhursey