The following snippet, previously discussed on SO and validated with MPICH, OpenMPI and Intel MPI is not working properly with MS-MPI 10.0.12498.5.
In a thread, a loop continuously listen to requests with consecutive calls to MPI_Irecv and MPI_Wait. To exit the loop cleanly, MPI_Cancel is called from another thread to cancel the request. According to the standard:
If a communication is marked for cancellation, then a MPI_WAIT call for that communication is guaranteed to return.
#include <mpi.h>
#include <iostream>
#include <future>
using namespace std::literals::chrono_literals;
void async_cancel(MPI_Request *request)
{
std::this_thread::sleep_for(1s);
std::cout << "Before MPI_Cancel" << std::endl;
int res = MPI_Cancel(request);
if (res != MPI_SUCCESS)
std::cerr << "MPI_Cancel failed" << std::endl;
std::cout << "After MPI_Cancel" << std::endl;
}
int main(int argc, char* argv[])
{
int provided;
MPI_Init_thread(&argc, &argv, MPI_THREAD_MULTIPLE, &provided);
if (provided != MPI_THREAD_MULTIPLE)
std::cout << "MPI_Init_thread could not provide MPI_THREAD_MULTIPLE" << std::endl;
int rank, numprocs;
MPI_Comm_size(MPI_COMM_WORLD, &numprocs);
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
MPI_Request request;
MPI_Status status;
int buffer;
if (rank == 0)
{
MPI_Irecv(&buffer, 1, MPI_INT, 1, 123, MPI_COMM_WORLD, &request);
auto res = std::async(std::launch::async, &async_cancel, &request);
std::cout << "Before MPI_Wait" << std::endl;
MPI_Wait(&request, &status);
std::cout << "After MPI_Wait " << std::endl;
}
else
std::this_thread::sleep_for(2s);
MPI_Finalize();
return 0;
}
The expected result is:
Before MPI_Wait
Before MPI_Cancel
After MPI_Cancel
After MPI_Wait
The following snippet, previously discussed on SO and validated with MPICH, OpenMPI and Intel MPI is not working properly with MS-MPI 10.0.12498.5.
In a thread, a loop continuously listen to requests with consecutive calls to
MPI_Irecv
andMPI_Wait
. To exit the loop cleanly,MPI_Cancel
is called from another thread to cancel the request. According to the standard:The expected result is:
With MS-MPI,
MPI_Wait()
does not return.