[mpich-discuss] Question reg usage with MPI_THREAD_MULTIPLE

[Ramesh Vinayagam]

I use the  version 1.4.1 and adding the pthread.h  did make it work

Thanks
Ramesh


On Tue, Jun 26, 2012 at 7:49 AM, Darius Buntinas <buntinas at mcs.anl.gov>wrote:

> What's the output you see?
>
> -d
>
> On Jun 25, 2012, at 10:31 PM, Ramesh Vinayagam wrote:
>
> > It hangs at the pthread join of the second process, which did not make
> sense because its the same way I use for the first process, also I use
> different communicators for communication.
> >
> >
> > Thanks
> >
> >
> > On Mon, Jun 25, 2012 at 5:50 PM, Darius Buntinas <buntinas at mcs.anl.gov>
> wrote:
> > I didn't test your program, but I didn't see any obvious problems.
>  MPICH does support using threads in the way you described.  What is the
> output you get?  Where does it hang?
> >
> > -d
> >
> >
> > On Jun 25, 2012, at 5:58 PM, Ramesh Vinayagam wrote:
> >
> > > Hello,
> > >
> > >
> > > I having a question regarding the usage of MPI_THREAD_MULTIPLE.
> > >
> > > I was wondering whether this scenario works with MPI
> > >
> > > Process 0
> > > Thread 1 -> probes and receives
> > > Thread 2 -> Sends to  process 0
> > >
> > > Process 1
> > >
> > > Thread 1 -> probes and receives
> > > Thread 2 -> Sends to  process 1
> > >
> > > I wrote a simple code, and it seems to hang with mpich2. I am not sure
> whether or not this feature is supported with MPI, can anyone let me know
> whether what I do here is correct or wrong?
> > >
> > >
> > > Here is the code.. This code hangs when I use it with two processes.
> It works with one process.
> > >
> > > Thanks
> > > Ramesh
> > >
> ____________________________________________________________________________________________________________________________________________________
> > > #include <stdio.h>
> > > #include <stdlib.h>
> > > #include <mpi.h>
> > > #include <string.h>
> > > #include <assert.h>
> > >
> > > typedef struct
> > > {
> > >   int thread;
> > >   MPI_Comm comm;
> > >   int rank;
> > > } thdata;
> > >
> > > void probe_recv (void *ptr){
> > >   thdata *data;
> > >   data = (thdata *) ptr;
> > >   int count, flag = 0;
> > >   MPI_Status status;
> > >   char buf[256];
> > >
> > >   printf("%d :Thread :%d Prbes and receives \n", data->rank,
> data->thread);
> > >   while (!flag){
> > >     MPI_Iprobe(data->rank, 0, data->comm, &flag, &status);
> > >   }
> > >   MPI_Get_count( &status, MPI_CHAR, &count);
> > >   printf("%d :Thread :%d count : %d \n", data->rank, data->thread,
> count);
> > >
> > >   MPI_Recv( &buf,
> > >           count,
> > >           MPI_CHAR,
> > >           data->rank,
> > >           status.MPI_TAG,
> > >           data->comm,
> > >           MPI_STATUS_IGNORE);
> > >
> > >   printf("%d Message : %s \n", data->rank,buf);
> > > }
> > >
> > > void send(void *ptr){
> > >   thdata *data;
> > >   char buffer[256];
> > >   data = (thdata *) ptr;
> > >   printf("%d: Thread :%d Sends \n", data->rank, data->thread);
> > >   strcpy(buffer,"Hello World");
> > >   MPI_Send(&buffer,256, MPI_CHAR, data->rank, 0, data->comm);
> > >   printf("%d: Thread :%d send completed \n",
> > >        data->rank,
> > >        data->thread);
> > > }
> > >
> > >
> > > int main(int argc, char *argv[]){
> > >
> > >   int provided, i[2], rank, size;
> > >   MPI_Status  status;
> > >   pthread_t thread_a, thread_b;
> > >   MPI_Comm communicator[2];
> > >   thdata data1, data2;
> > >
> > >   MPI_Init_thread(&argc, &argv, MPI_THREAD_MULTIPLE, &provided);
> > >
> > >   if (provided != MPI_THREAD_MULTIPLE){
> > >       printf("Error\n");
> > >       MPI_Abort(911, MPI_COMM_WORLD);
> > >   }
> > >   MPI_Comm_rank(MPI_COMM_WORLD, &rank);
> > >   MPI_Comm_size(MPI_COMM_WORLD, &size);
> > >   assert (size == 2);
> > >   MPI_Comm_dup(MPI_COMM_WORLD,&communicator[rank]);
> > >
> > >   data1.comm = communicator[rank];
> > >   data1.thread = 1;
> > >   data1.rank = rank;
> > >   pthread_create (&thread_a, NULL, (void *) &probe_recv, (void
> *)&data1);
> > >
> > >   data2.comm = communicator[rank];
> > >   data2.thread = 2;
> > >   data2.rank = rank;
> > >   pthread_create (&thread_b, NULL, (void *) &send, (void *)&data2);
> > >
> > >   pthread_join(thread_a, NULL);
> > >   pthread_join(thread_b, NULL);
> > >   MPI_Finalize();
> > > }
> > >
> > >
> > >
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