I'm afraid I don't know what you mean by THREAD_SEQUENTIAL. Do you
mean THREAD_SERIALIZED?
LAM is not thread safe nor it is thread concurrent -- so the type of
behavior you're trying to do just won't work with LAM. Sorry. :-(
On the upside, Open MPI is capable of this kind of behavior. :-)
On Mar 4, 2005, at 11:25 AM, David Cronk wrote:
> I re-read the standard. I don't know what I read before, but I was
> clearly mistaken on what MPI_THREAD_SEQUENTIAL meant. This is the
> expected behavior. Clearly I cannot have a thread doing blocking
> calls. Fairly useless, really, in terms of multi-threading.
>
> Dave.
>
> David Cronk wrote:
>> I think this is a bug. I am attaching two programs to demonstrate
>> the problem. To run the tests, compile serv.c with -lpthread and
>> then run it in the background. Note that the call to sleep is there
>> only to force some timing. After serv is running, compile and run
>> work.c
>> What seems to be happening is, a thread in serv posts an
>> MPI_Comm_accept. Once work connects, the thread in serv creates
>> another thread to look for other connecting processes, before trying
>> to receive data from the already connected process. The newly
>> created thread gets on the processor and posts an MPI_Comm_accept.
>> The previous thread then gets back on the processor and tries to
>> receive the data sent by work. However, this data never seems to
>> arrive and we are in deadlock. As far as I can tell from reading the
>> standard, this is incorrect behavior for MPI_THREAD_SEQUENTIAL.
>> Unless, of course, I am missing something in the code that is causing
>> the deadlock.
>> Dave.
>> ----------------------------------------------------------------------
>> --
>> #include <stdlib.h>
>> #include <stdio.h>
>> #include <mpi.h>
>> #include <signal.h>
>> #include <pthread.h>
>> #include "head.h" int nodelist[NUMNODES];
>> char myport[MPI_MAX_PORT_NAME]; pthread_cond_t cond;
>> pthread_mutex_t lock;
>> pthread_attr_t attr; int active; void *service_thread (void *arg)
>> {
>> int node, mintasks, i, provided;
>> int target; MPI_Comm communicator; MPI_Status status; pthread_t
>> thr_id; int pid = getpid();
>> printf ("[%d] service_thread is ALIVE!\n", pid); fflush (stdout);
>> MPI_Comm_accept (myport, MPI_INFO_NULL, 0, MPI_COMM_WORLD,
>> &communicator);
>> printf ("[%d] service_thread Accepted!\n", pid); fflush (stdout);
>> pthread_create (&thr_id, &attr, service_thread, NULL); sleep(2);
>> while (1) { printf ("[%d] service_thread about to receive!\n",
>> pid); fflush (stdout); MPI_Recv (&node, 1, MPI_INT, 0,
>> MPI_ANY_TAG, communicator, &status); printf ("[%d] service_thread
>> received %d \n", pid, status.MPI_TAG); fflush (stdout); if
>> (status.MPI_TAG == DONE_TAG) { break; }
>> if (status.MPI_TAG == NEW_TAG) { active++;
>> printf ("[%d] service_thread sending \n", pid); fflush
>> (stdout); MPI_Send (&active, 1, MPI_INT, 0, MSG_TAG,
>> communicator); printf ("[%d] service_thread sent \n", pid);
>> fflush (stdout); } }
>> MPI_Comm_disconnect (&communicator);
>> }
>> int main(int argc, char *argv[])
>> //---------------------------------
>> {
>> int i, provided;
>> pthread_t thr_id; MPI_Init_thread(&argc, &argv,
>> MPI_THREAD_MULTIPLE, &provided);
>> if (provided < MPI_THREAD_SERIALIZED) {
>> printf ("This MPI implementation does not support a high enough
>> level of thread support. Aborting tasker!\n");
>> exit (1);
>> }
>> MPI_Open_port (MPI_INFO_NULL, myport); MPI_Publish_name
>> ("tasker", MPI_INFO_NULL, myport);
>> pthread_attr_init (&attr);
>> pthread_attr_setdetachstate (&attr, PTHREAD_CREATE_DETACHED);
>> // Initialize lists for (i=0; i<NUMNODES; i++)
>> nodelist[i] = 0;
>> active = 1; pthread_create (&thr_id, &attr, service_thread,
>> NULL); while (1); MPI_Finalize();
>> exit(0);
>> }
>> ----------------------------------------------------------------------
>> --
>> #include <stdlib.h>
>> #include <stdio.h>
>> #include <mpi.h>
>> #include <sys/types.h>
>> #include <signal.h>
>> #include "head.h"
>> int self;
>> MPI_Comm taskcomm; MPI_Info sp_info; int main(int argc, char *argv[])
>> //---------------------------------
>> {
>> int node;
>> MPI_Status status; int errcode[1]; char
>> portname[MPI_MAX_PORT_NAME];
>> char nodestr[6]; MPI_Init(&argc, &argv);
>> MPI_Comm_rank(MPI_COMM_WORLD, &self);
>> printf ("about to lookup\n"); fflush (stdout);
>> MPI_Lookup_name ("tasker", MPI_INFO_NULL, portname); printf
>> ("portname = %s\n", portname); fflush (stdout);
>> MPI_Comm_connect (portname, MPI_INFO_NULL, 0, MPI_COMM_SELF,
>> &taskcomm);
>> printf ("connected \n"); fflush (stdout);
>> MPI_Info_create (&sp_info);
>> printf ("sending to server \n"); fflush (stdout);
>> MPI_Send (&node, 0, MPI_INT, 0, NEW_TAG, taskcomm);
>> printf ("receiving from server \n"); fflush (stdout);
>> MPI_Recv (&node, 1, MPI_INT, 0, MSG_TAG, taskcomm, &status);
>> printf ("sending to server node = %d\n", node); fflush (stdout);
>> MPI_Send (&node, 0, MPI_INT, 0, NEW_TAG, taskcomm);
>> printf ("receiving from server \n"); fflush (stdout);
>> MPI_Recv (&node, 1, MPI_INT, 0, MSG_TAG, taskcomm, &status);
>> printf ("received from server node = %d\n", node); fflush
>> (stdout);
>> sprintf (nodestr, "n%d", node); MPI_Info_set (sp_info,
>> "lam_spawn_sched_round_robin", nodestr); printf ("sending
>> done_tag to server \n"); fflush (stdout);
>> MPI_Send (&self, 0, MPI_INT, 0, DONE_TAG, taskcomm);
>> printf ("disconnecting from server \n"); fflush (stdout);
>> MPI_Comm_disconnect (&taskcomm); MPI_Finalize();
>> exit(0);
>> }
>> ----------------------------------------------------------------------
>> --
>> ----------------------------------------------------------------------
>> --
>> _______________________________________________
>> This list is archived at http://www.lam-mpi.org/MailArchives/lam/
>
> --
> Dr. David Cronk, Ph.D. phone: (865) 974-3735
> Research Leader fax: (865) 974-8296
> Innovative Computing Lab
> http://www.cs.utk.edu/~cronk
> University of Tennessee, Knoxville
> _______________________________________________
> This list is archived at http://www.lam-mpi.org/MailArchives/lam/
>
--
{+} Jeff Squyres
{+} jsquyres_at_[hidden]
{+} http://www.lam-mpi.org/
|
