Hmm. This will not work. You are simultaneously doing two collectives on the same communicator (MPI_COMM_SELF) from two different threads: MPI_Comm_accept and MPI_Comm_connect. This is not allowed by the MPI standard. — Pavan P.S.: Sorry, I should have caught that yesterday. It’s amazing what a good night’s sleep can do! On Oct 8, 2014, at 12:14 AM, Roy, Hirak <[email protected]> wrote:

Hi Pavan,

Here is my code for thread2 :

do { MPI_Comm newComm ; MPI_Comm_accept (m_serverPort.c_str(), MPI_INFO_NULL, 0, MPI_COMM_SELF, &newComm); Log ("Accepted a connection"); int buf = 0 ; MPI_Status status ; MPI_Recv(&buf, 1, MPI_INT, MPI_ANY_SOURCE, MPI_ANY_TAG, newComm, &status);

if (status.MPI_TAG == MPI_MSG_TAG_NEW_CONN) { m_clientComs[m_clientCount] = newComm ; m_clientCount++; } else if (status.MPI_TAG == MPI_MSG_TAG_SHUTDOWN) { Log ("Shutdown"); //MPI_Comm_disconnect (&newComm); Log ("Disconnect"); break; } else { Log ("Unmatched Receive"); } } while(1) ;

Here is my code for thread1 to terminate thread2 :

MPI_Comm newComm ; MPI_Comm_connect (m_serverPort.c_str(), MPI_INFO_NULL, 0, MPI_COMM_SELF, &newComm); Log ("Connect to Self"); int val = 0 ; MPI_Request req ; MPI_Send(&val, 1, MPI_INT, 0, MPI_MSG_TAG_SHUTDOWN, newComm); Log ("Successful"); //MPI_Status stat ; //MPI_Wait(&req, &stat); Log ("Complete");

//MPI_Comm_disconnect(&newComm);

The MPI_Send/Recv waits. I am using sock channel. For nemesis, I get the following crash : Assertion failed in file ./src/mpid/ch3/channels/nemesis/include/mpid_nem_inline.h at line 58: vc_ch->is_local internal ABORT - process 0

I tried non-blocking send and receive followed by wait. However, that also does not solve the problem.

Thanks, Hirak

-----

Hirak,

Your approach should work fine. I’m not sure what issue you are facing. I assume thread 1 is doing this:

while (1) { MPI_Comm_accept(..); MPI_Recv(.., tag, ..); if (tag == REGULAR_CONNECTION) continue; else if (tag == TERMINATION) { MPI_Send(..); break; } }

In this case, all clients do an MPI_Comm_connect and then send a message with tag = REGULAR_CONNECTION. When thread 2 is done with its work, it’ll do an MPI_Comm_connect and then send a message with tag = TERMINATION, wait for a response from thread 1, and call finalize.

— Pavan

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-- Pavan Balaji ✉️ http://www.mcs.anl.gov/~balaji _______________________________________________ discuss mailing list [email protected] To manage subscription options or unsubscribe: https://lists.mpich.org/mailman/listinfo/discuss