Pavan,

Is there any way to come out of the blocking accept?

Thanks,

Hirak

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 <Hirak_Roy at mentor.com> 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

>