Re: [Boost-users] boostMPI asychronous communication

Subject: Re: [Boost-users] boostMPI asychronous communication
From: Jack Bryan (dtustudy68_at_[hidden])
Date: 2010-06-28 19:23:11

Thanks
I have replaced the main loop with your code. 
but, it is still deadlock. 
Any help is appreciated.
Jack
June 28  2010

> Date: Mon, 28 Jun 2010 21:28:47 +0200
> From: riccardo.murri_at_[hidden]
> To: boost-users_at_[hidden]
> Subject: Re: [Boost-users] boostMPI asychronous communication
> 
> Hello Jack,
> 
> On Mon, Jun 28, 2010 at 7:46 PM, Jack Bryan <dtustudy68_at_[hidden]> wrote:
> > This is the main part of me code, which may have deadlock.
> >
> > Master:
> > for (iRank = 0; iRank < availableRank ; iRank++)
> > {
> > destRank = iRank+1;
> > for (taski = 1; taski <=  TaskNumPerRank ; taski++)
> > {
> > resultSourceRank = destRank;
> > recvReqs[taskCounterT2] = world.irecv(resultSourceRank, upStreamTaskTag, resultTaskPackageT2[iRank][taskCounterT3]);
> > reqs = world.isend(destRank, taskTag, myTaskPackage);
> > ++taskCounterT2;
> > }
> >
> > // taskTotalNum = availableRank * TaskNumPerRank
> > // right now, availableRank =1, TaskNumPerRank =2
> > mpi::wait_all(recvReqs, recvReqs+(taskTotalNum));
> > -----------------------------------------------
> > worker:
> > while (1)
> > {
> > world.recv(managerRank, downStreamTaskTag, resultTaskPackageW);
> > do its local work on received task;
> > destRank = masterRank;
> > reqs = world.isend(destRank, taskTag, myTaskPackage);
> > if (recv end signal)
> >   break;
> > }
> 
> 1. I can't see where the outer for-loop in master is closed; is the
> wait_all() part of that loop?  (I assume it does not.)  Can you send a
> minimal program that I can feed to a compiler and test?  This could
> help.
> 
> 2. Are you sure there is no tag mismatch between master and worker?
> 
>   master:  world.isend(destRank, taskTag, myTaskPackage);
>                                  ^^^^^^^
>   worker:  world.recv(managerRank, downStreamTaskTag, resultTaskPackageW);
>                                    ^^^^^^^^^^^^^^^^^
> 
> unless master::taskTag == worker::downStreamTaskTag, the recv() will
> wait forever.
> 
> Similarly, the following requires that master::upStreamTaskTag ==
> worker::taskTag:
> 
>   master:  ... = world.irecv(resultSourceRank, upStreamTaskTag, ...);
>   worker:  world.isend(destRank, taskTag, myTaskPackage); //
> destRank==masterRank
> 
> 3. Do the source/destination ranks match?  The master waits for messages from
> destinations 1..availableRank (inclusive range), and the worker waits
> for a message from "masterRank" (is this 0?)
> 
> 4. Does the master work if you replace the main loop with the following?
> 
>     Master:
>     for (iRank = 0; iRank < availableRank ; iRank++)
>     {
>       destRank = iRank+1;
>       for (taski = 1; taski <=  TaskNumPerRank ; taski++)
>         {
>           // XXX: the following code does not contain any reference to
>           // "taski": it is sending "TaskNumPerRank" copies of the
>           // same message ...
>           reqs = world.isend(destRank, taskTag, myTaskPackage);
>         };
>     }; // I assume the outer loop does *not* include the wait_all()
> 
>     // expect a message from each Task
>     int n = 0;
>     while (n < taskTotalNum) {
>       mpi::status status = world.probe();
>       world.recv(status.source(), status.tag(),
>                  resultTaskPackageT2[status.source()][taskCounterT3]);
>       ++n;
>     };
> 
> 
> Best regards,
> Riccardo
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