> Date: Mon, 28 Jun 2010 21:28:47 +0200
> From: riccardo.murri@gmail.com
> To: boost-users@lists.boost.org
> Subject: Re: [Boost-users] boostMPI asychronous communication
>
> Hello Jack,
>
> On Mon, Jun 28, 2010 at 7:46 PM, Jack Bryan <dtustudy68@hotmail.com> 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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