Re: [OMPI users] MPI group and stuck in communication

[Diego Avesani]

Dear George, Dear Gilles, Dear Jeff, Deal all,

Thank for all the suggestions.
The problem is that I do not want to FINALIZE, but only to exit from a
cycle.
This is my code:
I have:
master_group;
each master sends to its slaves only some values;
the slaves perform something;
according to a counter, every processor has to leave a cycle.

Here an example, if you want I can give you more details.

DO iRun=1,nRun
   !
   IF(MPI_COMM_NULL .NE. MPI_MASTER_COMM)THEN
  VARS(1) = REAL(iRun+1)
  VARS(2) = REAL(iRun+100)
  VARS(3) = REAL(iRun+200)
  VARS(4) = REAL(iRun+300)
   ENDIF
   !
   CALL MPI_BCAST(VARS,4,MPI_DOUBLE_PRECISION,0,MPI_LOCAL_COMM,iErr)
   !
   test = SUM(VARS)
   !
   CALL MPI_ALLREDUCE(test, test, 1, MPI_DOUBLE_PRECISION, MPI_SUM,
MPI_LOCAL_COMM,iErr)
   !
   !
   counter = test
   !
   CALL MPI_ALLREDUCE(counter, counter, 1, MPI_DOUBLE_PRECISION, MPI_SUM,
MPI_MASTER_COMM,iErr)
   !
   IF(counter.GT.1)THEN
  EXIT
   ENDIF
ENDDO

My original code stucks on the cycle and I do not know why.

Thanks





Diego


On 13 August 2018 at 23:44, George Reeke  wrote:

>
> > On Aug 12, 2018, at 2:18 PM, Diego Avesani
> >  wrote:
> > >
> > > For example, I have to exit to a cycle, according to a
> > check:
> > >
> > > IF(counter.GE.npercstop*nParticles)THEN
> > > flag2exit=1
> > > WRITE(*,*) '-Warning PSO has been exit'
> > > EXIT pso_cycle
> > >  ENDIF
> > >
> > > But this is difficult to do since I have to exit only after
> > all the threats inside a set have finish their task.
> > >
> > > Do you have some suggestions?
> > > Do you need other information?
> >
> Dear Diego et al,
> Assuming I understand your problem:
> The way I do this is set up one process that is responsible for normal
> and error exits.  It sits looking for messages from all the other ranks
> that are doing work.  Certain messages are defined to indicate an error
> exit with an error number or some text.  The exit process is spawned by
> the master process at startup and is told how many working processes are
> there.  Each process either sends an OK exit when it is done or an error
> message.  The exit process counts these exit messages and when the count
> equals the number of working processes, it prints any/all errors, then
> sends messages back to all the working processes, which, at this time,
> should be waiting for these and they can terminate with MPI_Finalize.
>Of course it is more complicated than that to handle special cases
> like termination before everything has really started or when the
> protocol is not followed, debug messages that do not initiate
> termination, etc. but maybe this will give you an idea for one
> way to deal with this issue.
> George Reeke
>
>
>
>
> ___
> users mailing list
> users@lists.open-mpi.org
> https://lists.open-mpi.org/mailman/listinfo/users
>
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Re: [OMPI users] MPI group and stuck in communication

[Gilles Gouaillardet]

Diego,


first, try using MPI_IN_PLACE when sendbuffer and recvbuffer are identical


at first glance, the second allreduce should be in MPI_COMM_WORLD (with 
counter=0 when master_comm is null),


or you have to add an extra broadcast in local_comm


Cheers,


Gilles


On 8/20/2018 3:56 PM, Diego Avesani wrote:

Dear George, Dear Gilles, Dear Jeff, Deal all,

Thank for all the suggestions.
The problem is that I do not want to FINALIZE, but only to exit from a 
cycle.

This is my code:
I have:
master_group;
each master sends to its slaves only some values;
the slaves perform something;
according to a counter, every processor has to leave a cycle.

Here an example, if you want I can give you more details.

DO iRun=1,nRun
   !
   IF(MPI_COMM_NULL .NE. MPI_MASTER_COMM)THEN
      VARS(1) = REAL(iRun+1)
      VARS(2) = REAL(iRun+100)
      VARS(3) = REAL(iRun+200)
      VARS(4) = REAL(iRun+300)
   ENDIF
   !
   CALL MPI_BCAST(VARS,4,MPI_DOUBLE_PRECISION,0,MPI_LOCAL_COMM,iErr)
   !
   test = SUM(VARS)
   !
   CALL MPI_ALLREDUCE(test, test, 1, MPI_DOUBLE_PRECISION, MPI_SUM, 
MPI_LOCAL_COMM,iErr)

   !
   !
   counter = test
   !
   CALL MPI_ALLREDUCE(counter, counter, 1, MPI_DOUBLE_PRECISION, 
MPI_SUM, MPI_MASTER_COMM,iErr)

   !
   IF(counter.GT.1)THEN
      EXIT
   ENDIF
ENDDO

My original code stucks on the cycle and I do not know why.

Thanks





Diego


On 13 August 2018 at 23:44, George Reeke > wrote:



>         On Aug 12, 2018, at 2:18 PM, Diego Avesani
>         mailto:diego.aves...@gmail.com>> wrote:
>         >
>         > For example, I have to exit to a cycle, according to a
>         check:
>         >
>         > IF(counter.GE.npercstop*nParticles)THEN
>         >         flag2exit=1
>         >         WRITE(*,*) '-Warning PSO has been exit'
>         >         EXIT pso_cycle
>         >      ENDIF
>         >
>         > But this is difficult to do since I have to exit only
after
>         all the threats inside a set have finish their task.
>         >
>         > Do you have some suggestions?
>         > Do you need other information?
>
Dear Diego et al,
Assuming I understand your problem:
The way I do this is set up one process that is responsible for normal
and error exits.  It sits looking for messages from all the other
ranks
that are doing work.  Certain messages are defined to indicate an
error
exit with an error number or some text.  The exit process is
spawned by
the master process at startup and is told how many working
processes are
there.  Each process either sends an OK exit when it is done or an
error
message.  The exit process counts these exit messages and when the
count
equals the number of working processes, it prints any/all errors, then
sends messages back to all the working processes, which, at this time,
should be waiting for these and they can terminate with MPI_Finalize.
   Of course it is more complicated than that to handle special cases
like termination before everything has really started or when the
protocol is not followed, debug messages that do not initiate
termination, etc. but maybe this will give you an idea for one
way to deal with this issue.
George Reeke




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