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From: imran shaik (sk.imran_at_[hidden])
Date: 2006-05-27 01:31:21


Hi jeff,
  thanks for your comprehensive reply.
  I have installed openMPI alpha 7 release. I created an MPI programs with pthreads. I ran with just 6 process, each thread making MPI calls concurrently with main thread. Things work fine . I use a TCP network.
  
  Some times i get a strange error message.
  
  I am sending some output of my program.
  -----------------------------------------------------------------
  
  mca_btl_sm_send: write fifo failed: errno=9
  P=1 Response sent for 8 to node 2
  P= 1 listen:Itrcnt=3
  RF-> P=5 resrc= 8 origin= 2 Prev node= 3 -> 1
  P= 5 listen:Itrcnt=3
  P= 3Recvd: Source= 5 tag= 5
  RF-> P=3 resrc= 10 origin= 1 Prev node= 5 -> 2
  P= 3 listen:Itrcnt=4
  P= 2Recvd: Source= 3 tag= 4
  P= 1Recvd: Source= 2 tag= 31
  Yahoo! FP=1 Node=2 has 1 matches for 10 Hopcount=5
  P=1 Req for 10 was fwded to 0
  P=1 Index of 0 is 0
  P=1 Updating neighbor index of 0
  P=1 expbase[0]=1
  P= 1 listen:Itrcnt=4
  P=2 Response sent for 10 to node 1
  P= 2 listen:Itrcnt=2
  P= 2Recvd: Source= 1 tag= 31
  Yahoo! FP=2 Node=1 has 1 matches for 8 Hopcount=3
  P=2 Req for 8 was fwded to 3
  P=2 Index of 3 is 1
  P=2 Updating neighbor index of 3
  P=2 expbase[1]=1
  P= 2 listen:Itrcnt=3
  P=5 RN=8
  P=5 NA=8 RF-->3
  P= 3Recvd: Source= 5 tag= 8
  RF-> P=3 resrc= 8 origin= 5 Prev node= 5 -> 4
  P= 3 listen:Itrcnt=5
  P= 4Recvd: Source= 3 tag= 7
  P= 3Recvd: Source= 4 tag= 6
  RF-> P=4 resrc= 8 origin= 5 Prev node= 3 -> 3
  P= 4 listen:Itrcnt=3
  RF-> P=3 resrc= 8 origin= 5 Prev node= 4 -> 2
  P= 3 listen:Itrcnt=6
  P= 2Recvd: Source= 3 tag= 5
  RF-> P=2 resrc= 8 origin= 5 Prev node= 3 -> 1
  P= 2 listen:Itrcnt=4
  P= 1Recvd: Source= 2 tag= 4
  [Neelw5:12103] mca_btl_sm_send: write fifo failed: errno=9
  --------------------------------------------------------------------------------------
  
  Sometimes i get this error message, and sometimes not. I can say in a run of 7 i get once. But i get the output properly and the program works fine. I just wanted to know why that occured?
  
  
  Another one, i tried to get verbose output from "mpirun", but couldnt. Even "mpiexec". I was using the same command as
  mpirun -v -np 6 myprogram in lam, i used to get the verbose saying which process is running where. Here nothing happens.
  
  What is the problem? Otherwise how can i know what process is running on what node? Any suggestions??
  
  Thanks in advance,,
  
  Regards,
  Imran
  
  

"Jeff Squyres (jsquyres)" <jsquyres_at_[hidden]> wrote: MPI_THREAD_MULITPLE is "somewhat" supported, meaning that support for it was designed in to Open MPI, but it has not been fully stress tested. As such, there is likely to still be bugs when using multiple user threads with MPI_THREAD_MULTIPLE.
   
  fork() is not technically supported by the MPI standard. If you *need* to fork(), you might want to look at alternate mechanisms if you need to move between multiple MPI implementations because support for it is not likely to be portable.
   
  Within Open MPI, fork() will almost certainly fail if you use the OS-bypass networks (Myrinet, InfiniBand). The mechanisms that these networks use for high-speed/low latency are quite problematic with fork(). If you are using tcp or shared memory, fork() *might* work, but this is not something that we have extensively tested.

          
---------------------------------
    From: users-bounces_at_[hidden] [mailto:users-bounces_at_[hidden]] On Behalf Of imran shaik
Sent: Friday, May 26, 2006 1:50 AM
To: openMPI mailing list
Subject: [OMPI users] Thread Safety

    
Hi,
I am a newbie to OpenMPI.
Can anyone say how the support for MPI_THREAD_MULTIPLE is implemented in openMPI?

Is thread safety completely provided in openMPI? or does it still has some bugs?
I am currently using LAM/MPI.But i need concurrent threads making MPI calls. So i am planning to move to another implementation of MPI. Can i choose openMPI?

Also, is "fork"(for child preoces creation) still a no-no in openMPI too? Can a child process(forked) make concurrent MPI calls along with its parent ?

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