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Subject: Re: [OMPI users] MPI_Comm_accept() busy waiting?
From: Douglas Guptill (douglas.guptill_at_[hidden])
Date: 2010-03-09 12:05:21

On Tue, Mar 09, 2010 at 05:43:02PM +0100, Ramon wrote:
> Am I the only one experiencing such problem? Is there any solution?

No, you are not the only one. Several others have mentioned the "busy
wait" problem.

The response on the OpenMPI developers, as I understand it, is that
the MPI job should be the only one running, so a 100% busy wait is not
a problem. I hope the OpenMPI developers will correct me if I have
mis-stated their position.

I posted my cure for the problem some time ago. I have attached it
again to this message.

Hope that helps,

> Ramon wrote:
>> Hi,
>> I've recently been trying to develop a client-server distributed file
>> system (for my thesis) using the MPI. The communication between the
>> machines is working great, however when ever the MPI_Comm_accept()
>> function is called, the server starts like consuming 100% of the CPU.
>> One interesting thing is that I tried to compile the same code using
>> the LAM/MPI library and the mentioned behaviour could not be observed.
>> Is this a bug?
>> On a side note, I'm using Ubuntu 9.10's default OpenMPI deb package.
>> Its version is 1.3.2.
>> Regards
>> Ramon.
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  Douglas Guptill                       voice: 902-461-9749
  Research Assistant, LSC 4640          email: douglas.guptill_at_[hidden]
  Oceanography Department               fax:   902-494-3877
  Dalhousie University
  Halifax, NS, B3H 4J1, Canada