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Subject: Re: [OMPI users] MPI process dies with a route error when using dynamic process calls to connect more than 2 clients to a server with InfiniBand
From: Philippe (philmpi_at_[hidden])
Date: 2010-07-18 18:09:35


Ralph,

thanks for investigating.

I've applied the two patches you mentioned earlier and ran with the
ompi server. Although i was able to runn our standalone test, when I
integrated the changes to our code, the processes entered a crazy loop
and allocated all the memory available when calling MPI_Port_Connect.
I was not able to identify why it works standalone but not integrated
with our code. If I found why, I'll let your know.

looking forward to your findings. We'll be happy to test any patches
if you have some!

p.

On Sat, Jul 17, 2010 at 9:47 PM, Ralph Castain <rhc_at_[hidden]> wrote:
> Okay, I can reproduce this problem. Frankly, I don't think this ever worked with OMPI, and I'm not sure how the choice of BTL makes a difference.
>
> The program is crashing in the communicator definition, which involves a communication over our internal out-of-band messaging system. That system has zero connection to any BTL, so it should crash either way.
>
> Regardless, I will play with this a little as time allows. Thanks for the reproducer!
>
>
> On Jun 25, 2010, at 7:23 AM, Philippe wrote:
>
>> Hi,
>>
>> I'm trying to run a test program which consists of a server creating a
>> port using MPI_Open_port and N clients using MPI_Comm_connect to
>> connect to the server.
>>
>> I'm able to do so with 1 server and 2 clients, but with 1 server + 3
>> clients, I get the following error message:
>>
>>   [node003:32274] [[37084,0],0]:route_callback tried routing message
>> from [[37084,1],0] to [[40912,1],0]:102, can't find route
>>
>> This is only happening with the openib BTL. With tcp BTL it works
>> perfectly fine (ofud also works as a matter of fact...). This has been
>> tested on two completely different clusters, with identical results.
>> In either cases, the IB frabic works normally.
>>
>> Any help would be greatly appreciated! Several people in my team
>> looked at the problem. Google and the mailing list archive did not
>> provide any clue. I believe that from an MPI standpoint, my test
>> program is valid (and it works with TCP, which make me feel better
>> about the sequence of MPI calls)
>>
>> Regards,
>> Philippe.
>>
>>
>>
>> Background:
>>
>> I intend to use openMPI to transport data inside a much larger
>> application. Because of that, I cannot used mpiexec. Each process is
>> started by our own "job management" and use a name server to find
>> about each others. Once all the clients are connected, I would like
>> the server to do MPI_Recv to get the data from all the client. I dont
>> care about the order or which client are sending data, as long as I
>> can receive it with on call. Do do that, the clients and the server
>> are going through a series of Comm_accept/Conn_connect/Intercomm_merge
>> so that at the end, all the clients and the server are inside the same
>> intracomm.
>>
>> Steps:
>>
>> I have a sample program that show the issue. I tried to make it as
>> short as possible. It needs to be executed on a shared file system
>> like NFS because the server write the port info to a file that the
>> client will read. To reproduce the issue, the following steps should
>> be performed:
>>
>> 0. compile the test with "mpicc -o ben12 ben12.c"
>> 1. ssh to the machine that will be the server
>> 2. run ./ben12 3 1
>> 3. ssh to the machine that will be the client #1
>> 4. run ./ben12 3 0
>> 5. repeat step 3-4 for client #2 and #3
>>
>> the server accept the connection from client #1 and merge it in a new
>> intracomm. It then accept connection from client #2 and merge it. when
>> the client #3 arrives, the server accept the connection, but that
>> cause client #1 and #2 to die with the error above (see the complete
>> trace in the tarball).
>>
>> The exact steps are:
>>
>>     - server open port
>>     - server does accept
>>     - client #1 does connect
>>     - server and client #1 do merge
>>     - server does accept
>>     - client #2 does connect
>>     - server, client #1 and client #2 do merge
>>     - server does accept
>>     - client #3 does connect
>>     - server, client #1, client #2 and client #3 do merge
>>
>>
>> My infiniband network works normally with other test programs or
>> applications (MPI or others like Verbs).
>>
>> Info about my setup:
>>
>>    openMPI version = 1.4.1 (I also tried 1.4.2, nightly snapshot of
>> 1.4.3, nightly snapshot of 1.5 --- all show the same error)
>>    config.log in the tarball
>>    "ompi_info --all" in the tarball
>>    OFED version = 1.3 installed from RHEL 5.3
>>    Distro = RedHat Entreprise Linux 5.3
>>    Kernel = 2.6.18-128.4.1.el5 x86_64
>>    subnet manager = built-in SM from the cisco/topspin switch
>>    output of ibv_devinfo included in the tarball (there are no "bad" nodes)
>>    "ulimit -l" says "unlimited"
>>
>> The tarball contains:
>>
>>   - ben12.c: my test program showing the behavior
>>   - config.log / config.out / make.out / make-install.out /
>> ifconfig.txt / ibv-devinfo.txt / ompi_info.txt
>>   - trace-tcp.txt: output of the server and each client when it works
>> with TCP (I added "btl = tcp,self" in ~/.openmpi/mca-params.conf)
>>   - trace-ib.txt: output of the server and each client when it fails
>> with IB (I added "btl = openib,self" in ~/.openmpi/mca-params.conf)
>>
>> I hope I provided enough info for somebody to reproduce the problem...
>> <ompi-output.tar.bz2>_______________________________________________
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>> users_at_[hidden]
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>
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