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Subject: Re: [OMPI devel] problem running mpirun and orted on same machine
From: Ralph Castain (rhc_at_[hidden])
Date: 2012-02-06 12:49:23

On Feb 6, 2012, at 10:35 AM, Maurice Feskanich wrote:

> Hi Ralph,
> Is it always the case that a proc launched local to mpirun uses mpirun as the daemon?

Yes - mpirun knows which procs are local and launches them. You can, however, tell mpirun -not- to use the local node for MPI procs by adding -no-use-local to the cmd line (or set the equiv mca param). Note that no MPI proc will then be launched on the node where mpirun resides if you set that flag.

> Our engine is not local to the host that mpirun is on, it just happens to send the task back to that same host, and the grid engine system handles all the process starting.

Guess I'm confused. If SGE is starting the MPI procs, then why are you starting orteds at all? What purpose can they serve if the orteds aren't starting the procs themselves?

> If it is the case, is there any particular flag or option I should be using with the orted on the local host to indicate that it is local?

No orted can be local to mpirun - it will confuse the system.

> Should I even be starting an orted in this case, and if not, how would I start the proc? Also, would it be safe to always decrease by one the maximum vpid used with the orteds for the other tasks?

You just need to accurately compute the number of orteds being launched. There is one per node, minus the node where mpirun is executing.

I'm willing to chat about this on the phone, if it would help. Contact me off-list if you want to do so.

> Thanks,
> Maury
> On 02/03/12 11:24, Ralph Castain wrote:
>> No brilliant suggestion - it sounds like your plugin isn't accurately computing the number of daemons. When a proc is launched local to mpirun, it uses mpirun as the daemon - it doesn't start another daemon on the same node. If your plugin is doing so, or you are computing an extra daemon vpid that doesn't truly exist, then you will have problems.
>> On Feb 3, 2012, at 11:27 AM, Maurice Feskanich wrote:
>>> Hi Folks,
>>> I'm having a problem with running mpirun when one of the tasks winds up running on the same machine as mpirun.
>>> A little background: our system uses a plugin to send tasks to grid engine. We are currently using version 1.3.4 (we are not able to move to a newer version because of the requirements of the tools that use our system.) Our code runs on Solaris (both Sparc and X86), and Linux.
>>> What we are seeing is that sometimes mpirun gets a segmentaion violation at line 342 of plm_base_launch_support.c:
>>> pdatorted[mev->sender.vpid]->state = ORTE_PROC_STATE_RUNNING;
>>> Investigation has found that mev->sender.vpid is a number that is one greater than the number of non-nil elements in the pdatorted array.
>>> Here is the dbx stacktrace:
>>> t_at_1 (l_at_1) program terminated by signal SEGV (no mapping at the fault address)
>>> Current function is process_orted_launch_report (optimized)
>>> 342 pdatorted[mev->sender.vpid]->state = ORTE_PROC_STATE_RUNNING;
>>> (dbx) where
>>> current thread: t_at_1
>>> =>[1] process_orted_launch_report(fd = ???, opal_event = ???, data = ???) (optimized), at 0xffffffff7f491e60 (line ~342) in "plm_base_launch_support.c"
>>> [2] event_process_active(base = ???) (optimized), at 0xffffffff7f241d04 (line ~651) in "event.c"
>>> [3] opal_event_base_loop(base = ???, flags = ???) (optimized), at 0xffffffff7f242178 (line ~823) in "event.c"
>>> [4] opal_event_loop(flags = ???) (optimized), at 0xffffffff7f241f98 (line ~730) in "event.c"
>>> [5] opal_progress() (optimized), at 0xffffffff7f21d484 (line ~189) in "opal_progress.c"
>>> [6] orte_plm_base_daemon_callback(num_daemons = ???) (optimized), at 0xffffffff7f492388 (line ~459) in "plm_base_launch_support.c" [7] orte_plm_dream_spawn(0x8f0ac, 0x478560, 0x47868c, 0x12c, 0xffffffff7d305198, 0x8a8c0000), at 0xffffffff7d304a5c
>>> [8] orterun(argc = 11, argv = 0xffffffff7fffede8), line 748 in "orterun.c"
>>> [9] main(argc = 11, argv = 0xffffffff7fffede8), line 13 in "main.c"
>>> The vpids we use when we start the orteds are 1-based, but the pdatorted array is zero-based.
>>> Any help anyone can provide would be very appreciated. Please don't hesitate to ask questions.
>>> Thanks,
>>> Maury Feskanich
>>> Oracle, Inc.
>>> _______________________________________________
>>> devel mailing list
>>> devel_at_[hidden]
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