On May 28, 2014, at 1:18 AM, Gilles Gouaillardet <gilles.gouaillar...@gmail.com> wrote:
> i finally got it :-) Hooray! Thanks for digging deeper. > > /* i previously got it "almost" right ... */ > > here is what happens on job 2 (with trunk) : > MPI_Intercomm_create calls ompi_comm_get_rprocs that calls ompi_proc_unpack > => ompi_proc_unpack store job 3 info into opal_dstore_peer > > > then ompi_comm_get_rprocs calls ompi_proc_set_locality(job 3) > => ompi_proc_set_locality fetch information job 3 info from > opal_dstore_internal (not found) and then opal_dstore_nonpeer (not found > again) and then fails. > this is just the consequence of ompi_proc_unpack stored job 3 info in > opal_dstore_peer and not in opal_dstore_nonpeer > > i do not understand which of opal_dstore_peer and opal_dstore_nonpeer should > be used Neither do I, frankly - all I can do is hope that someone actually uses the requested multi-store capability as it definitely makes it harder to know what should be going where... > and when, so i wrote a defensive patch (fetch both opal_dstore_nonpeer and > then opal_dstore_peer if not previously found). > > please someone review this and comment/fix it if needed > (for example, store in opal_dstore_nonpeer instead of opal_dstore_peer > *or* > fetch in opal_dstore_peer instead of opal_dstore_nonpeer > and/or something else ) It looks fine as written - again, thanks for finding it. > > and then, locality is correctly set, coll ml receives correct information and > this does not > hang any more if mpirun is invoked without --mca coll ^ml and on a single > node single socket VM) > > bottom line, job 2 *did* receive information of job 3 but failed to > store/fetch it in the right opal_store ! > > v1.8 is unaffected since there is only one dstore > > Cheers, > > Gilles > > > On Wed, May 28, 2014 at 4:51 AM, Ralph Castain <r...@open-mpi.org> wrote: > Hmmm...I did some digging, and the best I can tell is that root cause is that > the second job ("b" in the test program) is never actually calling > connect_accept! This looks like a change may have occurred in > Intercomm_create that is causing it to not recognize the need to do so. > > Anyone confirm that diagnosis? > > FWIW: job 1 clearly receives and has all the required info in the correct > places - it is ready to provide it to job 2, if/when job 2 actually calls > connect_accept. > > On May 27, 2014, at 10:13 AM, Ralph Castain <r...@open-mpi.org> wrote: > > > Hi Gilles > > > > I concur on the typo and fixed it - thanks for catching it. I'll have to > > look into the problem you reported as it has been fixed in the past, and > > was working last I checked it. The info required for this 3-way > > connect/accept is supposed to be in the modex provided by the common > > communicator. > > > > On May 27, 2014, at 3:51 AM, Gilles Gouaillardet > > <gilles.gouaillar...@gmail.com> wrote: > > > >> Folks, > >> > >> while debugging the dynamic/intercomm_create from the ibm test suite, i > >> found something odd. > >> > >> i ran *without* any batch manager on a VM (one socket and four cpus) > >> mpirun -np 1 ./dynamic/intercomm_create > >> > >> it hangs by default > >> it works with --mca coll ^ml > >> > >> basically : > >> - task 0 spawns task 1 > >> - task 0 spawns task 2 > >> - a communicator is created for the 3 tasks via MPI_Intercomm_create() > >> > >> MPI_Intercomm_create() calls ompi_comm_get_rprocs() which calls > >> ompi_proc_set_locality() > >> > >> then, on task 1, ompi_proc_set_locality() calls > >> opal_dstore.fetch(opal_dstore_internal, "task 2"->proc_name, ...) which > >> fails and this is OK > >> then > >> opal_dstore_fetch(opal_dstore_nonpeer, "task 2"->proc_name, ...) which > >> fails and this is *not* OK > >> > >> /* on task 2, the first fetch for "task 1" fails but the second success */ > >> > >> my analysis is that when task 2 was created, it updated its > >> opal_dstore_nonpeer with info from "task 1" which was previously spawned > >> by task 0. > >> when task 1 was spawned, task 2 did not exist yet and hence > >> opal_dstore_nonpeer contains no reference to task 2. > >> but when task 2 was spawned, opal_dstore_nonpeer of task 1 has not been > >> updated, hence the failure > >> > >> (on task 1, proc_flags of task 2 has incorrect locality, this likely > >> confuses coll ml and hang the test) > >> > >> should task1 have received new information when task 2 was spawned ? > >> shoud task2 have sent information to task1 when it was spawned ? > >> should task1 have (tried to) get fresh information before invoking > >> MPI_Intercomm_create() ? > >> > >> incidentally, i found ompi_proc_set_locality calls opal_dstore.store with > >> identifier &proc (the argument is &proc->proc_name everywhere else, so this > >> is likely a bug/typo. the attached patch fixes this. > >> > >> Thanks in advance for your feedback, > >> > >> Gilles > >> <proc.patch>_______________________________________________ > >> devel mailing list > >> de...@open-mpi.org > >> Subscription: http://www.open-mpi.org/mailman/listinfo.cgi/devel > >> Link to this post: > >> http://www.open-mpi.org/community/lists/devel/2014/05/14848.php > > > > _______________________________________________ > devel mailing list > de...@open-mpi.org > Subscription: http://www.open-mpi.org/mailman/listinfo.cgi/devel > Link to this post: > http://www.open-mpi.org/community/lists/devel/2014/05/14861.php > > <proc.patch>_______________________________________________ > devel mailing list > de...@open-mpi.org > Subscription: http://www.open-mpi.org/mailman/listinfo.cgi/devel > Link to this post: > http://www.open-mpi.org/community/lists/devel/2014/05/14882.php