Re: [Starpu-devel] Assert : Number of copy requests left is not zero

[Samuel Thibault <samuel.thibault@ens-lyon.org>]

Xavier Lacoste, le Tue 04 Nov 2014 10:49:52 +0100, a écrit :
> >> [starpu][_starpu_mpi_early_data_check_termination][assert failure] 
> >> Number of copy requests left is not zero
> >> 
> >> Have you get an idea of what could cause this assert ?
> > 
> > I have added a note in the message: did you forget to post a receive
> > corresponding to a send?
> 
> Hmm I'll have a look at it.
> Can it be that I flush a data earlier than it should be ?

Ah, I'm realizing: you are not using starpu_mpi_send, starpu_mpi_recv
and alike explicitly, and always rely on the communications implicitly
generated by starpu_mpi_task_insert?

Normally, if all MPI nodes are doing exactly the same submission loop,
flushing data earlier is not a problem: the node needing it later will
receive it again, and the node owning it will know that the node needing
it later will need it, and thus sending it again.  Perhaps there is a
bug in StarPU-MPI, but we already test this scenario, so I'd rather
first make sure that the application is really running the same
submission loop first (perhaps you have made mistakes while pruning the
submission, and thus the node owning the data doesn't know it has to
send it again, or conversely).

Samuel