Re: GRs and request completion

Rajeev Thakur (thakur@mcs.anl.gov)
Tue, 6 May 1997 17:25:19 -0500

> Dick raised a second point that once you call MPI_REQUEST_FREE you no
> longer have a valid handle to use in a call to MPI_GREQUEST_COMPLETE.
> I think this is a real problem and have yet to come up with a good
> solution. Here is what I have thought about.

If the library that implements the generalized request maintains its
own copy of the request handle, and not a pointer to the application's
handle, this should not be a problem. For example, an application
program calls MPI_REQUEST_FREE, which results in the application's
request handle being set to null. MPI_GREQUEST_COMPLETE will be called
by some other entity---the library that implements the GR. The
library's handle will not be set to null. It can call
MPI_GREQUEST_COMPLETE with this handle, only after which will the free_fn
be called and the request really be freed.

Rajeev