migrate GlusterFS to use libepoll-shim

[Claude Steiner]

Hi there,

As you might know, GlusterFS is suffering from growing memory consumption
(both on server/client). As many memory leaks seem to be fixed in the
latest 8.4 version for Liunux (that Daniel Morante was so kind to prepare
an update of the port to test this), this seems not to help on FreeBSD. It
seems like there is a "deeper" problem of how GlusterFS is using the
FreeBSD OS.

Daniel Morante (maintainer of glusterfs port) has a suspicion that it could
be because of the way the fallback poll (because epoll from Linux is
missing on freebsd) was included to be used on FreeBSD. So he started to
try to use devel/libepoll-shim as a substitute, but run into some problems.

I wanted to ask you, if somebody of the FreeBSD team with experience in
using devel/libepoll-shim (and porting applications to use it on freebsd)
could take a look into his issue, as I think having a full working cluster
filesystem on FreeBSD is quite an important thing that right now is missing
(due to the memory bug of glusterfs), and we should all join efforts on
having this eventually resolved once and forever. Feel free to let me know
if I can be of any further help, but my deeper understanding of the FreeBSD
OS/kernel stuff is very limited, but I can run some tests and do some
logging if it would help.

You can find all problem description and what we so far have done about
that glusterfs trouble here:
https://github.com/gluster/glusterfs/issues/2173

Best regards and greetings,

Claude Steiner