Spread 4.0.0 epoll/poll Patch
John Robinson from Vertica Systems posted a patch to the
Spread-users mailing list for converting the Spread client library
to use poll instead of
select. I went ahead and modified the
patch to enable the use of poll only when
HAVE_POLL is defined instead of removing the original
select code altogeher.
In addition, I modified the Spread events interface to
use epoll on Linux when
HAVE_EPOLL is defined. This change can improve the
performance of a Spread daemon when it is serving hundreds of
client connections.
To enable the poll patch to sp.c, configure with:
To enable the the epoll patch to events.c configure with:
To enable both configure with:
The epoll patch processes
high/medium and low priority events differently than the original
code, which may have adverse consequences. For each priority
level, if at least one ready event of a higher priority was processed,
then only one event of the current priority level is processed.
Otherwise, all ready events of the current priority level are
processed.
Also, the patch's simple hash into
epoll_event_map assumes file descriptor values are
assigned in sequence. So use it at your own risk. It's intended
only for the case where your Spread daemons are serving a lot of
connections and you may benefit from avoiding
select plus linear search.
| Patch File | Comment |
|---|---|
| spread-4.0.0-poll-epoll.patch | Even though it has been tested, this patch is highly experimental and not polished final code. It's really a quick and dirty hack. Use it at your own risk. This patch is constantly evolving and may result in an all-out rewrite of the spread event handling system. |