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Re: MariaDB non-blocking with EPOLL


Dave C <dave.zap@xxxxxxxxx> writes:

> With you help I was able to get the whole thing working this afternoon,
> although I will need to spend a lot more time testing and checking I've
> caught all the traps.

Ok, great!

> The core application uses edge triggered epoll for the sake of efficiency
> and so far I have not found any problems running the queries now with the
> non-blocking API.

Yes, I agree edge-triggered is a good way, and it is supposed to work (and
if you should find something that does not, I'll fix it).

> At this point it's simple so I'm only checking POLLIN as that seems to work
> for the connect and query and fetch_row that I'm going.
> I guess the MYSQL_WAIT_TIMEOUT is not being passed because I've just not
> run in to that case yet, but will unset it as you mention before passing it
> to _cont()
> The timeout on epoll_wait() is set to 1 second, but we never reach that due
> the amount of traffic. One second is the max because we must service other
> things no later then that, for things such as automatically destroying non
> responsive sockets after 30 seconds, including the MariaDB ones. The case
> of queries that timeout can be handled in the same way, or else I can check
> for standard mysql error codes?

Yes, I think you can handle it the same way. It is probably safe to ignore
MYSQL_WAIT_TIMEOUT completely. Then the MYSQL_OPT_*_TIMEOUT options for
mysql_options() will do nothing, but if you handle non responsive sockets
differently anyway, that might be fine.

> Thanks again for your help. If I find anything weird I'll drop a post here,
> but more often then not the weirdness is on my side.
> One interesting side effect of passing 0 to _cont() functions was the
> multitude of segfaults I was getting on other random / unrelated functions
> I'll see If I can replicate that once I've bedded everything down.

 - Kristian.