memcached crashing

Jon Valvatne jon@valvatne.com
Wed, 30 Jun 2004 05:59:50 +0200


Hello,

I've been using memcached to add some caching to a production system to
speed things up. Everything worked smoothly on my test box, but I ran
into nothing but problems when trying to go live with the changes:
Memcached would just die randomly, without any error message whatsoever,
within minutes of startup. And even while it was running and accepting
some connections, other connections appeared to be randomly refused.

The only difference between the test box and the production system is
that one is running Fedora Core 2, and the other Redhat 9. Before I try
to debug the situation more, I would like to ask: Does anyone here have
any experience running memcached with Redhat 9? There's obviously no
epoll support, so I compiled the latest libevent with --with-rtsig, and
I'm assuming that's what memcached is using. Is this just inherently
buggy, or so poor-performing that my system with about a hundred
connections and several operations per second will cause the problem I'm
seeing?

One thing that worried me were the test results when compiling libevent:

Running tests:
KQUEUE
Skipping test
POLL
 test-eof: OKAY
 test-weof: OKAY
 test-time: OKAY
 regress: FAILED
SELECT
 test-eof: OKAY
 test-weof: OKAY
 test-time: OKAY
 regress: FAILED
RTSIG
 test-eof: OKAY
 test-weof: OKAY
 test-time: OKAY
 regress: FAILED
EPOLL
Skipping test

What are these regress tests, and what would cause them to fail?

By the way: Is there any way to ask memcached or libevent which polling
mechanism is being used?

Thanks in advance,

Jon Valvatne