On 1/20/2012 1:06 PM, Timo Sirainen wrote:
Hmh. Still doesn't work 100%:
auth-worker(28788): Error: mysql: Query failed, retrying: MySQL
server has gone away (idled for 181 secs) auth-worker(7413): Error:
mysql: Query failed, retrying: MySQL server has gone away (idled for
298 secs)
I'm not really sure why it's not killing itself after 60 seconds of
idling. Probably related to how mysql code tracks idle time and how
idle_kill tracks it.. Anyway, those errors are much more rare now.
The mysql server starts tracking idle time as beginning after the last
network communication with the client. So presumably if the auth worker
gets marked as not idle by anything not involving interaction with the
mysql server, they could get out of sync.
Before you posted a potential fix to the idle timeout, I was looking at
other possible ways to resolve the issue. Currently, an authentication
request is tried exactly twice -- one initial try, and one retry.
Looking at driver-sqlpool.c:
if (result->failed_try_retry && !request->retried) {
Currently, retried is a boolean. What if retried was an integer instead,
and a new configuration variable allowed you to specify how many times
an authentication attempt should be retried? The default could be 2,
which would result in exactly the same behavior. But then you could set
it to 3 or 4 to prevent a request from hitting a timed out connection
twice and failing completely.
Ideally, a better fix would be for the client not to consider a "MySQL
server has gone away" return as a failure, but instead immediately
reconnect and try again without marking it as a retry. However, from
reviewing the code, that would be a much more difficult and invasive
change. Changing the existing retried variable to an integer count
rather than a boolean is pretty simple.
--
Paul B. Henson | (909) 979-6361 | http://www.csupomona.edu/~henson/
Operating Systems and Network Analyst | hen...@csupomona.edu
California State Polytechnic University | Pomona CA 91768
