We have something I can't figure out happening on one of our servers. It's running 4.0.23
One of the InnoDB tables is locked even though we can't see any process that is even
could have locked it. SHOW OPEN TABLES doesn't show it as in use or locked. We've tried
of things to get access to it, short of bouncing the server, but it keeps saying it's
we try to acquire a lock on that table, the process list says "SYSTEM LOCK" and we get the
"Lock wait timeout exceeded; Try restarting transaction" message after 30 seconds.
I've tried this with AUTOCOMMIT on and off, with LOCK TABLES and with START TRANSACTION...
seems to help. Strangely, FLUSH TABLES WITH READ LOCK seems to succeed, but after
we still can't get a lock for this table.
I've never been able to see how we can find out which connection has the lock on a given
that's possible, I'd like to know that, too, so I could at least know how it got locked in
Could a misbehaving client do this in a way that would cause the lock to persist even
client has disconnected? If so, ugh.
Any help appreciated.