How can I clear a transaction deadlock?

Using 'show engine innodb status' I see that wordpress has two deadlocks... Suggestions on how to resolve this?

We were seeing Java hibernate issues causing stuck locks. We found the locks by combing trough the output from:

show engine innodb status;

This spits out a crap-ton of information. The relevant section is in the TRANSACTIONS section. In your output the relevant problem seems to be:

3 lock struct(s), heap size 1248, 2 row lock(s)
MySQL thread id 12505095, query id 909492789 juno....edu 129.....54 

For us it was the # lock struct(s) that indicated a stuck lock. To kill it you need to execute by using the "thread id #" specified -- in this case:

kill 12505095

This worked on AWS MySQL RDS as well as local MySQL.

In our TRANSACTIONS section we also see the following:

---TRANSACTION 644793773, ACTIVE 21 sec
2 lock struct(s), heap size 360, 1 row lock(s)
MySQL thread id 217, OS thread handle 0x2aef097700, query id 1177 1.3.5.7 mpsp cleaning up

We look for both the 2 lock struct(s) and the ACTIVE 21 sec messages.

Given some 'innodb status' output like this:

---TRANSACTION 0 0, not started, process no 1024, OS thread id 140386055603968
MySQL thread id 197, query id 771 localhost marc
show innodb status

you'd want to do

KILL QUERY 771

to kill one of the two queries that are deadlocked. That'll kill the query, but leave the connection open. if you want to kill the connection, then you'd do KILL 197.

I know this is old, but typically when you see something like this it's because a deadlock occurred and the app that triggered the deadlock has long since moved on -- the victim of the deadlock got warned and either failed, or logged an error or retried, and either way has moved on to other productive things. You usually don't need to do anything other than look into the cause of the deadlock and try and avoid future deadlocks, if you're writing the software. If you're just using the software (e.g. Wordpress if you don't work at Wordpress), you could report the deadlock as a possible bug.