Same issue overhere.

See line 64 of lib/delayed/command.rb. Looks like it's trying to reconnect.

When exactly do you have a problem? I tried restarting my app after launching delayed_job, and that did not seem to cause any problems. Delayed jobs still get run.

When the MySQL server times the connection out, as per the MySQL server's configured wait_timeout setting.

Doesn't DJ continuously poll the MySQL server? Why would it time out?

Aha! Found it. The application uses two databases (on two different servers). DJ isn't being timed out by the server on which the delayed_jobs table exists; but one of the delayed jobs accesses a legacy database, on another server, and that's where the timeout occurs.

Sounds like this isn't necessarily a dj issue. Reopen if I'm wrong

what's the workaround?

I had this problem too because our delayed_job table is in a different database than our app. For those looking, here is my simple fix: http://github.com/bracken/delayed_job/commit/b73a7e561b89fc09ae77bb9c1cfc680062867e19
You could do the same thing in your custom daemons so that you can still use the main delayed_job branch.

For those still having this issue, make sure you try this first: http://guides.rubyonrails.org/2_3_release_notes.html#reconnecting-mysql-connections

Bracken's take on the issue makes the world of sense. Our problem is also from using multiple databases, where the jobs aren't stored in the database that the in-job code interacts with.