Failed to create - mailbox is locked

[Bron Gondwana]

IOERROR: failed to create fastmail.com!user.REDACTED.#calendars (Mailbox is locked)

We get these occasionally, and I wondered why until just now, when I remembered...

The initial CREATE or RENAME lock.. it's a mboxname_lock EXCLUSIVE, and it's taken with nowait, and error if exists.  It needs to, because the source mailbox is locked, and you need to break a lock loop if you issued rename A => B and rename B => A in parallel.

So it was assumed as being not a problem, because you'd never try to create the same name twice concurrently.  The name didn't exist before, so nobody will be looking at it.

When I say "it was assumed", I mean that I assumed.  In 2009 some time.

But that's not true when you're autocreating the same name when you try to read something.  Anything.

In fact, the way that the parser works, you wind up doing it for any http request.  So you get a race between two processes, one loses, logs this.

We should probably fix this :)

Bron.



-- 
  Bron Gondwana
  brong at fastmail.fm