Hangs on .lck files

[ArchReplicator]

Sometimes I see a hang during launch, and afterwards there are several files left over in the minecraft base dir with zero bytes and a .lck extension.  Sounds to me like something is getting a lock and not releasing it, or perhaps two things are getting several locks and they're not following the same sequence.  How would you go about tracking down a problem like this?  Running with ~60 mods, no idea if it's FML, one or more mods, or minecraft itself which is stuck holding the lock.  Could even be the launcher, I'm using MultiMC.

[ArchReplicator]

Sometimes I see a hang during launch, and afterwards there are several files left over in the minecraft base dir with zero bytes and a .lck extension.  Sounds to me like something is getting a lock and not releasing it, or perhaps two things are getting several locks and they're not following the same sequence.  How would you go about tracking down a problem like this?  Running with ~60 mods, no idea if it's FML, one or more mods, or minecraft itself which is stuck holding the lock.  Could even be the launcher, I'm using MultiMC.

[ArchReplicator]

Still seeing this hang randomly.  When it happens, there are .lck files hanging out for client log, server log, loader log, and something with ID Resolver.  If I re-launch with the lck files still out there, it hangs again.  Deleting the lck files lets it complete, but ID Resolver asks about the previously resolved conflicts.

 

Any ideas on how to find out what is leaving these lock files around, and what's getting stuck on them?