harlowja / fasteners

A python package that provides useful locks.
Apache License 2.0
246 stars 45 forks source link

Close fd when acquire fails. #39

Open terrifiedquack opened 5 years ago

terrifiedquack commented 5 years ago

I ran into an interesting corner case the other day: The lockfile's fd is opened when attempting to acquire the lock, and remains open until the lock is released. This means that in cases where the lock is not successfully acquired before the objects go away, a ResourceWarning of an unclosed fd is printed. This can also cause unclosed fds to accumulate, or even cause a process to run out of fds.

This came up for me when attempting to clean up an old tmp/lockdir, when attempting to acquire many locks but immediately give up when unsuccessful, and then remove them when successful.

This closes the file when acquire fails to acquire the lock for any reason.