procmail unique() file bug

Hi,

>From time to time, I spot a very strange behaviour from procmail.

In the mail spool dir it start to populate it with files in the format
_<random>.<hostname> file.

Usually it gets up to a few hundred thousands of empty files that bogs
down the server.  It usually stops when VFS max file limit is reach in
the kernel.

This file is created by the unique() function as far as I can tell and
it is used to be renamed to be the lock file.  Something is preventing
it from work as expected and this files are never removed.

This happens in a 1, 2 or 3 months interval, so the next time will take
a while as it just happened today.

This is a Linux 2.6.11 SMP machine.
procmail is 3.22 using traditional MBOX files in /var/spool/mail.
procmail is called from sendmail 8.13.6.
The FS is a ext3 one and no NFS is used.


Is this bug familiar?  Is there an easy way to debug/prevent this?



- Raul Dias