Bugs item #1512163, was opened at 2006-06-25 11:38 Message generated for change (Comment added) made by akuchling You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1512163&group_id=5470
Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: Python Library Group: Python 2.5 Status: Open Resolution: None Priority: 5 Submitted By: David Watson (baikie) Assigned to: A.M. Kuchling (akuchling) Summary: mailbox (2.5b1): locking doesn't work (esp. on FreeBSD) Initial Comment: fcntl/flock() locking of mailboxes is actually disabled due to a typo: --- mailbox.py.orig +++ mailbox.py @@ -15,7 +15,7 @@ import rfc822 import StringIO try: - import fnctl + import fcntl except ImportError: fcntl = None However, once enabled, it doesn't work on FreeBSD - the lock() method always raises ExternalClashError (tested on 5.3). This is because flock(), lockf() and fcntl locking share the same underlying mechanism on this system (and probably others), and so the second lock can never be acquired. ---------------------------------------------------------------------- >Comment By: A.M. Kuchling (akuchling) Date: 2006-06-26 08:56 Message: Logged In: YES user_id=11375 Interesting. The man page for flock() on my Linux system says of flock() in a certain version: "This yields true BSD semantics: there is no interaction between the types of lock placed by flock(2) and fcntl(2), and flock(2) does not detect deadlock." Apparently this is out of date, and placing two locks is harmful. I think it's best to just use one set of locking primitives, and that one should be lockf(); the flock() calls should be removed. ---------------------------------------------------------------------- Comment By: Neal Norwitz (nnorwitz) Date: 2006-06-25 15:52 Message: Logged In: YES user_id=33168 Andrew, are you helping maintain this module? David is correct that fcntl is mispelled in current svn. Not sure what to do about the locking issue. David, would it be possible for you to work on a patch to correct this problem? I'm not sure if any developer has access to a FreeBSD box similar to yours. (There are a couple that use FreeBSD though.) It would be great to come up with tests for this if the current ones don't stress this situation. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1512163&group_id=5470 _______________________________________________ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com