Comment by seppo0010

Last time I check, multi-process byte-range file locking was a mess. I'm surprised by your statement about BerkeleyDB, because as far as I can tell it simply cannot be safely implemented.

This blog post (2010) explains what the status is http://0pointer.de/blog/projects/locking.html

If something has changed since then (or that article is incorrect), please let me know.