Now that readers are read-only, we no longer need to store lock files
in a different global lock directory than the index directory. This
has been a source of confusion and caused problems to users in the
Furthermore, once the write lock is stored in the index directory, it
no longer needs the big digest prefix that was previously required
to make sure lock files in the global lock directory, from different
indexes, did not conflict.
This way, all files related to an index will appear in a single
directory. And you can easily list that directory to see if a
"write.lock" is present to check whether a writer is open on the
Note that this change just affects how FSDirectory creates its default
lockFactory if no lockFactory was specified. It is still possible
(just no longer the default) to pick a different directory to store
your lock files by pre-instantiating your own LockFactory.
As part of this I would like to remove LOCK_DIR and the no-argument
constructor, in SimpleFSLockFactory and NativeFSLockFactory. I don't
think we should have the notion of a global default lock directory
anymore. This is actually an API change. However, neither
SimpleFSLockFactory nor NativeFSLockFactory haver been released yet,
so I think this API removal is allowed?
Finally I want to deprecate (but not yet remove, because this has been
in the API for many releases) the static LOCK_DIR that's in
FSDirectory. But it's now entirely unused.
See here for discussion leading to this: