public final class NativeFSLockFactory extends FSLockFactory
LockFactory using native OS file
locks. Note that because this LockFactory relies on
java.nio.* APIs for locking, any problems with those APIs
will cause locking to fail. Specifically, on certain NFS
environments the java.nio.* locks will fail (the lock can
incorrectly be double acquired) whereas
SimpleFSLockFactory worked perfectly in those same
environments. For NFS based access to an index, it's
recommended that you try
first and work around the one limitation that a lock file
could be left when the JVM exits abnormally.
The primary benefit of
that locks (not the lock file itsself) will be properly
removed (by the OS) if the JVM has an abnormal exit.
Note that, unlike
SimpleFSLockFactory, the existence of
leftover lock files in the filesystem is fine because the OS
will free the locks held against these files even though the
files still remain. Lucene will never actively remove the lock
files, so although you see them, the index may not be locked.
Special care needs to be taken if you change the locking implementation: First be certain that no writer is in fact writing to the index otherwise you can easily corrupt your index. Be sure to do the LockFactory change on all Lucene instances and clean up all leftover lock files before starting the new configuration for the first time. Different implementations can not work together!
If you suspect that this or any other LockFactory is
not working properly in your environment, you can easily
test it by using
This is a singleton, you have to use
|Modifier and Type||Field and Description|
|Modifier and Type||Method and Description|
Implement this method to obtain a lock for a FSDirectory instance.
public static final NativeFSLockFactory INSTANCE
protected Lock obtainFSLock(FSDirectory dir, String lockName) throws IOException
IOException- if the lock could not be obtained.
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