public class NativeFSLockFactory extends FSLockFactory
Implements 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 SimpleFSLockFactory
first and work around the one limitation that a lock file
could be left when the JVM exits abnormally.
The primary benefit of NativeFSLockFactory is
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 VerifyingLockFactory, LockVerifyServer and LockStressTest.
LockFactorylockDirlockPrefix| Constructor and Description |
|---|
NativeFSLockFactory()
Create a NativeFSLockFactory instance, with null (unset)
lock directory.
|
NativeFSLockFactory(File lockDir)
Create a NativeFSLockFactory instance, storing lock
files into the specified lockDir:
|
NativeFSLockFactory(String lockDirName)
Create a NativeFSLockFactory instance, storing lock
files into the specified lockDirName:
|
| Modifier and Type | Method and Description |
|---|---|
void |
clearLock(String lockName)
Attempt to clear (forcefully unlock and remove) the
specified lock.
|
Lock |
makeLock(String lockName)
Return a new Lock instance identified by lockName.
|
getLockDir, setLockDir, toStringgetLockPrefix, setLockPrefixpublic NativeFSLockFactory()
FSDirectory
subclass, the lock directory is automatically set to the
directory itself. Be sure to create one instance for each directory
your create!public NativeFSLockFactory(String lockDirName)
lockDirName - where lock files are created.public NativeFSLockFactory(File lockDir)
lockDir - where lock files are created.public Lock makeLock(String lockName)
LockFactorymakeLock in class LockFactorylockName - name of the lock to be created.public void clearLock(String lockName) throws IOException
LockFactoryclearLock in class LockFactorylockName - name of the lock to be cleared.IOExceptionCopyright © 2000-2014 Apache Software Foundation. All Rights Reserved.