java.util.logging.FileHandler and multithreading

Question

The FileHandler class from java.util.logging implements some sort of locking mechanism for the file it is writing to. However i found that there a .lck files lying around in the filesystem after an application is finished. Is there a way to customize the behaviour of the FileHandler class with respect to .lck files or the whole locking mechanism?

EDIT: It seems that when I close the FileHandler object the .lck files vanish. Is this wanted behaviour? I somehow expected that the FileHandler's close method should be called automatically...

Answer 1

you can use the function System.addShutdownHookFinalizer(Runnable r) that activate thread that is job is to close everything that is not closed. so you will close the FileHandler and the .lck file will be vanish

Answer 2

It seems that when I close the FileHandler object the .lck files vanish. Is this wanted behaviour? I somehow expected that the FileHandler's close method should be called automatically

The LogManager has a shutdown hook that will close the FileHandler if it is still attached to the logger at the time of shutdown. The problem is that the loggers can be subject to garbage collection. If that happens then the FileHandler is never closed. This is covered in the following bugs:

1. JDK-8060132 Handlers configured on abstract nodes in logging.properties are not always properly closed.
2. JDK-6274920: JDK logger holds strong reference to java.util.logging.Logger instances.

Keep a strong reference to your loggers so they are not garbage collected.