FULL PRODUCT VERSION :
java version "1.5.0"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0-b64)
Java HotSpot(TM) Client VM (build 1.5.0-b64, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows XP [Version 5.1.2600]

A DESCRIPTION OF THE PROBLEM :
If a thread is interrupted while it is blocked in FileChannel.lock() that method might return null instead of a valid FileLock object or throwing a exception.

  From the JDK source it seems this can happen because begin() in AbstractInterruptibleChannel sets open to false if the thread is interrupted. In FileChannelImpl.lock() (line 781) null is returned if isOpen() returns false.

According to the JDK docs FileChannel.lock() should throw a FileLockInterruptionException in this case and not return null.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Since this bug involves interrupting a thread at exactly the right time it is not easy to reproduce. It sometimes is reproducable on my machine by executing the attached sample code. If the bug was reproduced it will output "Lock is null!".

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
FileChannel.lock() should throw a FileLockInterruptionException.
ACTUAL -
FileChannel.lock() returns null.

REPRODUCIBILITY :
This bug can be reproduced occasionally.

---------- BEGIN SOURCE ----------
import java.io.*;
import java.nio.channels.*;

public class FileChannelTest
{
    private static Thread createLockThread(final File file)
    {
        return new Thread() {
            public void run() {
                try {
                    FileOutputStream out = new FileOutputStream(file);
                    FileChannel channel = out.getChannel();
                    FileLock lock = channel.lock();
                    
                    if(lock == null) {
                        System.out.println("Lock is null!");
                    }
                    
                    Thread.sleep(5000);
                    lock.release();
                    channel.close();
                }
                catch(InterruptedException ex) {
                }
                catch(Throwable t) {
                    t.printStackTrace();
                }
            }
        };
    }
    
    public static void main(String args[])
        throws Exception
    {
        File file = File.createTempFile("test", "");
        file.deleteOnExit();
        
        Thread t1 = createLockThread(file);
        Thread t2 = createLockThread(file);

        t1.start();
        Thread.sleep(100);
        t2.start();


        t2.interrupt();
    }
}

---------- END SOURCE ----------
###@###.### 2004-12-16 19:19:51 GMT