Name: jl125535 Date: 11/28/2001


java version "1.4.0-beta3"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.0-beta3-b84)
Java HotSpot(TM) Client VM (build 1.4.0-beta3-b84, mixed mode)


1. While attempting to acquire a lock on a text file using the following code,
an unxexpected error message occurs:

import java.io.*;
import java.nio.*;
import java.nio.channels.*;

class FileLockTest {

    public static void main(String args[]) throws Exception {
        RandomAccessFile raf = new RandomAccessFile("FileCopy.java", "rw");
        FileChannel channel = raf.getChannel();

        // FileLock lock = channel.lock(); // also fails with same message
        FileLock lock = channel.tryLock();

        System.out.println("File locked. Press any key to continue...");
        System.in.read();

        lock.release();
        channel.close();
    }
}

3. The following error message is generated:
Exception in thread "main" java.io.IOException: The parameter is incorrect
        at sun.nio.ch.FileChannelImpl.lock0(Native Method)
        at sun.nio.ch.FileChannelImpl.tryLock(FileChannelImpl.java:515)
        at java.nio.channels.FileChannel.tryLock(FileChannel.java:912)
        at FileLockTest.main(FileLockTest.java:12)

4. This sample program works on Windows 2000 with both lock() and tryLock().

5. On Solaris 8, the sample program works with tryLock(), but lock() results
   in the following error message:
Exception in thread "main" java.io.IOException: No record locks available
        at sun.nio.ch.FileChannelImpl.lock0(Native Method)
        at sun.nio.ch.FileChannelImpl.lock(FileChannelImpl.java:477)
        at java.nio.channels.FileChannel.lock(FileChannel.java:812)
        at FileLockTest.main(FileLockTest.java:11)

6. If the behaviors in (3) and (5) are expected (see the customer workaround),
perhaps more appropriate error messages or a site for common compatibility
issues would help. The current documentation

http://java.sun.com/j2se/1.4/docs/api/java/nio/channels/FileChannel.html#lock()

talks about platform dependencies. Specific information for common platforms
would be a nice addition.

(Review ID: 135868)
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