File Locking Question

alejandrina <>
14 Jul 2007 12:01:20 -0700

I am trying to use Java's FileLock class to synchronize writing to a
file **across machines**. The file resides on a file server. Under
Windows, it works perfectly (ie, only one machine at a time can gain
access, the others wait,no clobbered file, everything is written in
order). Under Linux (same code) the file gets clobbered. No exceptions
are thrown.

Can anyone offer suggestions??

Here is the critical code segment:

        //lock the file and wait till we can
        FileChannel channel = fos.getChannel();
        FileLock lock = null;
        try {
            while ((lock = channel.tryLock()) == null) {
                System.out.println (Utils.getHostname() + " Failed lock...wait");

            System.out.println (Utils.getHostname() + " Locked:" + lock);
            System.out.println (Utils.getHostname() + " Lock type is "+

            System.out.println (Utils.getHostname() + " Is lock valid: " +

         //write the title first if noone's done it
         //and they asked for one
         if (channel.size() <= 0 && bbTitle != null)
         channel.write (bbTitle);

         } catch (Exception e) {
         throw (e);
         } finally {
         if (lock != null) {
         System.out.println (Utils.getHostname() + " Releasing lock");

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