Re: Findbugs and locks?

Lew <com.lewscanon@lew>
Wed, 30 Jul 2008 09:17:03 -0400
Jeff Higgins wrote:

    if (n < lockArray.length) {
      ReentrantReadWriteLock rrwl = lockArray[n];
      WriteLock lock = rrwl.writeLock();
      try {
        // do some disk I/O
      } finally {

Is there a chance that lock.lock() would fail?

If so, would lock.unlock() cause any harm?

The usual pattern for resource acquisition and release with try-finally is

  // break flow on acquire() failure

That way the release() only occurs if the acquire() succeeds. Moving the
acquire() into the try{} means that the release() will occur even if acquire()
fails. This is how Knute coded it, and I don't see why his way caused a warning.

I would be more comfortable if Knute's way didn't cause any warnings, because
I don't understand it either. However, I'm unfamiliar with Findbugs (although
many recommend it very highly).


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