Re: Findbugs and locks?

From:
Knute Johnson <nospam@rabbitbrush.frazmtn.com>
Newsgroups:
comp.lang.java.help
Date:
Wed, 30 Jul 2008 22:49:49 -0700
Message-ID:
<4891527a$0$4018$b9f67a60@news.newsdemon.com>
Daniel Pitts wrote:

Knute Johnson wrote:

Ah but look at what does!

  static void method(int n) throws IOException {

// WriteLock lock = lockArray[n].writeLock();
// lock.lock();
      lockArray[n].writeLock().lock();
    try {
      // do some disk I/O
    } finally {
// lock.unlock();
        lockArray[n].writeLock().unlock();
    }
  }

I think it is a bug in findbugs. I think I'll drop them a line.


I don't think its a bug in findbugs.
The problem is that lockArray[n] might through an exception in the
finally if the lockArray changes size. lockArray[n] might also be
assigned a null at some point, so lockArray[n].writeLock() could through
an NPE.

I think a better approach would be to have method take a Lock rather
than an index into an array.

Hope this helps,
Daniel.


If the lock throws an exception, how can it be locked?

--

Knute Johnson
email s/nospam/knute2008/

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