title: Changing the locking object inside @synchronized section
body: <p>Can I do any of the following? Will they properly lock/unlock the same object? Why or why not?  Assume there are many identical threads using global variable "obj", which was initialized before all threads started.</p>
  
  <p>1.</p>
  
  <pre><code>@synchronized(obj) {
      [obj release];
      obj = nil;
  }
  </code></pre>
  
  <p>2.</p>
  
  <pre><code>@synchronized(obj) {
      obj = [[NSObject new] autorelease];
  }
  </code></pre>