[concurrency-interest] New version of Java Concurrent Animated

Nathan Reynolds nathan.reynolds at oracle.com
Wed Apr 17 02:34:30 EDT 2013


Nice animation!  I noticed a couple of problems.

The ConcurrentHashMap demo fails to draw the threads if you keep hitting 
putIfAbsent.  The threads are drawn beyond the bottom.

If I remember right ReentrantReadWriteLock gives priority to writer 
threads.  If that is the case then the ReadWriteLock demo is not quite 
right.

Consider this scenario.

 1. Thread #1 calls writeLock().lock() and enters the critical region.
 2. Thread #2 calls readLock().lock() and blocks.
 3. Thread #3 calls readLock().lock() and blocks.
 4. Thread #4 calls readLock().lock() and blocks.
 5. Thread #5 calls readLock().lock() and blocks.
 6. Thread #6 calls writeLock().lock() and blocks.
 7. Thread #1 releases the lock.
 8. If writer threads are given priority, then Thread #6 should enter
    the critical region.

In the demo, threads #2 to #5 are given the lock in step 8.

Nathan Reynolds 
<http://psr.us.oracle.com/wiki/index.php/User:Nathan_Reynolds> | 
Architect | 602.333.9091
Oracle PSR Engineering <http://psr.us.oracle.com/> | Server Technology
On 4/16/2013 6:02 PM, Victor Grazi wrote:
> Hi, just a quick note to let everyone know there is a new version of 
> Java Concurrent Animated on SourceForge.
>
> Some of the new features:
> * A new animation showing good old synchronized/wait/notify. Kind of 
> surprising when you see it in action.
> * Thread states are now color coded, and includes a novel state 
> diagram kind courtesy of Dr. Heinz Kabutz and his Concurrency 
> Specialist Training 
> <http://www.javaspecialists.eu/courses/concurrency.jsp> course.
>
> Check it out!
> Thanks
> Victor Grazi
>
>
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