Re: Code Review 7051516: ThreadLocalRandom seed is never initialized so all instances generate the same sequence

[Chris Hegarty]

On 06/16/11 05:32 PM, Mike Duigou wrote:
Hi Chris;
The getClass() seems unnecessary. Why not :

     public Random(long seed) {
             this.seed = new AtomicLong();
             setSeed(seed);
     }

or

private final AtomicLong seed = new AtomicLong();

public Random(long seed) {
     setSeed(seed);
     }

Both of these would seem to have the same effect without needing to do the 
explicit class check.

The change ( originally from Martin ) tries to save a couple of volatile 
writes in the common case. Yes, it's not a pretty as it could be.

-Chris.


Mike

On Jun 16 2011, at 03:18 , Chris Hegarty wrote:

Hi,

ThreadLocalRandom uses its own seed, not the seed of the super class.

    ThreadLocalRandom() {
        super();
        initialized = true;
    }

This uselessly initializes the parent seed via the default constructor but 
leaves the real seed at zero.

Webrev:
  http://cr.openjdk.java.net/~chegar/7051516/jdk8_webrev.00/webrev/

Note:
  This is a port of the fix from Doug's CVS to OpenJDK. A test has been added 
to Doug's CVS tck tests for ThreadLocalRandom, and I will file a CR against the 
JCK to have it pulled in to JCK8.

-Chris.