RFR for JDK-7027502: Test failures in demo/jvmti/hprof testcases, need to be othervm

[David Holmes]

On 9/01/2014 8:28 PM, Paul Sandoz wrote:
>
> On Jan 9, 2014, at 10:52 AM, Tristan Yan <tristan.yan at oracle.com> wrote:
>
>> Can someone else give a second review on this.
>
> In a comment the bug you state:
>
>    "here total_turns_taken is a static variable, it could affect by other tests"
>
> I don't quite know under what test circumstances that can happen, but if so is the following also an issue:
>
>    52     private final static TurnChecker turn = new TurnChecker(-1);
>
> ?
>
> FWIW an alternative to using an AtomicInteger would be for the main loop to sum up thread_turns of each Context, since read/writes are all performed in a synchronized block.

Now that you mention it ... I had mistakenly thought the switch to an 
AtomicInteger was to ensure the ++ was actually atomic, but as you note 
these updates all take place within a synchronized block that locks the 
same "turn" instance of TurnChecker.

So now I'm confused by the change. Tristan what was the basis of making 
the change that you did ? If the issue was that concurrent hprof tests 
all used the same Context class in the same VM (how??) then as Paul says 
the TurnChecker instance would also be a problem. Otherwise the change 
makes no real difference to the semantics of the test as far as I can see.

David

> Paul.
>