RFR: 8204170: MXBeanException.java assumes the existence of a pool that doesn't support usage threshold

[Erik Österlund]

Hi Stefan,

Looks good.

Thanks,
/Erik

On 2018-05-31 15:38, Stefan Karlsson wrote:
> Hi all,
>
> Please review this patch to deal with the case when all available 
> MemoryPoolMXBeans support usage thresholds.
>
> http://cr.openjdk.java.net/~stefank/8204170/webrev.01/
> https://bugs.openjdk.java.net/browse/JDK-8204170
>
> The tests searches for a MemoryPoolMXBean that returns false for 
> isUsageThresholdSupported(), and then uses one of those pools to 
> trigger UnsupportedOperationExceptions when setUsageThreshold is used.
>
> ZGC doesn't provide a pool that doesn't support usage threshold, and 
> the test therefore throws an NPE.
>
> The suggested fix is to add:
>         if (pool == null) {
>           return; // All pools support usage threshold
>         }
>
> An alternative fix would be to filter out the test if ZGC is used.
>
> Thanks,
> StefanK