RFR: 8025226: TestPerfCountersAndMemoryPools.java fails with -Xmixed or -Xcomp

[Erik Helin]

Based on feedback from Bengt, I was able to remove one call to
System.gc() and I also added comments that explains why the two other
calls are necessary.

Please see new webrev at:
http://cr.openjdk.java.net/~ehelin/8025226/webrev.01/

Thanks,
Erik

On 2013-09-30, Erik Helin wrote:
> Hi all,
> 
> this change fixes the test
> hotspot/test/gc/metaspace/TestPerfCountersAndMemoryPools.java which was
> broken when running with -Xcomp or -Xmixed. The problem was that the
> call to MemoryUsage.getUsed() triggered allocations of metadata. Since
> the performance counters are only updated at the end of a GC, this
> caused the performance counter and the memory pool for used metadata to
> differ in how much they reported.
> 
> The solution is to only run the test in the interpreter by using -Xint.
> 
> I also added the tag @library tag which was missing from the test. The
> test had never been run on "its own" before, the testlibrary had always
> been compiled by another test before the test was run.
> 
> Finally, the test now only loops through the MemoryPoolMXBeans once to
> find the correct memory pool.
> 
> Webrev:
> http://cr.openjdk.java.net/~ehelin/8025226/webrev.00/
> 
> Bug:
> https://bugs.openjdk.java.net/browse/JDK-8025226
> 
> Thanks,
> Erik