Request for review (XXS): 7067973: test/java/lang/management/MemoryMXBean/CollectionUsageThreshold.java hanging intermittently

[Bengt Rutisson]

Hi all,

Can I have a couple of reviews for this really small change?
http://cr.openjdk.java.net/~brutisso/7067973/webrev.00/

Background:
The CollectionUsageThreshold test fails with G1. The test lowers the 
notification threshold for the G1 old gen memory pool and expects to get 
a notification after a full GC.

The problem in G1 is that the decision to send the notification is done 
in TraceMemoryManagerStats::~TraceMemoryManagerStats(). This eventually 
does pool->get_memory_usage() to get the memory usage after a 
collection. The problem is that we update this information in 
G1MonitoringSupport::update_sizes() which is called in 
G1CollectedHeap::do_collection() _after_ the TraceMemoryManagerStats 
scope had been exited.

Extending the scope to cover the call to 
G1MonitoringSupport::update_sizes() solves the issue.

Testing:
Before this change the CollectionUsageThreshold failed every time I ran 
it. After this change it passes every time I ran it.

Thanks,
Bengt