System.gc() causes for jcl (BufferPoolMXBean)

Alan Bateman Alan.Bateman at
Sat Jun 20 16:12:34 UTC 2015

On 19/06/2015 20:42, Bernd Eckenfels wrote:
> :
>  From my point of view tracking native allocations in "internal" pool
> (via Unsafe.allocate) is hard. (see my other discussion on
> instrumenting Unsafe). Making some of the users (especially
> DirectByteBuffers) more transparent would be a good thing.
> This includes peak usage but also allocation rate and especially the
> backoff/system-gc case. So from my side, I think it is a good thing to
> add some metrics here and I am willing to work on a patch.
Tracking peak usage would be consistent with some of the other platform 
MXBeans so I think this make sense.

Back-off + gc is implementation specific and I don't think appropriate 
to add to the BufferPoolMXBean. This type of tracking might be better 
served with jvmstat counters. JFR isn't in OpenJDK but others here might 
be able to say whether it could make use of the counters and updated 


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