Review Request for 6878481: Add performance counters in the JDK
Alan.Bateman at Sun.COM
Thu Sep 3 15:44:22 UTC 2009
Andrew John Hughes wrote:
> The use of synchronized at present seems flawed as only the set
> methods are protected and not the get. So lb.get could be called
> while in an lb.put call. I don't see the reason for using a
> LongBuffer either, as only index 0 is ever used. Why not use an
The LongBuffer is a direct buffer with a reference to memory in the
PerfData instrumentation buffer. This is the shared memory that jvmstat
clients (jstat, VisualVM , ..) will attach to in order to monitor the VM.
> What is the purpose of d3dAvailable? I don't know this piece of code
> so I'm not sure what it's counting, but it will presumably be zero
> forever on non-Windows systems.
Mandy can say more about this, but it essentially allows jstat to see if
the target VM is using the D3D pipeline or not.
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