RFR(S): 8007701: Hotspot JFR Allocation Events

Nils Eliasson nils.eliasson at oracle.com
Thu Mar 14 13:42:40 PDT 2013

Hi all,

I would like a review for this change that introduces two new Java 
Flight Recorder events.

"AllocationInNewTLAB" is sent for the first object in a new TLAB and 
gives a reasonably cheap and reasonably fair object sampling.
"AllocationOutsideTLAB" is sent for each object that gets allocated 
outside the TLABs. (The object doesn't fit or would cause too much 
wasted free space if the tlab was discarded.)

These events use the allocation slow path in CollectedHeap which is used 
by default in the template interpreter and the C2 compiler. It is also 
used for all TLAB refills in the C1-compiler if the flag 
-XX:-FastTLABRefill is supplied.


The event code for AllocationOutsideTLAB had to be put in 
CollectedHeap.cpp since tracing.hpp can't be included into 

Nils Eliasson

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