Thanks for the reviews Markus, Erik and David! Filed https://bugs.openjdk.java.net/browse/JDK-8189368 <https://bugs.openjdk.java.net/browse/JDK-8189368> for the improvement to add information on the thread currently holding the bias when it is revoked.
Best regards, Robin > On 16 Oct 2017, at 13:23, Markus Gronlund <markus.gronl...@oracle.com> wrote: > > Hi Robin, > > Looks good. > > Thanks > Markus > > From: Robin Westberg > Sent: den 13 oktober 2017 16:56 > To: David Holmes > Cc: serviceability-dev@openjdk.java.net > Subject: Re: RFR: 8187042: Events to show which objects are associated with > biased object revocations > > Hi again, > > Here’s an updated version that adds a separate event for the self-revocation > path. It’s a new event class as it is a bit different from the > non-self-revocation path, it does not have any relevant safepoint ID for > example. > > Webrev: > http://cr.openjdk.java.net/~egahlin/8187042_2/ > <http://cr.openjdk.java.net/~egahlin/8187042_2/> > > Third, I would have expected to see more detail in the event such as which > thread (id) the object was biased to and which thread revoked the bias. Even > perhaps some notion of which instance was involved (though that's harder to > shows). > Right, I’ve been looking at capturing which thread the object was biased > towards, but I was afraid of the possible races there as the thread pointer > in the mark would have to be saved before executing the VM operation. For > that to work 100% reliably I suspect it would have to be done inside the > safepoint. > > Right the thread holding the bias may not even exist any more! This may need > to utilise the new Thread-SMR work (as a future RFE of course). :) > > Ah yeah, that may be an effective way of doing it. Another idea suggested by > Markus Grönlund was to capture the thread’s id inside the operation and > propagate it through an additional field in the VM operation class. But > anyway, I’ll file a separate RFE for investigating that improvement. > > Best regards, > Robin > > > I will create an updated webrev after looking into adding an event for the > self-revocation path. > > Thanks, > David > > > Best regards, > Robin
