RFR: 8234009: ZGC: Move resurrection unblock to before the _unload.purge() call
per.liden at oracle.com
Fri Nov 22 13:08:43 UTC 2019
On 11/21/19 2:28 PM, Stefan Karlsson wrote:
> Hi all,
> Please review this patch to move the resurrection to before the
> _unload.purge() call.
> After JDK-8230661 we are guaranteed that no mutator holds a weak oop
> containing a "dead" object when the ZResurrection::unblock() call happens.
> Therefore, it doesn't matter if the load barrier that the thread
> executes runs the code guarded by ZResurrection::is_blocked() or the
> "non-blocked" part, when ZResurrection::unblock() changes the state. As
> long as the ZResurrection::unblock() call happens after the handshake,
> we are good to go.
> Today, we perform the purging and deletion of metadata in
> _unload.purge(), and call ZResurrection:unblock() after that. There's no
> need to delay the unblocking to after the purge. We have the opportunity
> to shrink the resurrection-blocked window by moving the
> ZResurrection::unblock() call to before the call to _unload.purge(), but
> still after the handshake.
More information about the hotspot-gc-dev