-XX:-CMSClassUnloadingEnabled

Tony Printezis tprintezis at twitter.com
Fri Mar 11 16:12:40 UTC 2016


Thanks for the heads up Jungwoo. I think it should be straightforward to decide whether to unload classes for a particular CMS cycle based on the rate at which the meatspace occupancy is growing. Has anyone considered / looked into this?

Tony

On March 10, 2016 at 7:07:00 PM, Jungwoo Ha (jwha at google.com) wrote:

We've been disabled CMSClassUnloading for a long time and had no issues.
We recently turned it back on by default with CMSClassUnloadingMaxInterval=5, which amortizes the increased remark cost.


On Thu, Mar 10, 2016 at 1:32 PM, Tony Printezis <tprintezis at twitter.com> wrote:
Hi all,

CMSClassUnloadingEnabled is enabled by default in JDK 8. Most of our services do not require class unloading (they load a bunch of classes up-front and that’s it) so we’re thinking of turning it off by default in our JDK as it increases our remark times by a non-trivial amount (40-90ms depending on the service). Any known issues with running with -XX:-CMSClassUnloadingEnabled? (This is a veiled way to ask: is anyone testing with that flag off?)

Thanks,

Tony

-----

Tony Printezis | JVM/GC Engineer / VM Team | Twitter

@TonyPrintezis
tprintezis at twitter.com




--
Jungwoo Ha | Java Platform Team | jwha at google.com

-----

Tony Printezis | JVM/GC Engineer / VM Team | Twitter

@TonyPrintezis
tprintezis at twitter.com

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.openjdk.java.net/pipermail/hotspot-gc-dev/attachments/20160311/a4331a4d/attachment.html>


More information about the hotspot-gc-dev mailing list