high StringTable scanning overhead during young GCs

[Stefan Johansson]

Hi Tony,

> 16 mars 2020 kl. 22:02 skrev Tony Printezis <tprintezis at twitter.com>:
> 
> ...
> 
> FWIW, we use mostly CMS in 8 and we addressed this by forcing more frequent
> CMS cycles (we have a flag that starts a CMS cycle every N secs). This
> helps to keep young GC times mostly in check for our services that suffer
> from this issue.
> 
If you want to try a similar workaround for G1. In JDK 12, G1PeriodicGCInterval was added as part of JEP 346: Promptly Return Unused Committed Memory from G1. This flag allows you to trigger GCs based on that interval, and by default the GC triggered start a concurrent cycle. This feature was mostly designed for idle applications and the periodic request will be skipped if any GC occurred in the interval, so depending on your workload disabling adaptive IHOP and setting a lower fixed IHOP might be better approach.

Thanks,
Stefan

> ...
> —————
> Tony Printezis | @TonyPrintezis | tprintezis at twitter.com