Unexpected issues with Final Mark pauses and pacer performance in JDK11

[Aleksey Shipilev]

On 7/17/20 6:56 AM, Connaughton, Niall wrote:
> What angles can I look at to dig into the cause of increasing Final Mark pauses? I don’t see a
> lot of details on the Final Mark in the gc logs, 

-Xlog:gc+stats would give you verbose per-cycle pause details on a recent enough sh/jdk11 (including
the one released with 11.0.8).

> The second issue I ran into was that the pacer seemed to be adding a lot of latency. I couldn’t
> find any traces in the logs of the pacer’s activity. 

There is no bindings to per-cycle stats, alas.

I had a patch before, but never actually pushed it to inclusion:
  https://bugs.openjdk.java.net/browse/JDK-8249649

> Disabling the pacer removed the latency impact
> and we started seeing some really positive signs on the latency. I was expecting that we’d just
> see more degenerated GC and the latency would be similar, but this wasn’t the case.
Again, recent improvements in pacer might resolve this. Recent sh/jdk11 (including the one released
with 11.0.8) has most of them.

Please try with 11.0.8+?

-- 
Thanks,
-Aleksey