Shenandoah experimental flags

[Cristian Velazquez]

Hi everyone:

I'm testing out shenandoah on https://github.com/gaul/java-httpbin. I'm
using wrk to send a huge amount of traffic: wrk -d 300 -t 1 -c 32
http://127.0.0.1:8080/gzip. I'm using the default flags with 2G heap. I'm
getting pause times from 100-300ms due to the time spent on finish queues.

I tried the following (I used as reference this
https://mail.openjdk.java.net/pipermail/shenandoah-dev/2018-July/006630.html
):
- Reduce ShenandoahSATBBufferFlushInterval to 1 ms. This didn't make any
difference.
- Reduce ShenandoahSATBBufferSize to 32. This fixed the issue and now see
better pause times.

I have run it for quite a while and I haven't seen any issue with this
configuration. Although, I would like to know what is the recommendation in
this scenario? is it safe to decrease the buffer size? what is the impact
of doing so?

Thanks, regards
       Cristian Velazquez