The improvement in throughput is tantalising. I'd love to see a comparison to the G1GC throughput. I wonder if it's getting close enough that ZGC might some day become a candidate to replace G1 as the default collector?
Our app was collecting pretty heavily, and an average collection time of about 50ms. With Z, and Linux huge pages it was collecting sub millisecond. This was at the cost of a bit more cpu, as z uses more threads for collection.
Using gatling for performance testing, we saw a small increase in requests per second. But the benefit was a smoother response time, with less spikes to high p9X measures.
Using flight recorder with this is a great way to get details of how the gc is performing.
Addendum: As noted below zgc uses more memory, I only found it viable on 16GB heaps or above. With it really improving performance around 32GB.
But, I'm no JVM experts and might have understood it incorrectly. Happy to be corrected!
That said, for a lot of use cases, this is still a reasonable trade-off to make, but it probably won't be promoted to "standard" until it's better in all use cases.
I suppose it's possible to fix this with a change to the design in some way. But if you have a heap smaller than 32GB, the existing G1 would probably work well too. ZGC shines much more on very large heap sizes since that's where long tail GC latency often hits hardest.