5 ms·

Great to see progress in this space. I remember trying out G1 for the first time years ago and almost immediately noping out of it as the performance was terrib

Great to see progress in this space. I remember trying out G1 for the first time years ago and almost immediately noping out of it as the performance was terrible. Working in low-latency space the angle for me is much more about GC latency (in microsecond-level scales). I've never seen anyone doing a thorough evaluation of GC times across different implementations. Does anyone here have any interesting sources to share?

noelwelsh 7y ago
I haven't spent much time in the world of JVM tuning, but if latency is your main concern the relatively new ZGC should be your jam: https://wiki.openjdk.java.net/display/zgc/Main https://wiki.openjdk.java.net/display/zgc/Main
- pron 7y ago
  Yep. ZGC will soon offer worst-case pauses of <1ms (it's around 2-3 now).
  - The_rationalist 7y ago
    For how much % less of throughput tough?
    - pron 7y ago
      You can take a look at the slides and talks here: https://wiki.openjdk.java.net/display/zgc/ https://wiki.openjdk.java.net/display/zgc/
      - The_rationalist 7y ago
        Thanks! Nice to know they added support for class data sharing in jvm 15!
  - maxpert 7y ago
    Is ZGC production ready? Specially with JVM11?
    - noelwelsh 7y ago
      I haven't used it myself but I have heard others do so with success. It looks like JDK14 has some significant improvements to ZGC so I would try to run on that if possible. I might do some performance tests of my own soon.
    - pron 7y ago
      It will be declared non-experimental in 15, but people are running it in production on 14. GCs, and performance in general, tend to improve quite significantly between releases.
      - MaxBarraclough 7y ago
        Great news. How about the rival Shenandoah GC?
        pron 7y ago
        They're both non-experimental in 15: https://openjdk.java.net/projects/jdk/15/ https://openjdk.java.net/projects/jdk/15/
  - bitcharmer 7y ago
    This is interesting; I would really appreciate source on this. Also, what are the parameters for this assessment (cpu count, cpu frequency, memory frequency, heap size, object demography etc)?
    - pron 7y ago
      There's material here (talks, slides etc.): https://wiki.openjdk.java.net/display/zgc/ https://wiki.openjdk.java.net/display/zgc/ I think the plan is to reach the 1ms worst-case goal in 15 or 16.

noelwelsh 7y ago

I haven't spent much time in the world of JVM tuning, but if latency is your main concern the relatively new ZGC should be your jam: https://wiki.openjdk.java.net/display/zgc/Main https://wiki.openjdk.java.net/display/zgc/Main

pron 7y ago
Yep. ZGC will soon offer worst-case pauses of <1ms (it's around 2-3 now).
- The_rationalist 7y ago
  For how much % less of throughput tough?
  - pron 7y ago
    You can take a look at the slides and talks here: https://wiki.openjdk.java.net/display/zgc/ https://wiki.openjdk.java.net/display/zgc/
    - The_rationalist 7y ago
      Thanks! Nice to know they added support for class data sharing in jvm 15!
- maxpert 7y ago
  Is ZGC production ready? Specially with JVM11?
  - noelwelsh 7y ago
    I haven't used it myself but I have heard others do so with success. It looks like JDK14 has some significant improvements to ZGC so I would try to run on that if possible. I might do some performance tests of my own soon.
  - pron 7y ago
    It will be declared non-experimental in 15, but people are running it in production on 14. GCs, and performance in general, tend to improve quite significantly between releases.
    - MaxBarraclough 7y ago
      Great news. How about the rival Shenandoah GC?
      - pron 7y ago
        They're both non-experimental in 15: https://openjdk.java.net/projects/jdk/15/ https://openjdk.java.net/projects/jdk/15/
- bitcharmer 7y ago
  This is interesting; I would really appreciate source on this. Also, what are the parameters for this assessment (cpu count, cpu frequency, memory frequency, heap size, object demography etc)?
  - pron 7y ago
    There's material here (talks, slides etc.): https://wiki.openjdk.java.net/display/zgc/ https://wiki.openjdk.java.net/display/zgc/ I think the plan is to reach the 1ms worst-case goal in 15 or 16.