Hi Thorsten! Does MaxGCPauseMillis apply to System.gc() too? I thought this was for the incremental collections.
> Did you parse gc logs or by hand/feel? What, do you think I'm a beginner??? :D Joke aside, yes it was just "by feel". I know I should measure it properly. Is timing the call to System.gc() an acceptable way to measure this? As far as I know, it only returns after GC has actually completed. > If you are certain that you don't need more than 800mb of live objects, limit the maxheap to something like 1.5 gb. Hmm, I am rather not that certain about that... I'd like to keep the max heap around 6 GB. On Mon, 28 Jun 2021 at 09:35, Thorsten <t...@freigmbh.de> wrote: > Hello, > > You should not get seconds long stop the world event. How did you measure > the pauses? Did you parse gc logs or by hand/feel? > > The desired max pause for g1 can be tuned using > > -XX:MaxGCPauseMillis=200 > > , so 200 ms max pause should be the default. > > It would be helpfull if you take gc logs and provide them. What java > version are you using? In old java versions g1 is fairly bad, quality > improves in newer versions. > > You can tune and change the garbage collector using -XX Options, see for > example here > https://ionutbalosin.com/2020/01/hotspot-jvm-performance-tuning-guidelines/ > > Maybe you find one of the experimental garbage collectors helpfull for > your application. > > Another simple "Hack" to tune your gc speed: If you are certain that you > don't need more than 800mb of live objects, limit the maxheap to something > like 1.5 gb. That way your app is simply unable to collect gigabytes of > garbage and your max pauses will go down. > > Best regards, > > Thorsten > > > > _______________________________________________ > hotspot-gc-use mailing list > hotspot-gc-use@openjdk.java.net > https://mail.openjdk.java.net/mailman/listinfo/hotspot-gc-use > -- Stefan Reich BotCompany.de // Java-based operating systems
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