I should mention here that if you are tuning the GC anywhere except at the end of your development cycle you're probably doing it wrong. 99% of the time you'll get better performance by reviewing your algorithms, running a CPU profiler, generating less garbage (via transients or something like that), or adding some missing type hints. You can spend a ton of time in GC optimization, but I've never seen yield huge results. Maybe 10% here or there, but I normally get orders of magnitude performance increases spending just a few hours with a CPU profiler.
So it's one of those things where "if you don't know if you should change a GC setting form the default, you probably don't". On Sat, Apr 30, 2016 at 12:44 PM, Nando Breiter <na...@aria-media.com> wrote: > I've found Censum by jClarity to be an excellent tool to tune JVM GC > parameters to your specific application running on a particular server. You > add a few GC parameters to enable logging that the tool needs, run your app > under load for enough time to get sufficient data, and then feed the log > directly into Censum, which analyzes it and then suggests improvements that > can be made to your GC parameters. There is also a list where you can ask > questions about the analysis and its suggestions and get in depth replies > from people who have extensive experience tuning JVMs. > > https://www.jclarity.com/censum/ > > > > Aria Media Sagl > +41 (0)76 303 4477 cell > skype: ariamedia > > On Sat, Apr 30, 2016 at 11:50 AM, Niels van Klaveren < > niels.vanklave...@gmail.com> wrote: > >> GC parameters used by a lot of projects are handed down like traditions >> for years, even spreading to others. They're almost never re-evaluated, >> which means they might actually lose out on new performance improvements, >> or worse, might even cause performance regressions. >> >> Most parameters in the Overtone lib for instance have been the default >> for quite some time (ParNew GC, TLAB). Where restricting New Gen might be a >> good idea to reduce new gen GC latency, it can cause unwanted promotions, >> longer tenured GC's and in the end heap fragmentation resulting in a full >> defrag gc that can take 10s of seconds. >> >> Defaults are there for a reason, to take care of most situations. Any >> settings other than the three default Garbage Collectors (Default for >> shortest time to finish, CMS for shortest pause , G1 for short pauses but >> long running times) and at most a pause hint for their heuristics means >> you're entering case-specific territory and should be treating it so. >> >> This means realistic benchmarking, profiling and comparisons between >> different settings. I'd treat any JVM product or library with more than 2 >> GC parameters with care, because if they need so much tweaking as their >> default, you can be sure to need both a good understanding of their inner >> workings and JVM memory managent as well to keep them performing in your >> specific case. >> >> -- >> You received this message because you are subscribed to the Google >> Groups "Clojure" group. >> To post to this group, send email to clojure@googlegroups.com >> Note that posts from new members are moderated - please be patient with >> your first post. >> To unsubscribe from this group, send email to >> clojure+unsubscr...@googlegroups.com >> For more options, visit this group at >> http://groups.google.com/group/clojure?hl=en >> --- >> You received this message because you are subscribed to the Google Groups >> "Clojure" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to clojure+unsubscr...@googlegroups.com. >> For more options, visit https://groups.google.com/d/optout. >> > > -- > You received this message because you are subscribed to the Google > Groups "Clojure" group. > To post to this group, send email to clojure@googlegroups.com > Note that posts from new members are moderated - please be patient with > your first post. > To unsubscribe from this group, send email to > clojure+unsubscr...@googlegroups.com > For more options, visit this group at > http://groups.google.com/group/clojure?hl=en > --- > You received this message because you are subscribed to the Google Groups > "Clojure" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to clojure+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. > -- “One of the main causes of the fall of the Roman Empire was that–lacking zero–they had no way to indicate successful termination of their C programs.” (Robert Firth) -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups "Clojure" group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
