https://issues.apache.org/jira/browse/SOLR-14263
> On Feb 15, 2020, at 10:17 AM, Mike Drob <md...@apache.org> wrote: > > Erick, > > Can you drop a link to that Jira here after you create it? > > Many thanks, > Mike > > On Fri, Feb 14, 2020 at 6:05 PM Erick Erickson <erickerick...@gmail.com> > wrote: > >> I just read that page over and it looks way out of date. I’ll raise >> a JIRA. >> >>> On Feb 14, 2020, at 2:55 PM, Walter Underwood <wun...@wunderwood.org> >> wrote: >>> >>> Yeah, that is pretty outdated. At Netflix, I was running an 8 GB heap >> with Solr 1.3. :-) >>> >>> Every GC I know about has a stop-the-world collector as a last ditch >> measure. >>> >>> G1GC limits the time that the world will stop. It gives up after >> MaxGCPauseMillis >>> milliseconds and leaves the rest of the garbage uncollected. If it has 5 >> seconds >>> worth of work to do that, it might take 10 seconds, but in 200 ms >> chunks. It does >>> a lot of other stuff outside of the pauses to make the major collections >> more effective. >>> >>> We wrote Ultraseek in Python+C because Python used reference counting and >>> did not do garbage collection. That is the only way to have no pauses >> with >>> automatic memory management. >>> >>> wunder >>> Walter Underwood >>> wun...@wunderwood.org >>> http://observer.wunderwood.org/ (my blog) >>> >>>> On Feb 14, 2020, at 11:35 AM, Tom Burton-West <tburt...@umich.edu> >> wrote: >>>> >>>> Hello, >>>> >>>> In the section on JVM tuning in the Solr 8.3 documentation ( >>>> https://lucene.apache.org/solr/guide/8_3/jvm-settings.html#jvm-settings >> ) >>>> there is a paragraph which cautions about setting heap sizes over 2 GB: >>>> >>>> "The larger the heap the longer it takes to do garbage collection. This >> can >>>> mean minor, random pauses or, in extreme cases, "freeze the world" >> pauses >>>> of a minute or more. As a practical matter, this can become a serious >>>> problem for heap sizes that exceed about **two gigabytes**, even if far >>>> more physical memory is available. On robust hardware, you may get >> better >>>> results running multiple JVMs, rather than just one with a large memory >>>> heap. " (** added by me) >>>> >>>> I suspect this paragraph is severely outdated, but am not a Java expert. >>>> It seems to be contradicted by the statement in " >>>> >> https://lucene.apache.org/solr/guide/8_3/taking-solr-to-production.html#memory-and-gc-settings >> " >>>> "...values between 10 and 20 gigabytes are not uncommon for production >>>> servers" >>>> >>>> Are "freeze the world" pauses still an issue with modern JVM's? >>>> Is it still advisable to avoid heap sizes over 2GB? >>>> >>>> Tom >>>> https://www.hathitrust.org/blogslarge-scale-search >>> >> >>
