> I don’t think having the initial heap larger than the max heap is a legal configuration. > I have no idea what that would do.
Sorry my wording was poor. I meant if, instead of my initial HEAP of 512MB, it was closer to say 6 or 8GB or equal to my Max allowed of 10GB. Appreciate the info though. Thanks Watler Nick On Thu, Oct 3, 2019 at 10:57 AM Walter Underwood <wun...@wunderwood.org> wrote: > I don’t think having the initial heap larger than the max heap is a legal > configuration. > I have no idea what that would do. > > Modern GCs have a separate area for short-lived allocations. When that > fills up, > a minor GC happens. As allocations survive several minor GCs, they are > moved > to the long-lived space, which is managed by major GCs. This is called a > generational > collector. > > In Solr, nearly all allocations are for a single request, so those are > garbage after the > response is sent. Most of the action will be in the new allocation > (short-lived) space. > Cache allocations get moved to the long-lived space. > > wunder > Walter Underwood > wun...@wunderwood.org > http://observer.wunderwood.org/ (my blog) > > > On Oct 3, 2019, at 10:11 AM, ndra <publicmlu...@gmail.com> wrote: > > > >> When the heap is out of free space that > >> can be recovered with minor GC, the JVM will increase the size if > possible. > >> Once it is at max, it will do a major GC. > > > > Thanks Walter, > > > > One more quick question about the above, so if the initial HEAP was > larger > > (or equal to the max as you suggested earlier) will the GCs minor GCs be > > less frequent because the HEAP still has available space? > > > > Unfortunately the system was rebooted by a infrastructure person prior to > > looking at `/admin/system/info` endpoint to look at the stats. Is there > > another way get those statistics (there is no JVM monitoring in place > from > > our INF team so I am starting this all from scratch right now. > > > > Nick > > > > > > On Thu, Oct 3, 2019 at 9:44 AM Walter Underwood <wun...@wunderwood.org> > > wrote: > > > >>> On Oct 3, 2019, at 9:31 AM, ndra <publicmlu...@gmail.com> wrote: > >>> > >>> I was under the impression that by allocating a smaller initial HEAP I > >>> could avoid having a larger GCs but if I am understanding what you all > >> are > >>> suggesting, the smaller initial HEAP is requiring more full GCs to > >> maintian > >>> a HEAP closer to 512MB. Is that correct? > >> > >> I don’t think either of those are true. When the heap is out of free > space > >> that > >> can be recovered with minor GC, the JVM will increase the size if > possible. > >> Once it is at max, it will do a major GC. > >> > >> We use these settings in solr.in.sh: > >> > >> SOLR_HEAP=8g > >> # Use G1 GC -- wunder 2017-01-23 > >> # Settings from https://wiki.apache.org/solr/ShawnHeisey > >> GC_TUNE=" \ > >> -XX:+UseG1GC \ > >> -XX:+ParallelRefProcEnabled \ > >> -XX:G1HeapRegionSize=8m \ > >> -XX:MaxGCPauseMillis=200 \ > >> -XX:+UseLargePages \ > >> -XX:+AggressiveOpts \ > >> " > >> wunder > >> Walter Underwood > >> wun...@wunderwood.org > >> http://observer.wunderwood.org/ (my blog) > >> > >> > >
