In the abstract, it sounds like you are seeing the difference between tuning for latency vs tuning for throughput
My hunch would be you are seeing more (albeit individually quicker) GC events with your new settings during the rebuild I imagine that in most cases a solr rebuild is relatively rare compared to the amount of times where a lower latency request is desired. If the rebuild times are problematic for you, use tunings specific to that workload during the times you need it and then switch back to your low latency settings after. If you are doing that you can probably run with a bigger heap temporarily during the rebuild as you aren't likely to be fielding queries and don't benefit from having a larger OS cache available Sent from my iPhone > On Jan 8, 2015, at 20:54, Shawn Heisey <apa...@elyograg.org> wrote: > > Is it possible that tuning garbage collection to achieve much better > pause characteristics might actually *decrease* index performance? > > Rebuilds that I did while still using a tuned CMS config would take > between 5.5 and 6 hours, sometimes going slightly over 6 hours. > > A rebuild that I did recently with G1 took 6.82 hours. A rebuild that I > did yesterday with further tuned G1 settings (which seemed to result in > much smaller pauses than the previous G1 settings) took 8.97 hours, and > that was on slightly faster hardware than the rebuild that took 6.82 hours. > > These rebuilds are done with DIH from MySQL. > > It seems completely counter-intuitive that settings which show better GC > pause characteristics would result in indexing performance going down > ... so can anyone shed light on this, tell me whether I'm out of my mind? > > Thanks, > Shawn >
