Use -XX:MaxTenuringThreshold=2 and you might see better behavior that +AlwaysTenure (which is almost always a very bad choice). That will at least reduce some of the nepotism issues from +AlwaysTenure that Thomas mentions. MTT > 2 is unlikely to help at your current frequency of minor collections since the mortality after age 1 is fairly low (from your tenuring distribution). Worth a quick test.
-- ramki On Mon, Oct 26, 2015 at 12:33 PM, Jun Zhuang <[email protected]> wrote: > Hi, > > > > When running performance testing for a java web service running on JBOSS, > I observed a clear saw-tooth pattern in CPU utilization that closely > follows the GC cycles. see below: > > > > > > Java startup parameters used: > > > > -XX:+TieredCompilation -XX:+PrintTenuringDistribution -Xms2048m -Xmx4096m > -XX:MaxPermSize=256m -XX:NewSize=128m -XX:MaxNewSize=128m > -XX:SurvivorRatio=126 -XX:-UseAdaptiveSizePolicy -XX:+DisableExplicitGC > -XX:+AlwaysTenure > > > > With this set of parameters, the young GC pause time ranged from 0.02 to > 0.25 secs. When I used 256m for the young gen, the young GC pause time > ranged from 0.02 to 0.5 secs. My understanding is that the young GC pause > time normally stays fairly stable, I have spent quite some time researching > but have yet to find an answer to this behavior. I wonder if people in this > distribution list can help me out? > > > > *Other related info* > > > > * Server Specs: VM with 4 CPUs and 8 Gb mem > > * Test setup: > > · # of Vusers: 100 > > · Ramp up: 10 mins > > · Pacing: 5 – 7 secs > > * I tried with all other available GC algorithms, tenuring thresholds, > various sizes of the generations, but the AlwaysTenure parameter seems to > work the best so far. > > > > > > Any input will be highly appreciated. > > > > Sincerely yours, > > > > *Jun Zhuang* > > *Sr. Performance QA Engineer | Hobsons* > > *513-746-2288 <513-746-2288> (work)* > > *513-227-7643 <513-227-7643> (mobile)* > > > > _______________________________________________ > hotspot-gc-use mailing list > [email protected] > http://mail.openjdk.java.net/mailman/listinfo/hotspot-gc-use > >
_______________________________________________ hotspot-gc-use mailing list [email protected] http://mail.openjdk.java.net/mailman/listinfo/hotspot-gc-use
