[Deploying Sakai] GC tuning

Fri Jun 19 06:22:50 PDT 2009

So with our new environment we decided to not do a whole lot of GC tuning on
the JVM - and since it's a low usage point we're able to do some tweakage
over the summer to iron things out. Also, since we have moved to 64bit, I
felt that experienced gained in keeping our 32bit environment alive might
not be 100% relevant. Here's where we are today:

-Xmx5000m
-Xms5000m
-XX:MaxPermSize=275m
-XX:+UseConcMarkSweepGC
-XX:+UseParNewGC

I'm seeing the occaisonal Full GC show up in the logs - but the odd thing is
that it doesn't seem to be doing much (e.g. it's not freeing a ton of memory
and is taking .02 sec). So maybe this is good? I've pasted some of the log
below...

The only other note is that we've had one JVM crash about 48 hours after
go-live - looks like the same hotspot dump that other schools have seen on
1.5.0 64bit jdks. I added a -XX:ParallelGCThreads=1 as per prior discussion
- but it hasn't happened since (uptime is now ~10 days on both app servers).
Also looking at going from 1.5.0_18 to _19 - which has some GC fixes.
Perhaps by the end of summer we are on Sakai 2.6.x with a 1.6 JDK and the G1
collector ;)

673944.069: [GC 673944.069: [ParNew: 21120K->0K(21184K), 0.0280389 secs]
4551505K->4531399K(5119936K), 0.0281907 secs]
673944.202: [GC 673944.202: [ParNew: 21120K->0K(21184K), 0.0264052 secs]
4552519K->4532378K(5119936K), 0.0265548 secs]
673947.266: [GC 673947.266: [ParNew: 21120K->0K(21184K), 0.0274979 secs]
4553498K->4533606K(5119936K), 0.0276546 secs]
673947.419: [GC 673947.419: [ParNew: 21120K->0K(21184K), 0.0269971 secs]
4554726K->4534468K(5119936K), 0.0271389 secs]
673947.555: [GC 673947.555: [ParNew: 21120K->0K(21184K), 0.0272963 secs]
4555588K->4535005K(5119936K), 0.0274375 secs]
673948.363: [GC 673948.363: [ParNew: 21120K->0K(21184K), 0.0274246 secs]
4556125K->4535704K(5119936K), 0.0275905 secs]
673948.482: [GC 673948.482: [ParNew: 21120K->0K(21184K), 0.0269240 secs]
4556824K->4537534K(5119936K), 0.0270756 secs]
673951.245: [GC 673951.245: [ParNew: 21120K->0K(21184K), 0.0273682 secs]
4558654K->4538182K(5119936K), 0.0275287 secs]
673955.243: [GC 673955.244: [ParNew: 21120K->0K(21184K), 0.0280212 secs]
4559302K->4540379K(5119936K), 0.0281834 secs]
673957.031: [GC 673957.031: [ParNew: 21120K->0K(21184K), 0.0283241 secs]
4561499K->4541342K(5119936K), 0.0284796 secs]
673957.160: [GC 673957.160: [ParNew: 21120K->0K(21184K), 0.0274730 secs]
4562462K->4542682K(5119936K), 0.0276166 secs]
673958.608: [GC 673958.608: [ParNew: 21120K->0K(21184K), 0.0278859 secs]
4563802K->4543569K(5119936K), 0.0280399 secs]
673965.054: [GC 673965.055: [ParNew: 21120K->0K(21184K), 0.0295628 secs]
4564689K->4546482K(5119936K), 0.0297250 secs]
673969.255: [GC 673969.255: [ParNew: 21120K->0K(21184K), 0.0256843 secs]
4567602K->4548278K(5119936K), 0.0258376 secs]
673969.425: [GC 673969.426: [ParNew: 21120K->0K(21184K), 0.0284620 secs]
4569398K->4549761K(5119936K), 0.0286078 secs]
673969.561: [GC 673969.561: [ParNew: 21120K->0K(21184K), 0.0259897 secs]
4570881K->4550282K(5119936K), 0.0261413 secs]
673988.057: [GC 673988.057: [ParNew: 21120K->0K(21184K), 0.0277657 secs]
4571402K->4551569K(5119936K), 0.0279256 secs]
673996.040: [GC 673996.040: [ParNew: 21114K->0K(21184K), 0.0284033 secs]
4572684K->4552250K(5119936K), 0.0285555 secs]
673996.171: [GC 673996.171: [ParNew: 21120K->0K(21184K), 0.0270439 secs]
4573370K->4552649K(5119936K), 0.0271859 secs]
674023.145: [GC 674023.146: [ParNew: 21120K->0K(21184K), 0.0315351 secs]
4573769K->4553921K(5119936K), 0.0316812 secs]
674026.443: [GC 674026.443: [ParNew: 21109K->0K(21184K), 0.0266697 secs]
4575030K->4554492K(5119936K), 0.0268268 secs]
674026.583: [GC 674026.583: [ParNew: 21120K->0K(21184K), 0.0266934 secs]
4575612K->4555158K(5119936K), 0.0268405 secs]
674036.389: [GC 674036.389: [ParNew: 21120K->0K(21184K), 0.0273871 secs]
4576278K->4556339K(5119936K), 0.0275417 secs]
674058.839: [GC 674058.839: [ParNew: 21112K->0K(21184K), 0.0282330 secs]
4577452K->4557808K(5119936K), 0.0283907 secs]
674059.416: [GC 674059.416: [ParNew: 21120K->0K(21184K), 0.0275809 secs]
4578928K->4558977K(5119936K), 0.0277284 secs]
674059.660: [GC 674059.660: [ParNew: 21120K->0K(21184K), 0.0274537 secs]
4580097K->4559935K(5119936K), 0.0275886 secs]
674059.823: [GC 674059.823: [ParNew: 21120K->0K(21184K), 0.0273031 secs]
4581055K->4560971K(5119936K), 0.0274487 secs]
674060.016: [GC 674060.016: [ParNew: 21120K->0K(21184K), 0.0266193 secs]
4582091K->4561360K(5119936K), 0.0267623 secs]
674060.218: [GC 674060.219: [ParNew: 21120K->0K(21184K), 0.0272565 secs]
4582480K->4561986K(5119936K), 0.0273908 secs]
674067.516: [GC 674067.516: [ParNew: 21120K->0K(21184K), 0.0274353 secs]
4583106K->4562957K(5119936K), 0.0275944 secs]
674080.329: [GC 674080.329: [ParNew: 21120K->0K(21184K), 0.0274450 secs]
4584077K->4564727K(5119936K), 0.0276034 secs]
674080.642: [GC 674080.642: [ParNew: 21120K->0K(21184K), 0.0270861 secs]
4585847K->4565015K(5119936K), 0.0272308 secs]
674109.302: [GC 674109.302: [ParNew: 21116K->0K(21184K), 0.0285647 secs]
4586131K->4566788K(5119936K), 0.0287224 secs]
674130.314: [GC 674130.314: [ParNew: 21120K->0K(21184K), 0.0277553 secs]
4587908K->4567825K(5119936K), 0.0279218 secs]
674132.453: [GC 674132.453: [ParNew: 21120K->0K(21184K), 0.0271981 secs]
4588945K->4568896K(5119936K), 0.0273491 secs]
674160.904: [GC 674160.904: [ParNew: 21120K->0K(21184K), 0.0270696 secs]
4590016K->4569684K(5119936K), 0.0272273 secs]
674163.640: [GC 674163.641: [ParNew: 21120K->0K(21184K), 0.0274062 secs]
4590804K->4570587K(5119936K), 0.0275592 secs]
674168.555: [Full GC 674168.556: [ParNew: 21123K->0K(21184K), 0.0276196
secs] 4591710K->4571870K(5119936K), 0.0277715 secs]
674171.169: [GC 674171.169: [ParNew: 21106K->0K(21184K), 0.0272626 secs]
4592977K->4573073K(5119936K), 0.0274149 secs]
674184.452: [GC 674184.453: [ParNew: 21120K->0K(21184K), 0.0275070 secs]
4594193K->4574073K(5119936K), 0.0276669 secs]
674188.327: [GC 674188.327: [ParNew: 21110K->0K(21184K), 0.0270553 secs]
4595184K->4575200K(5119936K), 0.0272123 secs]
674188.615: [GC 674188.615: [ParNew: 21120K->0K(21184K), 0.0273522 secs]
4596320K->4575994K(5119936K), 0.0275027 secs]
674197.072: [GC 674197.072: [ParNew: 21120K->0K(21184K), 0.0281257 secs]
4597114K->4576925K(5119936K), 0.0282824 secs]
674292.810: [GC 674292.810: [ParNew: 21120K->0K(21184K), 0.0285221 secs]
4598045K->4577880K(5119936K), 0.0286827 secs]
674312.945: [GC 674312.945: [ParNew: 21108K->0K(21184K), 0.0284677 secs]
4598988K->4579756K(5119936K), 0.0286230 secs]
674313.321: [GC 674313.321: [ParNew: 21120K->0K(21184K), 0.0275321 secs]
4600876K->4580319K(5119936K), 0.0276803 secs]
674313.489: [GC 674313.489: [ParNew: 21120K->0K(21184K), 0.0264277 secs]
4601439K->4580803K(5119936K), 0.0265706 secs]
674324.845: [GC 674324.846: [ParNew: 21120K->0K(21184K), 0.0277776 secs]
4601923K->4581911K(5119936K), 0.0279295 secs]
674348.918: [GC 674348.918: [ParNew: 21105K->0K(21184K), 0.0283547 secs]
4603017K->4585045K(5119936K), 0.0285190 secs]
674358.270: [GC 674358.270: [ParNew: 21120K->0K(21184K), 0.0278701 secs]
4606165K->4585897K(5119936K), 0.0280249 secs]
674363.214: [GC 674363.214: [ParNew: 21120K->0K(21184K), 0.0268482 secs]
4607017K->4586964K(5119936K), 0.0270045 secs]
674364.024: [GC 674364.024: [ParNew: 21120K->0K(21184K), 0.0265462 secs]
4608084K->4588049K(5119936K), 0.0266981 secs]
674369.455: [GC 674369.456: [ParNew: 21120K->0K(21184K), 0.0279544 secs]
4609169K->4589127K(5119936K), 0.0281339 secs]
674369.561: [GC 674369.561: [ParNew: 21120K->0K(21184K), 0.0271720 secs]
4610247K->4590060K(5119936K), 0.0273208 secs]
674388.177: [GC 674388.177: [ParNew: 21120K->0K(21184K), 0.0279420 secs]
4611180K->4591118K(5119936K), 0.0281027 secs]
674388.738: [GC 674388.738: [ParNew: 21120K->0K(21184K), 0.0281937 secs]
4612238K->4592098K(5119936K), 0.0283466 secs]
674388.876: [GC 674388.876: [ParNew: 21120K->0K(21184K), 0.0259139 secs]
4613218K->4592687K(5119936K), 0.0260632 secs]
674389.007: [GC 674389.007: [ParNew: 21120K->0K(21184K), 0.0263250 secs]
4613807K->4593246K(5119936K), 0.0264708 secs]
674389.201: [GC 674389.201: [ParNew: 21120K->0K(21184K), 0.0272454 secs]
4614366K->4593743K(5119936K), 0.0273900 secs]
674389.426: [GC 674389.426: [ParNew: 21120K->0K(21184K), 0.0275242 secs]
4614863K->4594257K(5119936K), 0.0276798 secs]
674407.609: [GC 674407.609: [ParNew: 21120K->0K(21184K), 0.0286980 secs]
4615377K->4595266K(5119936K), 0.0288549 secs]
674412.488: [GC 674412.488: [ParNew: 21120K->0K(21184K), 0.0277204 secs]
4616386K->4595809K(5119936K), 0.0278722 secs]
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