Java HotSpot Virtual Machine

Hello,

I have observed the following behavior on one of our production servers running a real time system:

a) frequently, a large number (easily about 100 MB) of young generation objects are tenured over a short period of time (generally in the 2-3 minute time frame but sometimes less)

b) to see if a JVM upgrade affects/fixes this, I recently upgraded from *1.5 Update 6* to *1.6 Update 1*, but it doesnt seem to have made much difference in the sudden jumps in old generation memory

c) with 1.5, there were 'concurrent mode failure' errors in the GC log - with 1.6, those have gone away but there are "CMS: abort preclean due to time" errors, so I am not sure how effective the CMS GC really is here

I am using the following JVM options:

-Xss128k -Xmx1280m -Xms1280m -Xmn400m -XX:MaxPermSize=128m -XX:PermSize=64m
-XX:-UseParNewGC [have also tried -XX:+UseParNewGC]
-XX:+UseConcMarkSweepGC
-XX:TargetSurvivorRatio=90
-XX:MaxTenuringThreshold=1
-XX:+DisableExplicitGC
-Dcom.sun.management.jmxremote
-Dcom.sun.management.jmxremote.port=9999 -Dcom.sun.management.jmxremote.authenticate=false -Dcom.sun.management.jmxremote.ssl=false -Dsun.rmi.dgc.server.gcInterval=600000 -Dsun.rmi.dgc.client.gcInterval=600000

Any help with this is very much appreciated.

Srini.

Extracts from GC log:

...
33104.784: [GC 33104.784: [DefNew: 331143K->6384K(368640K), 0.0554633 secs] 382613K->58620K(1392640K), 0.0557271 secs]
33140.657: [GC 33140.658: [DefNew: 334064K->33299K(368640K), 0.1612125 secs] 386300K->86091K(1392640K), 0.1614336 secs]
33181.425: [GC 33181.425: [DefNew: 360979K->329K(368640K), 0.2583737 secs] 413771K->118776K(1392640K), 0.2585926 secs]
33211.468: [GC 33211.469: [DefNew: 328009K->362K(368640K), 0.4760715 secs] 446456K->249969K(1392640K), 0.4762905 secs]
33261.450: [GC 33261.451: [DefNew: 328042K->609K(368640K), 0.0317898 secs] 577649K->250275K(1392640K), 0.0320174 secs]
33295.271: [GC 33295.271: [DefNew: 243172K->535K(368640K), 0.0266738 secs] 492838K->250312K(1392640K), 0.0268943 secs]
33305.028: [GC 33305.029: [DefNew: 328215K->242K(368640K), 0.9267009 secs] 577992K->512326K(1392640K), 0.9269350 secs]
33305.959: [GC [1 CMS-initial-mark: 512084K(1024000K)] 515415K(1392640K), 0.0033297 secs]
33305.963: [CMS-concurrent-mark-start]
33306.652: [CMS-concurrent-mark: 0.690/0.690 secs]
33306.652: [CMS-concurrent-preclean-start]
33306.659: [CMS-concurrent-preclean: 0.006/0.007 secs]
33306.659: [CMS-concurrent-abortable-preclean-start]
CMS: abort preclean due to time 33311.672: [CMS-concurrent-abortable-preclean: 0.512/5.013 secs]
33311.676: [GC[YG occupancy: 51916 K (368640 K)]33311.676: [Rescan (non-parallel) 33311.676: [grey object rescan, 0.0027005 secs]33311.679: [root rescan, 0.1012596 secs], 0.1040770 secs]33311.780: [weak refs processing, 0.0013688 secs] [1 CMS-remark: 512084K(1024000K)] 564001K(1392640K), 0.1059224 secs]
33311.784: [CMS-concurrent-sweep-start]
33311.844: [CMS-concurrent-sweep: 0.060/0.060 secs]
33311.844: [CMS-concurrent-reset-start]
33311.901: [CMS-concurrent-reset: 0.056/0.056 secs]
33353.364: [GC 33353.364: [DefNew: 327922K->647K(368640K), 0.0331175 secs] 622136K->294905K(1392640K), 0.0333633 secs]
33404.531: [GC 33404.531: [DefNew: 328327K->394K(368640K), 0.0343957 secs] 622585K->294837K(1392640K), 0.0346283 secs]
.....
122196.870: [GC 122196.870: [DefNew: 335723K->33398K(368640K), 0.1694331 secs] 647278K->345664K(1392640K), 0.1696536 secs]
123378.669: [GC 123378.669: [DefNew: 361078K->3955K(368640K), 0.2014420 secs] 673344K->381801K(1392640K), 0.2016926 secs]
125537.896: [GC 125537.896: [DefNew: 331635K->8170K(368640K), 0.0786210 secs] 709481K->386306K(1392640K), 0.0788437 secs]
127581.547: [GC 127581.547: [DefNew: 335850K->5213K(368640K), 0.0953335 secs] 713986K->383790K(1392640K), 0.0955752 secs]
127636.773: [GC 127636.774: [DefNew: 332893K->0K(368640K), 0.1591214 secs] 711470K->379327K(1392640K), 0.1593282 secs]
127672.690: [GC 127672.690: [DefNew: 327680K->0K(368640K), 0.4753881 secs] 707007K->510399K(1392640K), 0.4755892 secs]
127731.905: [GC 127731.905: [DefNew: 327680K->0K(368640K), 0.0300905 secs] 838079K->510400K(1392640K), 0.0302818 secs]
127747.916: [GC 127747.916: [DefNew: 92907K->0K(368640K), 0.0116197 secs] 603307K->510400K(1392640K), 0.0118132 secs]
127760.320: [GC 127760.320: [DefNew: 327680K->0K(368640K), 0.9315203 secs] 838080K->772544K(1392640K), 0.9317222 secs]
127761.253: [GC [1 CMS-initial-mark: 772544K(1024000K)] 776067K(1392640K), 0.0024436 secs]
127761.256: [CMS-concurrent-mark-start]
127762.072: [CMS-concurrent-mark: 0.816/0.816 secs]
127762.072: [CMS-concurrent-preclean-start]
127762.078: [CMS-concurrent-preclean: 0.006/0.007 secs]
127762.078: [CMS-concurrent-abortable-preclean-start]
CMS: abort preclean due to time 127767.180: [CMS-concurrent-abortable-preclean: 0.487/5.102 secs]
127767.184: [GC[YG occupancy: 38613 K (368640 K)]127767.184: [Rescan (non-parallel) 127767.184: [grey object rescan, 0.0029299 secs]127767.187: [root rescan, 0.0925664 secs], 0.0956100 secs]127767.280: [weak refs processing, 0.0040487 secs] [1 CMS-remark: 772544K(1024000K)] 811158K(1392640K), 0.1002486 secs]
127767.286: [CMS-concurrent-sweep-start]
127767.462: [CMS-concurrent-sweep: 0.175/0.175 secs]
127767.462: [CMS-concurrent-reset-start]
127767.516: [CMS-concurrent-reset: 0.054/0.054 secs]
127819.603: [GC 127819.603: [DefNew: 327680K->1K(368640K), 0.0323185 secs] 868214K->540536K(1392640K), 0.0325146 secs]
128817.575: [GC 128817.575: [DefNew: 327681K->4032K(368640K), 0.0714104 secs] 868216K->544567K(1392640K), 0.0716335 secs]
128864.744: [GC 128864.744: [DefNew: 331712K->0K(368640K), 0.1596496 secs] 872247K->541367K(1392640K), 0.1598559 secs]
....