[jboss-user] [Performance Tuning] - VM and GC tuning for JBoss

viniciuscarvalho do-not-reply at jboss.com
Tue Nov 21 12:48:43 EST 2006

Hello there tuning masters! I've read a very interesting post here and after spent a good time reading sun's GC Tuning, Ergonomics, OnJava and JBoss wiki regarding this topic.
We have an application that (today starts only with -Xms1024m -Xmx2520m) and after collecting GC information I got a bit worried.
We're loosing throughput cause there's no youngGen default size, I believe that increasing it would help a lot (please advice on this :) )
But also, what is worrying me the most is that the major collection is taking too long to run (after application is running for a while (6-8 hours)).
Another issue I found is that the memory size is increasing in certain situations for the tenured generation

Sample of Oldgen taking too long:

  | 11866.646: [Full GC [PSYoungGen: 11216K->0K(753920K)] [PSOldGen: 1648071K->1535604K(1747648K)] 1659287K->1535604K(2501568K) [PSPermGen: 95147K->95147K(96384K)], 4.4093300 secs]
  | 11871.120: [GC [PSYoungGen: 3777K->1056K(753216K)] 1539382K->1536660K(2500864K), 0.0318290 secs]
  | 11871.152: [Full GC [PSYoungGen: 1056K->0K(753216K)] [PSOldGen: 1535604K->1431360K(1747648K)] 1536660K->1431360K(2500864K) [PSPermGen: 95177K->94436K(95360K)], 4.7277330 secs]

Sample of OldGen increasing instead of shrinking

  | 9203.157: [Full GC [PSYoungGen: 61141K->0K(635008K)] [PSOldGen: 1397552K->1441375K(1747648K)] 1458693K->1441375K(2382656K) [PSPermGen: 92656K->92656K(92800K)], 3.5918050 secs]
  | 9266.891: [Full GC [PSYoungGen: 72411K->0K(707520K)] [PSOldGen: 1441375K->1443979K(1747648K)] 1513786K->1443979K(2455168K) [PSPermGen: 92692K->92692K(92800K)], 3.9132890 secs]

Any advice on this would be really appreciated :)

Best regards

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