-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Jesse,
On 2/2/2010 3:23 AM, Jesse Klaasse wrote: > Christopher Schultz-2 wrote: >> >> Can you give us a timestamp for when the trouble started? Reading GC >> output is pretty tedious. >> > > I believe the trouble started around 15 - 20 minutes before the end of the > gc log, so that would be from ~61h36m. That's 221760 minutes, and you only have two GC log lines near or after that time: 222745.754: [GC 222745.754: [ParNew: 2566632K->34378K(2831168K), 0.1180327 secs] 3272635K->747297K(7025472K), 0.1187242 secs] [Times: user=0.44 sys=0.02, real=0.13 secs] 223001.755: [GC 223001.756: [ParNew: 2550986K->55967K(2831168K), 0.1662147 secs] 3263905K->775682K(7025472K), 0.1667915 secs] It's interesting that there's no timing data for that last statement. It /is/ possible this is where the JVM went down. (Did it go down?) Both of these GC runs seem to be collecting a /lot/ of garbage: 3272635K->747297K That's a reduction of roughly 75%... though I guess in .13 seconds, it's not taking so long, so it should be fine. I guess your webapp generates a lot of temporary data, fast. At least it gets cleaned-up quickly. >> Also, what happens if you remove all your *GC* options (other than >> logging) from your JAVA_OPTS? > > I am quite hesitant to try this. This is a production environment, and all > in all Tomcat is performing pretty good now, in comparison to what the > situation was before. Do you have a place where you can really play around with this? > By "all" GC options, do you also mean the UseConcMarkSweepGC? Wouldn't the > GC become serial then (with pauses which stop the whole webapp for a while)? I don't believe the GC will do "serial" collections unless explicitly told to do that. The days of "stop the world" garbage collection are long gone. > And also the +DisableExplicitGC? That only causes the JVM to ignore calls to System.gc(), which aren't guaranteed to do anything, anyway. Unless you are deploying unknown webapps, this probably isn't doing anything at all. >> Is this reproducible? > > Well, as I said, Tomcat is working much more stable now than it did before. > However, once in a few days it still becomes unresponsive, while CPU usage > stays incredibly low. I have tried load tests using jMeter on our > development environment, but it's working fine then. Must have something to > do with the "real" (more diverse, less predictable/repetitive) traffic on > the production environment, I guess.. I'd be interested in what a thread dump shows you during one of these pauses. I agree with Dan: this sounds much more like your webapp is waiting around for something like a db connection than doing anything active. If the GC were running like crazy, I suspect you'd see more CPU usage. - -chris -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEUEARECAAYFAktojf4ACgkQ9CaO5/Lv0PAcAwCWJdL0fddltpbT4xliEY3Cgiqc 3QCfYE4EvIedEbFtQnGWVbij29Oz234= =rVYe -----END PGP SIGNATURE----- --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
