-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Chuck,
On 4/21/2009 5:50 PM, Caldarale, Charles R wrote: >> From: Christopher Schultz [mailto:ch...@christopherschultz.net] >> Subject: Re: Headstart on "Resolving OOM-PermGen errors on webapp >> reload" >> >> Can you observe your heap and which ClassLoaders are still hanging >> around? You might want to check to see how many >> org/apache/catalina/loader/WebappClassLoader objects are still "live". >> In my web application, just after a Tomcat startup, I have 2 instances >> of this class, both of which are "live". > > "Live" is a critical attribute here - unless a full GC (or two) is > done, unused classes and classloaders will still be present. Use > JConsole to trigger GCs, if needed. I haven't forced any full GCs (jconsole can't connect since I didn't enable JMX when I started my server) but I only see 2 live WebappClassLoaders (and 2 dead ones) after running this command: for x in 1 2 3 4 5 ; \ do echo running ; \ touch lib/log4j-1.2.15.jar ; \ ant quick-install ; \ sleep 20s ; \ done (Each touch/quick-install triggers an application reload) Before my stress test, this was the output of 'jmap -heap': (Hmm... didn't realize I was using -client in development... I should fix that!) Attaching to process ID 11255, please wait... Debugger attached successfully. Client compiler detected. JVM version is 1.5.0_13-b05 using thread-local object allocation. Mark Sweep Compact GC Heap Configuration: MinHeapFreeRatio = 40 MaxHeapFreeRatio = 70 MaxHeapSize = 67108864 (64.0MB) NewSize = 655360 (0.625MB) MaxNewSize = 4294901760 (4095.9375MB) OldSize = 1441792 (1.375MB) NewRatio = 12 SurvivorRatio = 8 PermSize = 8388608 (8.0MB) MaxPermSize = 67108864 (64.0MB) Heap Usage: New Generation (Eden + 1 Survivor Space): capacity = 4128768 (3.9375MB) used = 1943672 (1.8536300659179688MB) free = 2185096 (2.0838699340820312MB) 47.0763191344246% used Eden Space: capacity = 3670016 (3.5MB) used = 1606928 (1.5324859619140625MB) free = 2063088 (1.9675140380859375MB) 43.785313197544646% used - From Space: capacity = 458752 (0.4375MB) used = 336744 (0.32114410400390625MB) free = 122008 (0.11635589599609375MB) 73.40436662946429% used To Space: capacity = 458752 (0.4375MB) used = 0 (0.0MB) free = 458752 (0.4375MB) 0.0% used tenured generation: capacity = 54755328 (52.21875MB) used = 20156272 (19.222518920898438MB) free = 34599056 (32.99623107910156MB) 36.81152635959007% used Perm Generation: capacity = 32505856 (31.0MB) used = 23190896 (22.116561889648438MB) free = 9314960 (8.883438110351562MB) 71.343748031124% used After the test, I get this: Attaching to process ID 11255, please wait... Debugger attached successfully. Client compiler detected. JVM version is 1.5.0_13-b05 using thread-local object allocation. Mark Sweep Compact GC Heap Configuration: MinHeapFreeRatio = 40 MaxHeapFreeRatio = 70 MaxHeapSize = 67108864 (64.0MB) NewSize = 655360 (0.625MB) MaxNewSize = 4294901760 (4095.9375MB) OldSize = 1441792 (1.375MB) NewRatio = 12 SurvivorRatio = 8 PermSize = 8388608 (8.0MB) MaxPermSize = 67108864 (64.0MB) Heap Usage: New Generation (Eden + 1 Survivor Space): capacity = 3604480 (3.4375MB) used = 1326112 (1.264678955078125MB) free = 2278368 (2.172821044921875MB) 36.79066051136363% used Eden Space: capacity = 3211264 (3.0625MB) used = 1004312 (0.9577865600585938MB) free = 2206952 (2.1047134399414062MB) 31.274663185586736% used - From Space: capacity = 393216 (0.375MB) used = 321800 (0.30689239501953125MB) free = 71416 (0.06810760498046875MB) 81.83797200520833% used To Space: capacity = 393216 (0.375MB) used = 0 (0.0MB) free = 393216 (0.375MB) 0.0% used tenured generation: capacity = 47677440 (45.46875MB) used = 40365360 (38.49540710449219MB) free = 7312080 (6.9733428955078125MB) 84.66343830541237% used Perm Generation: capacity = 34078720 (32.5MB) used = 33963000 (32.38964080810547MB) free = 115720 (0.11035919189453125MB) 99.66043325570914% used I'm a little confused... the "configuration" seems to indicate that I've got an 8MB PermGen space, but then the Permanent Generation says it's 32.5MB. Let's try to force a full GC by using System.gc() from a little JSP file. Here's the heap description afterward: Attaching to process ID 11255, please wait... Debugger attached successfully. Client compiler detected. JVM version is 1.5.0_13-b05 using thread-local object allocation. Mark Sweep Compact GC Heap Configuration: MinHeapFreeRatio = 40 MaxHeapFreeRatio = 70 MaxHeapSize = 67108864 (64.0MB) NewSize = 655360 (0.625MB) MaxNewSize = 4294901760 (4095.9375MB) OldSize = 1441792 (1.375MB) NewRatio = 12 SurvivorRatio = 8 PermSize = 8388608 (8.0MB) MaxPermSize = 67108864 (64.0MB) Heap Usage: New Generation (Eden + 1 Survivor Space): capacity = 3604480 (3.4375MB) used = 357840 (0.3412628173828125MB) free = 3246640 (3.0962371826171875MB) 9.927645596590908% used Eden Space: capacity = 3211264 (3.0625MB) used = 357840 (0.3412628173828125MB) free = 2853424 (2.7212371826171875MB) 11.143275669642858% used - From Space: capacity = 393216 (0.375MB) used = 0 (0.0MB) free = 393216 (0.375MB) 0.0% used To Space: capacity = 393216 (0.375MB) used = 0 (0.0MB) free = 393216 (0.375MB) 0.0% used tenured generation: capacity = 47677440 (45.46875MB) used = 17904184 (17.07476043701172MB) free = 29773256 (28.39398956298828MB) 37.55273773088488% used Perm Generation: capacity = 20185088 (19.25MB) used = 20101336 (19.170127868652344MB) free = 83752 (0.07987213134765625MB) 99.58507983715504% used ... and checking for WebappClassLoader objects after that shows 2 live WebappClassLoaders none dead. Looks like my webapp is clean, at least when it first comes up. We don't have any weird stuff like Quartz, etc. and all our caching is done using Maps in the application scope or within a webapp-loaded class. I also have a pair of ServletContextListeners that shut down JULI and log4j as appropriate (if they're been loaded by the webapp and not a parent). I'm not sure if they actually help (and it doesn't matter since we never bounce our application in production without also bouncing Tomcat itself. I'd love some help interpreting the heap info I see above. Thanks! - -chris -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAknuR4sACgkQ9CaO5/Lv0PAnRgCgjHrQWJsj4hDG2ys9OcXE8ftf 8p8AoIVhWdvPJSTpldVCmsolEQe6K8wq =DW+t -----END PGP SIGNATURE----- --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
