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2 Replies Latest reply: Feb 10, 2011 12:34 AM by PhHein RSS

GC: interpreting the log messages using -verbose:gc and PrintGCDetails

843798 Newbie
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Hello,

i have a webapp running in tomcat 4 and at some point in time the whole app starts running very slow. after some debugging and experiencing with VM settings, especial GC logging settings i saw that the consumed memory from NewGen is never free'd, and, if i understand correct, is not copy'd to OldGen. Are the new objects allocated in OldGen? The GC there is able to free memory everytime GC runs, but the time for that collection is very long, and i think the reason why our app runs so slow ...

Can anybody explain me the behaviour of the VM? (Java version: 1.4.2_06)

33249.940: [GC 33249.940: [DefNew: 409599K->409599K(460800K), 0.0000420 secs]33249.940: [Tenured: 192446K->193182K(409600K), 1.2274960 secs] 602046K->193182K(870400K), 1.2276930 secs]
33252.139: [GC 33252.139: [DefNew: 409599K->409599K(460800K), 0.0000430 secs]33252.139: [Tenured: 193182K->193633K(409600K), 1.5801410 secs] 602782K->193633K(870400K), 1.5803400 secs]
33255.535: [GC 33255.535: [DefNew: 409593K->409593K(460800K), 0.0000370 secs]33255.535: [Tenured: 193633K->191216K(409600K), 2.1173670 secs] 603226K->191216K(870400K), 2.1175360 secs]
33258.457: [GC 33258.457: [DefNew: 409599K->409599K(460800K), 0.0000400 secs]33258.457: [Tenured: 191216K->192107K(409600K), 1.1388990 secs] 600816K->192107K(870400K), 1.1390530 secs]

thx, Chris