Last few days i am facing some Full Gc issues in my RedHat Linux Application Server with out having any load and sample gclog is shown below

2012-02-24T10:37:35.359+0530: 1194221.789: [Full GC 1194221.789: [Tenured: 1075903K->1075903K(1075904K), 2.6399480 secs] 1560050K->1211377K(1560064K), [Perm : 143373K->143373K(143616K)], 2.6400630 secs] [Times: user=2.63 sys=0.01, real=2.64 secs] 2012-02-24T10:37:47.452+0530: 1194233.883: [Full GC 1194233.883: [Tenured: 1075903K->1075903K(1075904K), 2.7868630 secs] 1559508K->1215479K(1560064K), [Perm : 143380K->143380K(143616K)], 2.7869970 secs] [Times: user=2.79 sys=0.00, real=2.79 secs]

Entries in Console.log while taking thread dumb shown below

Heap def new generation total 484160K, used 307665K [0x826a0000, 0xa33f0000, 0xa33f0000)

eden space 430400K, 71% used [0x826a0000, 0x95314460, 0x9caf0000)

from space 53760K, 0% used [0x9caf0000, 0x9caf0000, 0x9ff70000)

to space 53760K, 0% used [0x9ff70000, 0x9ff70000, 0xa33f0000)

tenured generation total 1075904K, used 1075904K [0xa33f0000, 0xe4ea0000, 0xe4ea0000)

the space 1075904K, 100% used [0xa33f0000, 0xe4ea0000, 0xe4ea0000, 0xe4ea0000)

compacting perm gen total 137728K, used 137662K [0xe4ea0000, 0xed520000, 0xf4ea0000)

the space 137728K, 99% used [0xe4ea0000, 0xed50fae0, 0xed50fc00, 0xed520000)

No shared spaces configured.

Please give me certain tips to monitor the gclog and give a basic knowledge about Full GC.Also please suggest some document or tutorial link to understand this concept thoroughly.And also tell me What are the parameters i have to watch before increasing the heap size..???


Garbage collection is not an "issue", it is a core java feature.

This runs periodically, even if there is no activity - and yes, the full GC takes a long time, but that's why it only happens once every hour or so.

See the official Oracle/Sun documentation for J2SE for details on how it works and how to configure it

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