Why always Full GC error messages?

[bcitsnm]

I keep getting these error messages on the server [Full GC 319126K->287809K(20963008K), 0.4774575 secs], [Full GC 70238K->26041K (20963008K), 0.0959407 secs], Full GC 1771135K->14296737K(20963008K), 520.1928051 secs. We have a physical server, which is installed with windows 2008 standard edition. The available physical memory is 16 GB and the allocated is 14 GB for the server. The usage is reaching up to 20 GB. I have to stop and start the "JBOSS" services manually by clicking a batch file. I have increased the MaxPermSize Allocated to 14336 m.

  This is what I am getting as checked on the GC information on the server. Could someone help me to identify and fix the problem?

S0C=8512.0 S1C=8512.0 S0U=0.0 S1U=48.6 EC=68160.0 EU=0.0 OC=20886336.0 OU =5348264.6 PC = 226672.0 PU = 140487.6 YGC = 17039 YGCT = 251.973 FGC = 10 FGCT = 1.068 GCT = 253.041

          Let me know if you require more information on the same.

[claudio4j]

The 14336mb for MaxPermSize is too big, if the machine has 16GB, you can roughly allocate the following. You also should leave some 20% to the operating system.

12GB for -XX:MaxSize

1GB for MaxPermSize

If the server regularly keeps consuming memory and needs frequent restarts, there is some code not releasing memory or consuming too much, this deserves some investigation, for example:

- memory dumps

- code profiling in a developer machine

- application performance monitoring

Understand that JVM tuning and code profiling involve a good time investigating where is the problem.