frequent full GC: why?

[Anuj Lal]

Jdk version 1.5.0_16rev9
What can the cause of full gc back to back?.
We are seeing frequent full GC even though enough space there in old space as well as in perm space ?.
When new space fills up I expect only new gc but not FULL GC.

Old space is only 126 MB filled ( out of 194MB)
Permspace is only 129MB out of 215 ( max perm space is 256mb)

These is our setting
-Xms2410m -server -XX:CMSInitiatingOccupancyFraction=75 Xmx2410m -XX:NewSize=512M -XX:MaxNewSize=512M -XX:MaxTenuringThreshold=6 -XX:SurvivorRatio=5 -XX:TargetSurvivorRatio=80  -XX:MaxPermSize=256M -XX:ThreadStackSize=256 -verbose:gc -XX:+PrintGCTimeStamps -XX:+PrintClassHistogram -XX:+UseConcMarkSweepGC -XX:+UseParNewGC -XX:+CMSParallelRemarkEnabled -XX:+UseCMSCompactAtFullCollection -XX:CMSFullGCsBeforeCompaction=0 -XX:+HandlePromotionFailure  -XX:+UseCMSInitiatingOccupancyOnly -XX:CMSMarkStackSize=32M -XX:CodeCacheMinimumFreeSpace=2M -XX:ReservedCodeCacheSize=64M - -XX:CMSMaxAbortablePrecleanTime=1 -XX:+PrintGCDetails -XX:+PrintHeapAtGC -XX:+PrintTenuringDistribution -


1071256.659: [Full GC {Heap before gc invocations=4293:
 par new generation   total 449408K, used 380965K [0x4f800000, 0x6f800000, 0x6f800000)
  eden space 374528K,  99% used [0x4f800000, 0x66517448, 0x665c0000)
  from space 74880K,   9% used [0x665c0000, 0x66cb2318, 0x6aee0000)
  to   space 74880K,   0% used [0x6aee0000, 0x6aee0000, 0x6f800000)
 concurrent mark-sweep generation total 1943552K, used 141477K [0x6f800000, 0xe6200000, 0xe6400000)
 concurrent-mark-sweep perm gen total 215832K, used 129513K [0xe6400000, 0xf36c6000, 0xf6400000)
1071256.661: [CMS: 141477K->126065K(1943552K), 3.9483474 secs] 522443K->126065K(2392960K), [CMS Perm : 129513K->129487K(215832K)]Heap after gc invocations=4294:
 par new generation   total 449408K, used 0K [0x4f800000, 0x6f800000, 0x6f800000)
  eden space 374528K,   0% used [0x4f800000, 0x4f800000, 0x665c0000)
  from space 74880K,   0% used [0x665c0000, 0x665c0000, 0x6aee0000)
  to   space 74880K,   0% used [0x6aee0000, 0x6aee0000, 0x6f800000)
 concurrent mark-sweep generation total 1943552K, used 126065K [0x6f800000, 0xe6200000, 0xe6400000)
 concurrent-mark-sweep perm gen total 215832K, used 129487K [0xe6400000, 0xf36c6000, 0xf6400000)
}
, 3.9511002 secs]
1071289.014: [Full GC {Heap before gc invocations=4294:
 par new generation   total 449408K, used 129843K [0x4f800000, 0x6f800000, 0x6f800000)
  eden space 374528K,  34% used [0x4f800000, 0x576ccd88, 0x665c0000)
  from space 74880K,   0% used [0x665c0000, 0x665c0000, 0x6aee0000)
  to   space 74880K,   0% used [0x6aee0000, 0x6aee0000, 0x6f800000)
 concurrent mark-sweep generation total 1943552K, used 126065K [0x6f800000, 0xe6200000, 0xe6400000)
 concurrent-mark-sweep perm gen total 215832K, used 129496K [0xe6400000, 0xf36c6000, 0xf6400000)
1071289.016: [CMS[Unloading class sun.reflect.GeneratedSerializationConstructorAccessor1251]
[Unloading class sun.reflect.GeneratedMethodAccessor3111]
: 126065K->123793K(1943552K), 4.6073158 secs] 255908K->123793K(2392960K), [CMS Perm : 129496K->129483K(215832K)]Heap after gc invocations=4295:
 par new generation   total 449408K, used 0K [0x4f800000, 0x6f800000, 0x6f800000)
  eden space 374528K,   0% used [0x4f800000, 0x4f800000, 0x665c0000)
  from space 74880K,   0% used [0x665c0000, 0x665c0000, 0x6aee0000)
  to   space 74880K,   0% used [0x6aee0000, 0x6aee0000, 0x6f800000)
 concurrent mark-sweep generation total 1943552K, used 123793K [0x6f800000, 0xe6200000, 0xe6400000)
 concurrent-mark-sweep perm gen total 215832K, used 129483K [0xe6400000, 0xf36c6000, 0xf6400000)
}
, 4.6100803 secs]
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