Trying to bump up tenuring threshold - failing

[Kobe Bryant]

I am using oracle jdk 1.6 (latest build) in 64 bit mode. The system
enocuntering
too much promotions out of young gen; this makes tenuring threshold 1.

So I thought i must increase young gen size. I did incrementally from 2GB
heap to 3GB heap
and with each increment I increase young gen size progressively:


export MEMORY_OPTIONS="-Xmx3g -Xms3g" -XX:MaxNewSize=830m -XX:NewSize=830m
-XX:SurvivorRatio=6 -XX:PermSize=764m -XX:MaxPermSize=764m"
export ADDITIONAL_GC_OPTIONS="-XX:+PrintGCDateStamps
-XX:+PrintTenuringDistribution -XX:+PrintAdaptiveSizePolicy
-XX:+PrintGCApplicationStoppedTime -XX:+PrintGCApplicationConcurrentTime"
export GC_OPTIONS="-verbose:gc -XX:+PrintGCTimeStamps -XX:+PrintGCDetails
-XX:+PrintHeapAtGC -Xloggc:log34221.log -XX:+DisableExplicitGC
${ADDITIONAL_GC_OPTIONS}"


But tenuring threshold start at 7 and then go to 1:
   $ grep "new threshold" log34421.log
   Desired survivor size 108789760 bytes, new threshold 7 (max 15)
   Desired survivor size 108789760 bytes, new threshold 7 (max 15)
   Desired survivor size 108789760 bytes, new threshold 6 (max 15)
   Desired survivor size 108789760 bytes, new threshold 5 (max 15)
   Desired survivor size 108789760 bytes, new threshold 4 (max 15)
   Desired survivor size 108789760 bytes, new threshold 3 (max 15)
   Desired survivor size 108789760 bytes, new threshold 2 (max 15)
   Desired survivor size 108789760 bytes, new threshold 1 (max 15)
   Desired survivor size 108789760 bytes, new threshold 1 (max 15)
   Desired survivor size 108789760 bytes, new threshold 1 (max 15)
   ...

How do I keep tenuring threshold at 3 or 4?

Also, in one iteration, the application stop time due to gc is listed as
          Application time: 78.8894050 seconds

This mean that GC threads suspended appliction threads for 78s??

A section of log shown here:

{Heap before GC invocations=1878 (full 22):
 PSYoungGen      total 743680K, used 741582K [0x00000007cc200000,
0x0000000800000000, 0x0000000800000000)
  eden space 637440K, 100% used
[0x00000007cc200000,0x00000007f3080000,0x00000007f3080000)
  from space 106240K, 98% used
[0x00000007f3080000,0x00000007f96338c0,0x00000007f9840000)
  to   space 106240K, 0% used
[0x00000007f9840000,0x00000007f9840000,0x0000000800000000)
 PSOldGen        total 2295808K, used 2071638K [0x0000000740000000,
0x00000007cc200000, 0x00000007cc200000)
  object space 2295808K, 90% used
[0x0000000740000000,0x00000007be715978,0x00000007cc200000)
 PSPermGen       total 782336K, used 544637K [0x0000000710400000,
0x0000000740000000, 0x0000000740000000)
  object space 782336K, 69% used
[0x0000000710400000,0x00000007317df490,0x0000000740000000)
2012-06-28T14:39:55.640-0400: 131078.967:
[GCAdaptiveSizePolicy::compute_survivor_space_size_and_thresh:  survived:
78129760  promoted: 13171824  overflow: falseAdaptiveSizeStart: 131079.039
collection: 1878
  avg_survived_padded_avg: 158664864.000000  avg_promoted_padded_avg:
30081980.000000  avg_pretenured_padded_avg: 0.000000  tenuring_thresh: 1
 target_size: 108789760
Desired survivor size 108789760 bytes, new threshold 1 (max 15)
PSAdaptiveSizePolicy::compute_generation_free_space: costs minor_time:
0.001379 major_cost: 0.000657 mutator_cost: 0.997964 throughput_goal:
0.990000 live_space: 2181788672 free_space: 1291321344 old_promo_size:
654835712 old_eden_size: 636485632 desired_promo_size: 654835712
desired_eden_size: 636485632
AdaptiveSizePolicy::survivor space sizes: collection: 1878 (108789760,
108789760) -> (108789760, 108789760)
AdaptiveSizeStop: collection: 1878
 [PSYoungGen: 741582K->76298K(743680K)] 2813220K->2160800K(3039488K),
0.0723130 secs] [Times: user=0.27 sys=0.00, real=0.07 secs]
Heap after GC invocations=1878 (full 22):
 PSYoungGen      total 743680K, used 76298K [0x00000007cc200000,
0x0000000800000000, 0x0000000800000000)
  eden space 637440K, 0% used
[0x00000007cc200000,0x00000007cc200000,0x00000007f3080000)
  from space 106240K, 71% used
[0x00000007f9840000,0x00000007fe2c2a60,0x0000000800000000)
  to   space 106240K, 0% used
[0x00000007f3080000,0x00000007f3080000,0x00000007f9840000)
 PSOldGen        total 2295808K, used 2084501K [0x0000000740000000,
0x00000007cc200000, 0x00000007cc200000)
  object space 2295808K, 90% used
[0x0000000740000000,0x00000007bf3a55e8,0x00000007cc200000)
 PSPermGen       total 782336K, used 544637K [0x0000000710400000,
0x0000000740000000, 0x0000000740000000)
  object space 782336K, 69% used
[0x0000000710400000,0x00000007317df490,0x0000000740000000)
}
Total time for which application threads were stopped: 0.0763960 seconds
Application time: 78.8894050 seconds

thank,

/kobe
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