Failing promption guarantee?

[James Nichols]

Hi,

I have two questions.

I'm pretty sure I'm on the right track with this, but I'm getting close to
pushing out a new release and would really love an extra set of eyes on this
problem.  The first is that I think I might be hitting the promotion
guarantee, as shown by this GC output below.  As you can see, both eden and
from are 100% full, but I'm pretty sure that it's all garbage, as evidenced
by the precipitous drop in the young and tenured generation.  Does the
output for the actual GC saying ParNew indicate that it was trying to do a
young collection, but ended up doing a full GC instead?  It also looks like
CMS would've helped out in this case.

157148.797: [GC {Heap before gc invocations=545:
 par new generation   total 1100288K, used 1100288K [0x00002aaab21b0000,
0x00002aaafedb0000, 0x00002aaafedb0000)
  eden space 943104K, 100% used [0x00002aaab21b0000, 0x00002aaaebab0000,
0x00002aaaebab0000)
  from space 157184K, 100% used [0x00002aaaf5430000, 0x00002aaafedb0000,
0x00002aaafedb0000)
  to   space 157184K,   0% used [0x00002aaaebab0000, 0x00002aaaebab0000,
0x00002aaaf5430000)
 tenured generation   total 2936832K, used 2014622K [0x00002aaafedb0000,
0x00002aabb21b0000, 0x00002aabb21b0000)
   the space 2936832K,  68% used [0x00002aaafedb0000, 0x00002aab79d17ba0,
0x00002aab79d17c00, 0x00002aabb21b0000)
 compacting perm gen  total 262144K, used 136065K [0x00002aabb21b0000,
0x00002aabc21b0000, 0x00002aabc21b0000)
   the space 262144K,  51% used [0x00002aabb21b0000, 0x00002aabba6906a0,
0x00002aabba690800, 0x00002aabc21b0000)
No shared spaces configured.
157148.797: [ParNew: 1100288K->1100288K(1100288K), 0.0000400
secs]157148.797: [Tenured: 2014622K->1135456K(2936832K), 17.1537650 secs]
3114910K->1135456K(4037120K)Heap after gc invocations=546:
 par new generation   total 1100288K, used 0K [0x00002aaab21b0000,
0x00002aaafedb0000, 0x00002aaafedb0000)
  eden space 943104K,   0% used [0x00002aaab21b0000, 0x00002aaab21b0000,
0x00002aaaebab0000)
  from space 157184K,   0% used [0x00002aaaf5430000, 0x00002aaaf5430000,
0x00002aaafedb0000)
  to   space 157184K,   0% used [0x00002aaaebab0000, 0x00002aaaebab0000,
0x00002aaaf5430000)
 tenured generation   total 2936832K, used 1135456K [0x00002aaafedb0000,
0x00002aabb21b0000, 0x00002aabb21b0000)
   the space 2936832K,  38% used [0x00002aaafedb0000, 0x00002aab44288078,
0x00002aab44288200, 0x00002aabb21b0000)
 compacting perm gen  total 262144K, used 136065K [0x00002aabb21b0000,
0x00002aabc21b0000, 0x00002aabc21b0000)
   the space 262144K,  51% used [0x00002aabb21b0000, 0x00002aabba6906a0,
0x00002aabba690800, 0x00002aabc21b0000)
No shared spaces configured.
}
, 17.1543400 secs]
Total time for which application threads were stopped: 17.2148700 seconds


Here are my JVM arguments:

JAVA_OPTS="-Xms4096m -Xmx4096m -XX:NewSize=1228M -XX:MaxNewSize=1228M
-XX:MaxTenuringThreshold=4 -XX:SurvivorRatio=6 -XX:+ScavengeBeforeFullGC
-XX:PermSize=256M -XX:MaxPermSize=256M  -XX:+UseParNewGC
-XX:ParallelGCThreads=3  -verbosegc -XX:+DisableExplicitGC
-XX:+PrintTenuringDistribution -XX:+PrintGCDetails -XX:+PrintGCTimeStamps
-XX:+PrintHeapAtGC -XX:+PrintGCApplicationConcurrentTime
-XX:+PrintGCApplicationStoppedTime -XX:+PrintClassHistogram
-Xloggc:/var/log/jboss/gc.dat -Dsun.net.client.defaultConnectTimeout=10000"



The second question is that I'm on JMV rev jdk1.5.0_12.  I see that rev 16
is out.  Is there a way to get a list of any GC bug fixes in this rev?
Also, has is there a way to gauge the stability of this rev know that it has
been in the wild for a while?  I'm just a little nervous to make the change
since I got burned pretty badly with like rev 08.

Jim
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