Unexpected Java 6 vs 8 GC performance difference

[Hughes,Corbin]

Jon,

Thanks for the interest. Hopefully this log will be more helpful. This is Java 7 with the -XX:-UseParallelOldGC flag. Perhaps notably, the PSYoungGen collections are even slower in Java 7 (regardless of whether or not the serial old collector is used).

Thanks,

Corbin

{Heap before GC invocations=456 (full 0):
 PSYoungGen      total 2091008K, used 2087456K [0x0000000780000000, 0x0000000800000000, 0x0000000800000000)
  eden space 2084864K, 100% used [0x0000000780000000,0x00000007ff400000,0x00000007ff400000)
  from space 6144K, 42% used [0x00000007ff400000,0x00000007ff688000,0x00000007ffa00000)
  to   space 6144K, 0% used [0x00000007ffa00000,0x00000007ffa00000,0x0000000800000000)
 PSOldGen        total 3145728K, used 2267941K [0x00000006c0000000, 0x0000000780000000, 0x0000000780000000)
  object space 3145728K, 72% used [0x00000006c0000000,0x000000074a6c9508,0x0000000780000000)
 PSPermGen       total 819200K, used 57100K [0x0000000680000000, 0x00000006b2000000, 0x00000006c0000000)
  object space 819200K, 6% used [0x0000000680000000,0x00000006837c3130,0x00000006b2000000)
1461.284: [GC
Desired survivor size 6291456 bytes, new threshold 1 (max 15)
 [PSYoungGen: 2087456K->1482K(2091008K)] 4355397K->2269463K(5236736K), 0.2986350 secs] [Times: user=0.34 sys=0.00, real=0.30 secs]
Heap after GC invocations=456 (full 0):
 PSYoungGen      total 2091008K, used 1482K [0x0000000780000000, 0x0000000800000000, 0x0000000800000000)
  eden space 2084864K, 0% used [0x0000000780000000,0x0000000780000000,0x00000007ff400000)
  from space 6144K, 24% used [0x00000007ffa00000,0x00000007ffb72928,0x0000000800000000)
  to   space 6144K, 0% used [0x00000007ff400000,0x00000007ff400000,0x00000007ffa00000)
 PSOldGen        total 3145728K, used 2267981K [0x00000006c0000000, 0x0000000780000000, 0x0000000780000000)
  object space 3145728K, 72% used [0x00000006c0000000,0x000000074a6d3528,0x0000000780000000)
 PSPermGen       total 819200K, used 57100K [0x0000000680000000, 0x00000006b2000000, 0x00000006c0000000)
  object space 819200K, 6% used [0x0000000680000000,0x00000006837c3130,0x00000006b2000000)
}
{Heap before GC invocations=457 (full 0):
 PSYoungGen      total 2091008K, used 2086346K [0x0000000780000000, 0x0000000800000000, 0x0000000800000000)
  eden space 2084864K, 100% used [0x0000000780000000,0x00000007ff400000,0x00000007ff400000)
  from space 6144K, 24% used [0x00000007ffa00000,0x00000007ffb72928,0x0000000800000000)
  to   space 6144K, 0% used [0x00000007ff400000,0x00000007ff400000,0x00000007ffa00000)
 PSOldGen        total 3145728K, used 2267981K [0x00000006c0000000, 0x0000000780000000, 0x0000000780000000)
  object space 3145728K, 72% used [0x00000006c0000000,0x000000074a6d3528,0x0000000780000000)
 PSPermGen       total 819200K, used 57100K [0x0000000680000000, 0x00000006b2000000, 0x00000006c0000000)
  object space 819200K, 6% used [0x0000000680000000,0x00000006837c3130,0x00000006b2000000)
1463.560: [GC
Desired survivor size 6291456 bytes, new threshold 1 (max 15)
 [PSYoungGen: 2086346K->3177K(2091008K)] 4354327K->2271183K(5236736K), 0.2974600 secs] [Times: user=0.33 sys=0.00, real=0.30 secs]
Heap after GC invocations=457 (full 0):
 PSYoungGen      total 2091008K, used 3177K [0x0000000780000000, 0x0000000800000000, 0x0000000800000000)
  eden space 2084864K, 0% used [0x0000000780000000,0x0000000780000000,0x00000007ff400000)
  from space 6144K, 51% used [0x00000007ff400000,0x00000007ff71a730,0x00000007ffa00000)
  to   space 6144K, 0% used [0x00000007ffa00000,0x00000007ffa00000,0x0000000800000000)
 PSOldGen        total 3145728K, used 2268005K [0x00000006c0000000, 0x0000000780000000, 0x0000000780000000)
  object space 3145728K, 72% used [0x00000006c0000000,0x000000074a6d9528,0x0000000780000000)
 PSPermGen       total 819200K, used 57100K [0x0000000680000000, 0x00000006b2000000, 0x00000006c0000000)
  object space 819200K, 6% used [0x0000000680000000,0x00000006837c3130,0x00000006b2000000)
}
{Heap before GC invocations=458 (full 0):
 PSYoungGen      total 2091008K, used 2088041K [0x0000000780000000, 0x0000000800000000, 0x0000000800000000)
  eden space 2084864K, 100% used [0x0000000780000000,0x00000007ff400000,0x00000007ff400000)
  from space 6144K, 51% used [0x00000007ff400000,0x00000007ff71a730,0x00000007ffa00000)
  to   space 6144K, 0% used [0x00000007ffa00000,0x00000007ffa00000,0x0000000800000000)
 PSOldGen        total 3145728K, used 2268005K [0x00000006c0000000, 0x0000000780000000, 0x0000000780000000)
  object space 3145728K, 72% used [0x00000006c0000000,0x000000074a6d9528,0x0000000780000000)
 PSPermGen       total 819200K, used 57100K [0x0000000680000000, 0x00000006b2000000, 0x00000006c0000000)
  object space 819200K, 6% used [0x0000000680000000,0x00000006837c31b0,0x00000006b2000000)
1465.998: [GC
Desired survivor size 6291456 bytes, new threshold 1 (max 15)
 [PSYoungGen: 2088041K->1456K(2091008K)] 4356047K->2269485K(5236736K), 0.2940590 secs] [Times: user=0.33 sys=0.00, real=0.29 secs]
Heap after GC invocations=458 (full 0):
 PSYoungGen      total 2091008K, used 1456K [0x0000000780000000, 0x0000000800000000, 0x0000000800000000)
  eden space 2084864K, 0% used [0x0000000780000000,0x0000000780000000,0x00000007ff400000)
  from space 6144K, 23% used [0x00000007ffa00000,0x00000007ffb6c188,0x0000000800000000)
  to   space 6144K, 0% used [0x00000007ff400000,0x00000007ff400000,0x00000007ffa00000)
 PSOldGen        total 3145728K, used 2268029K [0x00000006c0000000, 0x0000000780000000, 0x0000000780000000)
  object space 3145728K, 72% used [0x00000006c0000000,0x000000074a6df528,0x0000000780000000)
 PSPermGen       total 819200K, used 57100K [0x0000000680000000, 0x00000006b2000000, 0x00000006c0000000)
  object space 819200K, 6% used [0x0000000680000000,0x00000006837c31b0,0x00000006b2000000)
}


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