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From Jonathan Ellis <jbel...@gmail.com>
Subject Re: GC performance in 1.0.x
Date Thu, 23 Feb 2012 20:13:38 GMT
30ms pauses are on the low side of normal for a 800MB young gen under
parnew.  We're not going to be able to get rid of those, although it
looks like you're seeing objects in the young gen die *very* quickly,
so cutting that to say 200MB might give you shorter (and more
frequent) pauses for the young gen.

If you can mail me the entire log file I can look to see if there were
any stop-the-world full collections, which is where you'd see the
multi-second pauses that we really want to avoid.

On Sat, Feb 18, 2012 at 12:17 PM, Edward Capriolo <edlinuxguru@gmail.com> wrote:
> MAX_HEAP_SIZE="9G"
> HEAP_NEWSIZE="800M"
>
> 2 socket quad core
> 44GB RAM
> Cassandra 1.0.7
>
> [edward@cdbla120 cassandra]$ free -g
>             total       used       free     shared    buffers     cached
> Mem:            43         34          8          0          0
        25
> -/+ buffers/cache:          8         34
> Swap:            0          0          0
>
> # GC logging options -- uncomment to enable
> JVM_OPTS="$JVM_OPTS -XX:+PrintGCDetails"
> JVM_OPTS="$JVM_OPTS -XX:+PrintGCDateStamps"
> JVM_OPTS="$JVM_OPTS -XX:+PrintHeapAtGC"
> JVM_OPTS="$JVM_OPTS -XX:+PrintTenuringDistribution"
> JVM_OPTS="$JVM_OPTS -XX:+PrintGCApplicationStoppedTime"
> JVM_OPTS="$JVM_OPTS -XX:+PrintPromotionFailure"
> JVM_OPTS="$JVM_OPTS -XX:PrintFLSStatistics=1"
> JVM_OPTS="$JVM_OPTS -Xloggc:/var/log/cassandra/gc-`date +%s`.log"
> JVM_OPTS="$JVM_OPTS -verbose:gc"
> JVM_OPTS="$JVM_OPTS -XX:+PrintSafepointStatistics"
>
> Three major column families using compression on two out of three. I
> never really watched the gc logs too much before since i was disk
> bound, but in this case I have all the data in main memory so limiting
> pauses would be big for me.
>
> I see a good number of these:
>
> Total time for which application threads were stopped: 0.0301370 seconds
> Total time for which application threads were stopped: 0.0046390 seconds
>
> [edward@cdbla120 cassandra]$ tail -400 gc-1329578417.log
> Total Free Space: 637346254
> Max   Chunk Size: 138752484
> Number of Blocks: 482066
> Av.  Block  Size: 1322
> Tree      Height: 34
> Before GC:
> Statistics for BinaryTreeDictionary:
> ------------------------------------
> Total Free Space: 1829376
> Max   Chunk Size: 1829376
> Number of Blocks: 1
> Av.  Block  Size: 1829376
> Tree      Height: 1
> 10516.947: [ParNew
> Desired survivor size 41943040 bytes, new threshold 1 (max 1)
> - age   1:      48752 bytes,      48752 total
> : 7689K->5164K(737280K), 0.0173210 secs] 3594487K->3597704K(9355264K)After GC:
> Statistics for BinaryTreeDictionary:
> ------------------------------------
> Total Free Space: 636661736
> Max   Chunk Size: 138752484
> Number of Blocks: 481773
> Av.  Block  Size: 1321
> Tree      Height: 34
> After GC:
> Statistics for BinaryTreeDictionary:
> ------------------------------------
> Total Free Space: 1829376
> Max   Chunk Size: 1829376
> Number of Blocks: 1
> Av.  Block  Size: 1829376
> Tree      Height: 1
> , 0.0204840 secs] [Times: user=0.19 sys=0.00, real=0.02 secs]
> Heap after GC invocations=3856 (full 4):
>  par new generation   total 737280K, used 5164K [0x00000005bae00000,
> 0x00000005ece00000, 0x00000005ece00000)
>  eden space 655360K,   0% used [0x00000005bae00000,
> 0x00000005bae00000, 0x00000005e2e00000)
>  from space 81920K,   6% used [0x00000005e2e00000,
> 0x00000005e330b030, 0x00000005e7e00000)
>  to   space 81920K,   0% used [0x00000005e7e00000,
> 0x00000005e7e00000, 0x00000005ece00000)
>  concurrent mark-sweep generation total 8617984K, used 3592540K
> [0x00000005ece00000, 0x00000007fae00000, 0x00000007fae00000)
>  concurrent-mark-sweep perm gen total 35796K, used 21382K
> [0x00000007fae00000, 0x00000007fd0f5000, 0x0000000800000000)
> }
> Total time for which application threads were stopped: 0.0251700 seconds
> Total time for which application threads were stopped: 0.0046210 seconds
> {Heap before GC invocations=3856 (full 4):
>  par new generation   total 737280K, used 660839K [0x00000005bae00000,
> 0x00000005ece00000, 0x00000005ece00000)
>  eden space 655360K, 100% used [0x00000005bae00000,
> 0x00000005e2e00000, 0x00000005e2e00000)
>  from space 81920K,   6% used [0x00000005e2e00000,
> 0x00000005e3359df0, 0x00000005e7e00000)
>  to   space 81920K,   0% used [0x00000005e7e00000,
> 0x00000005e7e00000, 0x00000005ece00000)
>  concurrent mark-sweep generation total 8617984K, used 3592540K
> [0x00000005ece00000, 0x00000007fae00000, 0x00000007fae00000)
>  concurrent-mark-sweep perm gen total 35796K, used 21382K
> [0x00000007fae00000, 0x00000007fd0f5000, 0x0000000800000000)
> 2012-02-18T13:15:35.980-0500: 10518.844: [GC Before GC:
> Statistics for BinaryTreeDictionary:
> ------------------------------------
> Total Free Space: 636661736
> Max   Chunk Size: 138752484
> Number of Blocks: 481773
> Av.  Block  Size: 1321
> Tree      Height: 34
> Before GC:
> Statistics for BinaryTreeDictionary:
> ------------------------------------
> Total Free Space: 1829376
> Max   Chunk Size: 1829376
> Number of Blocks: 1
> Av.  Block  Size: 1829376
> Tree      Height: 1
> 10518.846: [ParNew
> Desired survivor size 41943040 bytes, new threshold 1 (max 1)
> - age   1:    7128016 bytes,    7128016 total
> : 660839K->7853K(737280K), 0.0176930 secs] 4253380K->3600423K(9355264K)After GC:
> Statistics for BinaryTreeDictionary:
> ------------------------------------
> Total Free Space: 636661235
> Max   Chunk Size: 138752484
> Number of Blocks: 481772
> Av.  Block  Size: 1321
> Tree      Height: 34
> After GC:
> Statistics for BinaryTreeDictionary:
> ------------------------------------
> Total Free Space: 1829376
> Max   Chunk Size: 1829376
> Number of Blocks: 1
> Av.  Block  Size: 1829376
> Tree      Height: 1
> , 0.0210680 secs] [Times: user=0.18 sys=0.00, real=0.02 secs]
> Heap after GC invocations=3857 (full 4):
>  par new generation   total 737280K, used 7853K [0x00000005bae00000,
> 0x00000005ece00000, 0x00000005ece00000)
>  eden space 655360K,   0% used [0x00000005bae00000,
> 0x00000005bae00000, 0x00000005e2e00000)
>  from space 81920K,   9% used [0x00000005e7e00000,
> 0x00000005e85ab660, 0x00000005ece00000)
>  to   space 81920K,   0% used [0x00000005e2e00000,
> 0x00000005e2e00000, 0x00000005e7e00000)
>  concurrent mark-sweep generation total 8617984K, used 3592570K
> [0x00000005ece00000, 0x00000007fae00000, 0x00000007fae00000)
>  concurrent-mark-sweep perm gen total 35796K, used 21382K
> [0x00000007fae00000, 0x00000007fd0f5000, 0x0000000800000000)
> }
> Total time for which application threads were stopped: 0.0256030 seconds
> {Heap before GC invocations=3857 (full 4):
>  par new generation   total 737280K, used 7876K [0x00000005bae00000,
> 0x00000005ece00000, 0x00000005ece00000)
>  eden space 655360K,   0% used [0x00000005bae00000,
> 0x00000005bae05ac0, 0x00000005e2e00000)
>  from space 81920K,   9% used [0x00000005e7e00000,
> 0x00000005e85ab660, 0x00000005ece00000)
>  to   space 81920K,   0% used [0x00000005e2e00000,
> 0x00000005e2e00000, 0x00000005e7e00000)
>  concurrent mark-sweep generation total 8617984K, used 3592570K
> [0x00000005ece00000, 0x00000007fae00000, 0x00000007fae00000)
>  concurrent-mark-sweep perm gen total 35796K, used 21382K
> [0x00000007fae00000, 0x00000007fd0f5000, 0x0000000800000000)
> 2012-02-18T13:15:36.006-0500: 10518.870: [GC Before GC:
> Statistics for BinaryTreeDictionary:
> ------------------------------------
> Total Free Space: 636661235
> Max   Chunk Size: 138752484
> Number of Blocks: 481772
> Av.  Block  Size: 1321
> Tree      Height: 34
> Before GC:
> Statistics for BinaryTreeDictionary:
> ------------------------------------
> Total Free Space: 1829376
> Max   Chunk Size: 1829376
> Number of Blocks: 1
> Av.  Block  Size: 1829376
> Tree      Height: 1
> 10518.871: [ParNew
> Desired survivor size 41943040 bytes, new threshold 1 (max 1)
> - age   1:       4912 bytes,       4912 total
> : 7876K->2197K(737280K), 0.0168170 secs] 3600446K->3601858K(9355264K)After GC:
> Statistics for BinaryTreeDictionary:
> ------------------------------------
> Total Free Space: 635807044
> Max   Chunk Size: 138752484
> Number of Blocks: 481304
> Av.  Block  Size: 1321
> Tree      Height: 34
> After GC:
> Statistics for BinaryTreeDictionary:
> ------------------------------------
> Total Free Space: 1829376
> Max   Chunk Size: 1829376
> Number of Blocks: 1
> Av.  Block  Size: 1829376
> Tree      Height: 1
> , 0.0199700 secs] [Times: user=0.19 sys=0.00, real=0.02 secs]
> Heap after GC invocations=3858 (full 4):
>  par new generation   total 737280K, used 2197K [0x00000005bae00000,
> 0x00000005ece00000, 0x00000005ece00000)
>  eden space 655360K,   0% used [0x00000005bae00000,
> 0x00000005bae00000, 0x00000005e2e00000)
>  from space 81920K,   2% used [0x00000005e2e00000,
> 0x00000005e3025410, 0x00000005e7e00000)
>  to   space 81920K,   0% used [0x00000005e7e00000,
> 0x00000005e7e00000, 0x00000005ece00000)
>  concurrent mark-sweep generation total 8617984K, used 3599661K
> [0x00000005ece00000, 0x00000007fae00000, 0x00000007fae00000)
>  concurrent-mark-sweep perm gen total 35796K, used 21382K
> [0x00000007fae00000, 0x00000007fd0f5000, 0x0000000800000000)
> }
> Total time for which application threads were stopped: 0.0261540 seconds
> {Heap before GC invocations=3858 (full 4):
>  par new generation   total 737280K, used 657515K [0x00000005bae00000,
> 0x00000005ece00000, 0x00000005ece00000)
>  eden space 655360K,  99% used [0x00000005bae00000,
> 0x00000005e2df5b20, 0x00000005e2e00000)
>  from space 81920K,   2% used [0x00000005e2e00000,
> 0x00000005e3025410, 0x00000005e7e00000)
>  to   space 81920K,   0% used [0x00000005e7e00000,
> 0x00000005e7e00000, 0x00000005ece00000)
>  concurrent mark-sweep generation total 8617984K, used 3599661K
> [0x00000005ece00000, 0x00000007fae00000, 0x00000007fae00000)
>  concurrent-mark-sweep perm gen total 35796K, used 21382K
> [0x00000007fae00000, 0x00000007fd0f5000, 0x0000000800000000)
> 2012-02-18T13:15:39.918-0500: 10522.782: [GC Before GC:
> Statistics for BinaryTreeDictionary:
> ------------------------------------
> Total Free Space: 635807044
> Max   Chunk Size: 138752484
> Number of Blocks: 481304
> Av.  Block  Size: 1321
> Tree      Height: 34
> Before GC:
> Statistics for BinaryTreeDictionary:
> ------------------------------------
> Total Free Space: 1829376
> Max   Chunk Size: 1829376
> Number of Blocks: 1
> Av.  Block  Size: 1829376
> Tree      Height: 1
> 10522.784: [ParNew
> Desired survivor size 41943040 bytes, new threshold 1 (max 1)
> - age   1:   18138696 bytes,   18138696 total
> : 657515K->18303K(737280K), 0.0225670 secs]
> 4257177K->3617966K(9355264K)After GC:
> Statistics for BinaryTreeDictionary:
> ------------------------------------
> Total Free Space: 635807044
> Max   Chunk Size: 138752484
> Number of Blocks: 481304
> Av.  Block  Size: 1321
> Tree      Height: 34
> After GC:
> Statistics for BinaryTreeDictionary:
> ------------------------------------
> Total Free Space: 1829376
> Max   Chunk Size: 1829376
> Number of Blocks: 1
> Av.  Block  Size: 1829376
> Tree      Height: 1
> , 0.0259020 secs] [Times: user=0.25 sys=0.00, real=0.03 secs]
> Heap after GC invocations=3859 (full 4):
>  par new generation   total 737280K, used 18303K [0x00000005bae00000,
> 0x00000005ece00000, 0x00000005ece00000)
>  eden space 655360K,   0% used [0x00000005bae00000,
> 0x00000005bae00000, 0x00000005e2e00000)
>  from space 81920K,  22% used [0x00000005e7e00000,
> 0x00000005e8fdffa8, 0x00000005ece00000)
>  to   space 81920K,   0% used [0x00000005e2e00000,
> 0x00000005e2e00000, 0x00000005e7e00000)
>  concurrent mark-sweep generation total 8617984K, used 3599662K
> [0x00000005ece00000, 0x00000007fae00000, 0x00000007fae00000)
>  concurrent-mark-sweep perm gen total 35796K, used 21382K
> [0x00000007fae00000, 0x00000007fd0f5000, 0x0000000800000000)
> }
> Total time for which application threads were stopped: 0.0310430 seconds
> Total time for which application threads were stopped: 0.0044970 seconds
> {Heap before GC invocations=3859 (full 4):
>  par new generation   total 737280K, used 673663K [0x00000005bae00000,
> 0x00000005ece00000, 0x00000005ece00000)
>  eden space 655360K, 100% used [0x00000005bae00000,
> 0x00000005e2e00000, 0x00000005e2e00000)
>  from space 81920K,  22% used [0x00000005e7e00000,
> 0x00000005e8fdffa8, 0x00000005ece00000)
>  to   space 81920K,   0% used [0x00000005e2e00000,
> 0x00000005e2e00000, 0x00000005e7e00000)
>  concurrent mark-sweep generation total 8617984K, used 3599662K
> [0x00000005ece00000, 0x00000007fae00000, 0x00000007fae00000)
>  concurrent-mark-sweep perm gen total 35796K, used 21382K
> [0x00000007fae00000, 0x00000007fd0f5000, 0x0000000800000000)
> 2012-02-18T13:15:43.662-0500: 10526.526: [GC Before GC:
> Statistics for BinaryTreeDictionary:
> ------------------------------------
> Total Free Space: 635807044
> Max   Chunk Size: 138752484
> Number of Blocks: 481304
> Av.  Block  Size: 1321
> Tree      Height: 34
> Before GC:
> Statistics for BinaryTreeDictionary:
> ------------------------------------
> Total Free Space: 1829376
> Max   Chunk Size: 1829376
> Number of Blocks: 1
> Av.  Block  Size: 1829376
> Tree      Height: 1
> 10526.528: [ParNew
> Desired survivor size 41943040 bytes, new threshold 1 (max 1)
> - age   1:    6231016 bytes,    6231016 total
> : 673663K->9643K(737280K), 0.0313290 secs] 4273326K->3621439K(9355264K)After GC:
> Statistics for BinaryTreeDictionary:
> ------------------------------------
> Total Free Space: 634281586
> Max   Chunk Size: 138752484
> Number of Blocks: 480350
> Av.  Block  Size: 1320
> Tree      Height: 34
> After GC:
> Statistics for BinaryTreeDictionary:
> ------------------------------------
> Total Free Space: 1829376
> Max   Chunk Size: 1829376
> Number of Blocks: 1
> Av.  Block  Size: 1829376
> Tree      Height: 1
> , 0.0347120 secs] [Times: user=0.31 sys=0.00, real=0.03 secs]
> Heap after GC invocations=3860 (full 4):
>  par new generation   total 737280K, used 9643K [0x00000005bae00000,
> 0x00000005ece00000, 0x00000005ece00000)
>  eden space 655360K,   0% used [0x00000005bae00000,
> 0x00000005bae00000, 0x00000005e2e00000)
>  from space 81920K,  11% used [0x00000005e2e00000,
> 0x00000005e376ade8, 0x00000005e7e00000)
>  to   space 81920K,   0% used [0x00000005e7e00000,
> 0x00000005e7e00000, 0x00000005ece00000)
>  concurrent mark-sweep generation total 8617984K, used 3611796K
> [0x00000005ece00000, 0x00000007fae00000, 0x00000007fae00000)
>  concurrent-mark-sweep perm gen total 35796K, used 21382K
> [0x00000007fae00000, 0x00000007fd0f5000, 0x0000000800000000)
> }
> Total time for which application threads were stopped: 0.0398640 seconds
> {Heap before GC invocations=3860 (full 4):
>  par new generation   total 737280K, used 664966K [0x00000005bae00000,
> 0x00000005ece00000, 0x00000005ece00000)
>  eden space 655360K,  99% used [0x00000005bae00000,
> 0x00000005e2df6be8, 0x00000005e2e00000)
>  from space 81920K,  11% used [0x00000005e2e00000,
> 0x00000005e376ade8, 0x00000005e7e00000)
>  to   space 81920K,   0% used [0x00000005e7e00000,
> 0x00000005e7e00000, 0x00000005ece00000)
>  concurrent mark-sweep generation total 8617984K, used 3611796K
> [0x00000005ece00000, 0x00000007fae00000, 0x00000007fae00000)
>  concurrent-mark-sweep perm gen total 35796K, used 21382K
> [0x00000007fae00000, 0x00000007fd0f5000, 0x0000000800000000)
> 2012-02-18T13:15:46.806-0500: 10529.671: [GC Before GC:
> Statistics for BinaryTreeDictionary:
> ------------------------------------
> Total Free Space: 634281586
> Max   Chunk Size: 138752484
> Number of Blocks: 480350
> Av.  Block  Size: 1320
> Tree      Height: 34
> Before GC:
> Statistics for BinaryTreeDictionary:
> ------------------------------------
> Total Free Space: 1829376
> Max   Chunk Size: 1829376
> Number of Blocks: 1
> Av.  Block  Size: 1829376
> Tree      Height: 1
> 10529.672: [ParNew
> Desired survivor size 41943040 bytes, new threshold 1 (max 1)
> - age   1:    5578880 bytes,    5578880 total
> : 664966K->8084K(737280K), 0.0217310 secs] 4276762K->3624063K(9355264K)After GC:
> Statistics for BinaryTreeDictionary:
> ------------------------------------
> Total Free Space: 633726004
> Max   Chunk Size: 138752484
> Number of Blocks: 480114
> Av.  Block  Size: 1319
> Tree      Height: 34
> After GC:
> Statistics for BinaryTreeDictionary:
> ------------------------------------
> Total Free Space: 1829376
> Max   Chunk Size: 1829376
> Number of Blocks: 1
> Av.  Block  Size: 1829376
> Tree      Height: 1
> , 0.0251170 secs] [Times: user=0.22 sys=0.00, real=0.03 secs]
> Heap after GC invocations=3861 (full 4):
>  par new generation   total 737280K, used 8084K [0x00000005bae00000,
> 0x00000005ece00000, 0x00000005ece00000)
>  eden space 655360K,   0% used [0x00000005bae00000,
> 0x00000005bae00000, 0x00000005e2e00000)
>  from space 81920K,   9% used [0x00000005e7e00000,
> 0x00000005e85e52f8, 0x00000005ece00000)
>  to   space 81920K,   0% used [0x00000005e2e00000,
> 0x00000005e2e00000, 0x00000005e7e00000)
>  concurrent mark-sweep generation total 8617984K, used 3615978K
> [0x00000005ece00000, 0x00000007fae00000, 0x00000007fae00000)
>  concurrent-mark-sweep perm gen total 35796K, used 21382K
> [0x00000007fae00000, 0x00000007fd0f5000, 0x0000000800000000)
> }
> Total time for which application threads were stopped: 0.0301370 seconds
> Total time for which application threads were stopped: 0.0046390 seconds
> {Heap before GC invocations=3861 (full 4):
>  par new generation   total 737280K, used 663583K [0x00000005bae00000,
> 0x00000005ece00000, 0x00000005ece00000)
>  eden space 655360K, 100% used [0x00000005bae00000,
> 0x00000005e2e00000, 0x00000005e2e00000)
>  from space 81920K,  10% used [0x00000005e7e00000,
> 0x00000005e8607de8, 0x00000005ece00000)
>  to   space 81920K,   0% used [0x00000005e2e00000,
> 0x00000005e2e00000, 0x00000005e7e00000)
>  concurrent mark-sweep generation total 8617984K, used 3615978K
> [0x00000005ece00000, 0x00000007fae00000, 0x00000007fae00000)
>  concurrent-mark-sweep perm gen total 35796K, used 21382K
> [0x00000007fae00000, 0x00000007fd0f5000, 0x0000000800000000)
> 2012-02-18T13:15:49.225-0500: 10532.089: [GC Before GC:
> Statistics for BinaryTreeDictionary:
> ------------------------------------
> Total Free Space: 633726004
> Max   Chunk Size: 138752484
> Number of Blocks: 480114
> Av.  Block  Size: 1319
> Tree      Height: 34
> Before GC:
> Statistics for BinaryTreeDictionary:
> ------------------------------------
> Total Free Space: 1829376
> Max   Chunk Size: 1829376
> Number of Blocks: 1
> Av.  Block  Size: 1829376
> Tree      Height: 1
> 10532.099: [ParNew
> Desired survivor size 41943040 bytes, new threshold 1 (max 1)
> - age   1:    4626680 bytes,    4626680 total
> : 663583K->7027K(737280K), 0.0214590 secs] 4279561K->3626859K(9355264K)After GC:
> Statistics for BinaryTreeDictionary:
> ------------------------------------
> Total Free Space: 633246817
> Max   Chunk Size: 138752484
> Number of Blocks: 479921
> Av.  Block  Size: 1319
> Tree      Height: 34
> After GC:
> Statistics for BinaryTreeDictionary:
> ------------------------------------
> Total Free Space: 1829376
> Max   Chunk Size: 1829376
> Number of Blocks: 1
> Av.  Block  Size: 1829376
> Tree      Height: 1
> , 0.0248210 secs] [Times: user=0.21 sys=0.00, real=0.03 secs]
> Heap after GC invocations=3862 (full 4):
>  par new generation   total 737280K, used 7027K [0x00000005bae00000,
> 0x00000005ece00000, 0x00000005ece00000)
>  eden space 655360K,   0% used [0x00000005bae00000,
> 0x00000005bae00000, 0x00000005e2e00000)
>  from space 81920K,   8% used [0x00000005e2e00000,
> 0x00000005e34dcd88, 0x00000005e7e00000)
>  to   space 81920K,   0% used [0x00000005e7e00000,
> 0x00000005e7e00000, 0x00000005ece00000)
>  concurrent mark-sweep generation total 8617984K, used 3619831K
> [0x00000005ece00000, 0x00000007fae00000, 0x00000007fae00000)
>  concurrent-mark-sweep perm gen total 35796K, used 21382K
> [0x00000007fae00000, 0x00000007fd0f5000, 0x0000000800000000)
> }
> Total time for which application threads were stopped: 0.0374180 seconds
> {Heap before GC invocations=3862 (full 4):
>  par new generation   total 737280K, used 662376K [0x00000005bae00000,
> 0x00000005ece00000, 0x00000005ece00000)
>  eden space 655360K,  99% used [0x00000005bae00000,
> 0x00000005e2dfd2b8, 0x00000005e2e00000)
>  from space 81920K,   8% used [0x00000005e2e00000,
> 0x00000005e34dcd88, 0x00000005e7e00000)
>  to   space 81920K,   0% used [0x00000005e7e00000,
> 0x00000005e7e00000, 0x00000005ece00000)
>  concurrent mark-sweep generation total 8617984K, used 3619831K
> [0x00000005ece00000, 0x00000007fae00000, 0x00000007fae00000)
>  concurrent-mark-sweep perm gen total 35796K, used 21382K
> [0x00000007fae00000, 0x00000007fd0f5000, 0x0000000800000000)
> 2012-02-18T13:15:52.121-0500: 10534.985: [GC Before GC:
> Statistics for BinaryTreeDictionary:
> ------------------------------------
> Total Free Space: 633246817
> Max   Chunk Size: 138752484
> Number of Blocks: 479921
> Av.  Block  Size: 1319
> Tree      Height: 34
> Before GC:
> Statistics for BinaryTreeDictionary:
> ------------------------------------
> Total Free Space: 1829376
> Max   Chunk Size: 1829376
> Number of Blocks: 1
> Av.  Block  Size: 1829376
> Tree      Height: 1
> 10534.987: [ParNew
> Desired survivor size 41943040 bytes, new threshold 1 (max 1)
> - age   1:    8678968 bytes,    8678968 total
> : 662376K->9883K(737280K), 0.0205490 secs] 4282207K->3632214K(9355264K)After GC:
> Statistics for BinaryTreeDictionary:
> ------------------------------------
> Total Free Space: 632933226
> Max   Chunk Size: 138752484
> Number of Blocks: 479784
> Av.  Block  Size: 1319
> Tree      Height: 34
> After GC:
> Statistics for BinaryTreeDictionary:
> ------------------------------------
> Total Free Space: 1829376
> Max   Chunk Size: 1829376
> Number of Blocks: 1
> Av.  Block  Size: 1829376
> Tree      Height: 1
> , 0.0239560 secs]
>
> On Sat, Feb 4, 2012 at 6:25 AM, Jonathan Ellis <jbellis@gmail.com> wrote:
>> We put a bunch of effort into reducing GC pauses in 1.0, which worked
>> great on our synthetic benchmarks but I don't have much data on how
>> well that's working in practice, on real-world workloads.
>>
>> If you're running a Cassandra app in production or testing, I'd
>> appreciate it if you could send me [either personally or via the list]
>> the results of enabling GC logging on one of your nodes by
>> uncommenting these lines in cassandra-env.sh:
>>
>> # JVM_OPTS="$JVM_OPTS -XX:+PrintGCDetails"
>> # JVM_OPTS="$JVM_OPTS -XX:+PrintGCDateStamps"
>> # JVM_OPTS="$JVM_OPTS -XX:+PrintHeapAtGC"
>> # JVM_OPTS="$JVM_OPTS -XX:+PrintTenuringDistribution"
>> # JVM_OPTS="$JVM_OPTS -XX:+PrintGCApplicationStoppedTime"
>> # JVM_OPTS="$JVM_OPTS -XX:+PrintPromotionFailure"
>> # JVM_OPTS="$JVM_OPTS -XX:PrintFLSStatistics=1"
>> # JVM_OPTS="$JVM_OPTS -Xloggc:/var/log/cassandra/gc-`date +%s`.log"
>>
>> (If you're running on Windows, you'll need to add these options
>> manually to cassandra.bat, and hardcode the log filename.)
>>
>> Besides the log file itself it would be useful to know JVM version,
>> how many cores your machine has, any GC options you have changed from
>> the default, and a high-level description of your workload (write
>> heavy? read heavy? slice reads, or query columns by name?  row cache
>> enabled, and if so, serializingcache with jna, or on-heap cache?)
>>
>> Thanks!
>>
>> P.S. It would be simplest if you can provide results for 1.0.7, which
>> IMO you would be well-served by upgrading to anyway, but all results
>> for 1.0.2+ are useful if you specify the version you are on.
>>
>> --
>> Jonathan Ellis
>> Project Chair, Apache Cassandra
>> co-founder of DataStax, the source for professional Cassandra support
>> http://www.datastax.com



-- 
Jonathan Ellis
Project Chair, Apache Cassandra
co-founder of DataStax, the source for professional Cassandra support
http://www.datastax.com

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