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From Mohit Anchlia <mohitanch...@gmail.com>
Subject Re: 答复: Frequent Full GC that take > 30s
Date Tue, 24 Sep 2013 04:18:32 GMT
Your ParNew size is way too small. Generally 4GB ParNew (-Xmn) works out
best for 16GB heap

On Mon, Sep 23, 2013 at 9:05 PM, 谢良 <xieliang@xiaomi.com> wrote:

> it looks to me that "MaxTenuringThreshold" is too small, do you have any
> chance to try with a bigger one, like 4 or 8 or sth else?
>
> ________________________________________
> 发件人: André Cruz [andre.cruz@co.sapo.pt]
> 发送时间: 2013年9月23日 22:51
> 收件人: user@cassandra.apache.org
> 主题: Frequent Full GC that take > 30s
>
> Hello.
>
> I'm having problems with frequent Full GCs that take a long time, and
> cause a burst of timeouts for the client application. But first, here is my
> configuration:
>
> Cassandra: 1.1.5
> Key Cache        : size 209715168 (bytes), capacity 209715168 (bytes),
> 1331992571 hits, 1831790912 requests, 0.854 recent hit rate, 14400 save
> period in seconds
> Row Cache        : size 104588313 (bytes), capacity 104857600 (bytes),
> 585590776 hits, 646992444 requests, 0.880 recent hit rate, 0 save period in
> seconds
> flush_largest_memtables_at: 0.8
> memtable_total_space_in_mb: 2048
>
> JVM:
> java version "1.6.0_35"
> Java(TM) SE Runtime Environment (build 1.6.0_35-b10)
> Java HotSpot(TM) 64-Bit Server VM (build 20.10-b01, mixed mode)
>
> JVM Options:
> -XX:+UseParNewGC
> -XX:+UseConcMarkSweepGC
> -XX:+CMSParallelRemarkEnabled
> -XX:SurvivorRatio=8
> -XX:MaxTenuringThreshold=1
> -XX:CMSInitiatingOccupancyFraction=75
> -XX:+UseCMSInitiatingOccupancyOnly
> -XX:ParallelCMSThreads=4
> -Xms16G
> -Xmx16G
> -Xmn800M
> -Xss196k
>
> 6 nodes with 32GB RAM, Intel(R) Xeon(R) CPU E5-2609, 300GB data per node.
>
>
> Current status:
> I had to raise the heap to 16GB due to constant very high heap usage. I've
> since lowered the bf ratio, but still haven't got to lowering the heap size
> because I'm still not sure a 8GB heap can handle the load per node.
>
> Things I plan to do:
> - upgrade to Cassandra 1.2. Supposedly it makes better use of the heap.
> - add more nodes. Still waiting for the hardware.
> - test again with lower heap sizes.
> - test JVM 7 (G1?). I've read somewhere that JVM 6 is recommended for
> Cassandra but Cassandra 2.0 requires JVM 7 so...
>
> Besides these, I would also like to double-check my current GC parameters.
> I'm thinking of increasing the NewSize to 1200M, so that less garbage ends
> up in the old generation. But here are the GC logs, maybe someone has a
> better idea?
>
> 2013-09-20T07:32:59.090+0100: 141675.121: [GC 141675.121: [ParNew (2:
> promotion failure size = 9564)  (promotion failed)
> Desired survivor size 41943040 bytes, new threshold 1 (max 1)
> - age   1:     569496 bytes,     569496 total
> : 85346K->67732K(737280K), 0.1206690 secs]
> 14838953K->14882152K(16695296K), 0.1210110 secs] [Times: user=0.58
> sys=0.01, real=0.12 secs]
> Heap after GC invocations=190322 (full 281):
>  par new generation   total 737280K, used 67732K [0x00000003fae00000,
> 0x000000042ce00000, 0x000000042ce00000)
>   eden space 655360K,   3% used [0x00000003fae00000, 0x00000003fc212690,
> 0x0000000422e00000)
>   from space 81920K,  57% used [0x0000000427e00000, 0x000000042ac12988,
> 0x000000042ce00000)
>   to   space 81920K,  79% used [0x0000000422e00000, 0x0000000426d46538,
> 0x0000000427e00000)
>  concurrent mark-sweep generation total 15958016K, used 14814420K
> [0x000000042ce00000, 0x00000007fae00000, 0x00000007fae00000)
>  concurrent-mark-sweep perm gen total 44188K, used 26411K
> [0x00000007fae00000, 0x00000007fd927000, 0x0000000800000000)
> }
> GC locker: Trying a full collection because scavenge failed
> {Heap before GC invocations=190322 (full 281):
>  par new generation   total 737280K, used 67732K [0x00000003fae00000,
> 0x000000042ce00000, 0x000000042ce00000)
>   eden space 655360K,   3% used [0x00000003fae00000, 0x00000003fc212690,
> 0x0000000422e00000)
>   from space 81920K,  57% used [0x0000000427e00000, 0x000000042ac12988,
> 0x000000042ce00000)
>   to   space 81920K,  79% used [0x0000000422e00000, 0x0000000426d46538,
> 0x0000000427e00000)
>  concurrent mark-sweep generation total 15958016K, used 14814420K
> [0x000000042ce00000, 0x00000007fae00000, 0x00000007fae00000)
>  concurrent-mark-sweep perm gen total 44188K, used 26411K
> [0x00000007fae00000, 0x00000007fd927000, 0x0000000800000000)
> 2013-09-20T07:32:59.212+0100: 141675.242: [Full GC 141675.242:
> [CMS2013-09-20T07:33:06.691+0100: 141682.721: [CMS-concurrent-sweep:
> 19.719/29.300 secs] [Times: user=146.19 sys=3.74, real=29.31 secs]
>  (concurrent mode failure): 14814420K->7653329K(15958016K), 35.8052520
> secs] 14882152K->7653329K(16695296K), [CMS Perm : 26411K->26355K(44188K)],
> 35.8055760 secs] [Times: user=35.74 sys=0.04, real=35.80 secs]
> Heap after GC invocations=190323 (full 282):
>  par new generation   total 737280K, used 0K [0x00000003fae00000,
> 0x000000042ce00000, 0x000000042ce00000)
>   eden space 655360K,   0% used [0x00000003fae00000, 0x00000003fae00000,
> 0x0000000422e00000)
>   from space 81920K,   0% used [0x0000000427e00000, 0x0000000427e00000,
> 0x000000042ce00000)
>   to   space 81920K,   0% used [0x0000000422e00000, 0x0000000422e00000,
> 0x0000000427e00000)
>  concurrent mark-sweep generation total 15958016K, used 7653329K
> [0x000000042ce00000, 0x00000007fae00000, 0x00000007fae00000)
>  concurrent-mark-sweep perm gen total 44188K, used 26355K
> [0x00000007fae00000, 0x00000007fd927000, 0x0000000800000000)
> }
> Total time for which application threads were stopped: 35.9305810 seconds
> Total time for which application threads were stopped: 0.0030240 seconds
>
>
> ...
>
>
> 2013-09-20T09:58:41.765+0100: 150417.795: [GC 150417.796: [ParNew
> Desired survivor size 41943040 bytes, new threshold 1 (max 1)
> - age   1:   83887848 bytes,   83887848 total
> : 674422K->81920K(737280K), 0.0680000 secs]
> 15824090K->15233726K(16695296K), 0.0685120 secs] [Times: user=0.54
> sys=0.00, real=0.07 secs]
> Heap after GC invocations=214529 (full 323):
>  par new generation   total 737280K, used 81920K [0x00000003fae00000,
> 0x000000042ce00000, 0x000000042ce00000)
>   eden space 655360K,   0% used [0x00000003fae00000, 0x00000003fae00000,
> 0x0000000422e00000)
>   from space 81920K, 100% used [0x0000000427e00000, 0x000000042ce00000,
> 0x000000042ce00000)
>   to   space 81920K,   0% used [0x0000000422e00000, 0x0000000422e00000,
> 0x0000000427e00000)
>  concurrent mark-sweep generation total 15958016K, used 15151806K
> [0x000000042ce00000, 0x00000007fae00000, 0x00000007fae00000)
>  concurrent-mark-sweep perm gen total 44188K, used 26424K
> [0x00000007fae00000, 0x00000007fd927000, 0x0000000800000000)
> }
> Total time for which application threads were stopped: 0.0721100 seconds
> {Heap before GC invocations=214529 (full 323):
>  par new generation   total 737280K, used 82214K [0x00000003fae00000,
> 0x000000042ce00000, 0x000000042ce00000)
>   eden space 655360K,   0% used [0x00000003fae00000, 0x00000003fae49998,
> 0x0000000422e00000)
>   from space 81920K, 100% used [0x0000000427e00000, 0x000000042ce00000,
> 0x000000042ce00000)
>   to   space 81920K,   0% used [0x0000000422e00000, 0x0000000422e00000,
> 0x0000000427e00000)
>  concurrent mark-sweep generation total 15958016K, used 15151806K
> [0x000000042ce00000, 0x00000007fae00000, 0x00000007fae00000)
>  concurrent-mark-sweep perm gen total 44188K, used 26424K
> [0x00000007fae00000, 0x00000007fd927000, 0x0000000800000000)
> 2013-09-20T09:58:41.837+0100: 150417.868: [GC 150417.868: [ParNew (0:
> promotion failure size = 1677)  (1: promotion failure size = 2584)  (2:
> promotion failure size = 2584)  (3: promotion failure size = 1723)  (4:
> promotion failure size = 1723)  (7: promotion failure size
>  = 4766)  (promotion failed)
> Desired survivor size 41943040 bytes, new threshold 1 (max 1)
> - age   1:      10688 bytes,      10688 total
> : 82214K->62920K(737280K), 0.4677070 secs]
> 15234020K->15298061K(16695296K), 0.4681720 secs] [Times: user=1.15
> sys=0.01, real=0.46 secs]
> Heap after GC invocations=214530 (full 323):
>  par new generation   total 737280K, used 62920K [0x00000003fae00000,
> 0x000000042ce00000, 0x000000042ce00000)
>   eden space 655360K,   0% used [0x00000003fae00000, 0x00000003fae49998,
> 0x0000000422e00000)
>   from space 81920K,  76% used [0x0000000422e00000, 0x0000000426b28940,
> 0x0000000427e00000)
>   to   space 81920K, 100% used [0x0000000427e00000, 0x000000042ce00000,
> 0x000000042ce00000)
>  concurrent mark-sweep generation total 15958016K, used 15235140K
> [0x000000042ce00000, 0x00000007fae00000, 0x00000007fae00000)
>  concurrent-mark-sweep perm gen total 44188K, used 26424K
> [0x00000007fae00000, 0x00000007fd927000, 0x0000000800000000)
> }
> GC locker: Trying a full collection because scavenge failed
> {Heap before GC invocations=214530 (full 323):
>  par new generation   total 737280K, used 62920K [0x00000003fae00000,
> 0x000000042ce00000, 0x000000042ce00000)
>   eden space 655360K,   0% used [0x00000003fae00000, 0x00000003fae49998,
> 0x0000000422e00000)
>   from space 81920K,  76% used [0x0000000422e00000, 0x0000000426b28940,
> 0x0000000427e00000)
>   to   space 81920K, 100% used [0x0000000427e00000, 0x000000042ce00000,
> 0x000000042ce00000)
>  concurrent mark-sweep generation total 15958016K, used 15235140K
> [0x000000042ce00000, 0x00000007fae00000, 0x00000007fae00000)
>  concurrent-mark-sweep perm gen total 44188K, used 26424K
> [0x00000007fae00000, 0x00000007fd927000, 0x0000000800000000)
> 2013-09-20T09:58:42.306+0100: 150418.336: [Full GC 150418.336:
> [CMS2013-09-20T09:58:46.720+0100: 150422.751: [CMS-concurrent-preclean:
> 7.057/10.443 secs] [Times: user=45.24 sys=0.32, real=10.44 secs]
>  (concurrent mode failure): 15235140K->5325067K(15958016K), 26.3214360
> secs] 15298061K->5325067K(16695296K), [CMS Perm : 26424K->26343K(44188K)],
> 26.3218650 secs] [Times: user=26.29 sys=0.02, real=26.33 secs]
> Heap after GC invocations=214531 (full 324):
>  par new generation   total 737280K, used 0K [0x00000003fae00000,
> 0x000000042ce00000, 0x000000042ce00000)
>   eden space 655360K,   0% used [0x00000003fae00000, 0x00000003fae00000,
> 0x0000000422e00000)
>   from space 81920K,   0% used [0x0000000422e00000, 0x0000000422e00000,
> 0x0000000427e00000)
>   to   space 81920K,   0% used [0x0000000427e00000, 0x0000000427e00000,
> 0x000000042ce00000)
>  concurrent mark-sweep generation total 15958016K, used 5325067K
> [0x000000042ce00000, 0x00000007fae00000, 0x00000007fae00000)
>  concurrent-mark-sweep perm gen total 44188K, used 26343K
> [0x00000007fae00000, 0x00000007fd927000, 0x0000000800000000)
> }
> Total time for which application threads were stopped: 26.7940000 seconds
> Total time for which application threads were stopped: 0.0408350 seconds
> Total time for which application threads were stopped: 0.0264510 seconds
>
>
>
> Thanks for the help,
> André Cruz
>

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