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From Viktor Jevdokimov <>
Subject RE: Cassandra mad GC
Date Wed, 15 Jan 2014 08:17:54 GMT
Simply don't use G1 GC, it will not be better on Cassandra than CMS, it could be worse.

Best regards / Pagarbiai

Viktor Jevdokimov
Senior Developer

Phone: +370 5 212 3063
Fax: +370 5 261 0453

J. Jasinskio 16C,
LT-03163 Vilnius,

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and any copies.-----Original Message-----
From: Dimetrio []
Sent: Tuesday, January 14, 2014 3:16 PM
Subject: Cassandra mad GC

Hi all.
I have many GC freezes on my cassandra cluster

Im using G1 GC and CMS gives similar freezes JVM_OPTS="$JVM_OPTS -XX:+UseG1GC"
JVM_OPTS="$JVM_OPTS -XX:SurvivorRatio=1"
JVM_OPTS="$JVM_OPTS -XX:MaxTenuringThreshold=15"
JVM_OPTS="$JVM_OPTS -XX:-UseAdaptiveSizePolicy"
JVM_OPTS="$JVM_OPTS -XX:G1HeapRegionSize=32m"

Heap 8GB
10 nodes aws c3.4xlarge
60Gb per node

Cassandra logs

GC logs

sometimes node freeze and told that one or two nodes are down cpu load > 1000% LA = 6-15

pending tasks: 4
          compaction type        keyspace           table       completed
total      unit  progress
               Compaction          Social   home_timeline      4097097092
4920701908     bytes    83.26%
               Compaction          Social   home_timeline      2713279974
6272012039     bytes    43.26%
Active compaction remaining time :   0h00m32s

200-300 requests per second on each node with many inserts and deletes (batch lower than 50)

How can i reduce GC freezes?


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