环境
我有以下环境：
- 卡桑德拉 2.1.0
- 一个 DC 5 个节点，第二个 DC 4 个节点
- 每秒 2500 次写入
- 最少读取（通常没有，有时很少）
问题
一个节点运行时间长后，GC开始耗时越来越长，直到nodetool报告这个节点宕机。
我可视化 gc.log 并有以下屏幕截图：
JVM 设置
评论后，工作 Cassandra 的完整命令行是：
java -ea -javaagent:/usr/lib/cassandra/bin/../lib/jamm-0.2.6.jar
-XX:+UseThreadPriorities
-XX:ThreadPriorityPolicy=42
-Xms8192M
-Xmx8192M
-Xmn2048M
-XX:+HeapDumpOnOutOfMemoryError
-Xss192k
-XX:+UseParNewGC
-XX:+UseConcMarkSweepGC
-XX:+CMSParallelRemarkEnabled
-XX:SurvivorRatio=8
-XX:MaxTenuringThreshold=1
-XX:CMSInitiatingOccupancyFraction=75
-XX:+UseCMSInitiatingOccupancyOnly
-XX:+PrintGCDetails
-XX:+PrintGCTimeStamps
-XX:+PrintClassHistogram
-XX:+PrintTenuringDistribution
-XX:+PrintGCApplicationStoppedTime
-Xloggc:/var/log/cassandra/gc.log
-Djava.net.preferIPv4Stack=true
-Dcom.sun.management.jmxremote.port=8080
-Dcom.sun.management.jmxremote.ssl=false
-Dcom.sun.management.jmxremote.authenticate=false
-Dlogback.configurationFile=logback.xml
-Dcassandra.logdir=/usr/lib/cassandra/bin/../logs
-Dcassandra.storagedir=/usr/lib/cassandra/bin/../data
-Dcassandra-pidfile=/var/run/cassandra.pid
-cp /usr/lib/cassandra/bin/../conf:/usr/lib/cassandra/bin/../build/classes/main:/usr/lib/cassandra/bin/../build/classes/thrift:/usr/lib/cassandra/bin/../lib/airline-0.6.jar:/usr/lib/cassandra/bin/../lib/antlr-3.2.jar:/usr/lib/cassandra/bin/../lib/apache-cassandra-2.1.0.jar:/usr/lib/cassandra/bin/../lib/apache-cassandra-clientutil-2.1.0.jar:/usr/lib/cassandra/bin/../lib/apache-cassandra-thrift-2.1.0.jar:/usr/lib/cassandra/bin/../lib/commons-cli-1.1.jar:/usr/lib/cassandra/bin/../lib/commons-codec-1.2.jar:/usr/lib/cassandra/bin/../lib/commons-lang3-3.1.jar:/usr/lib/cassandra/bin/../lib/commons-math3-3.2.jar:/usr/lib/cassandra/bin/../lib/compress-lzf-0.8.4.jar:/usr/lib/cassandra/bin/../lib/concurrentlinkedhashmap-lru-1.4.jar:/usr/lib/cassandra/bin/../lib/disruptor-3.0.1.jar:/usr/lib/cassandra/bin/../lib/guava-16.0.jar:/usr/lib/cassandra/bin/../lib/high-scale-lib-1.0.6.jar:/usr/lib/cassandra/bin/../lib/jackson-core-asl-1.9.2.jar:/usr/lib/cassandra/bin/../lib/jackson-mapper-asl-1.9.2.jar:/usr/lib/cassandra/bin/../lib/jamm-0.2.6.jar:/usr/lib/cassandra/bin/../lib/javax.inject.jar:/usr/lib/cassandra/bin/../lib/jbcrypt-0.3m.jar:/usr/lib/cassandra/bin/../lib/jline-1.0.jar:/usr/lib/cassandra/bin/../lib/jna-4.0.0.jar:/usr/lib/cassandra/bin/../lib/jna.jar:/usr/lib/cassandra/bin/../lib/json-simple-1.1.jar:/usr/lib/cassandra/bin/../lib/libthrift-0.9.1.jar:/usr/lib/cassandra/bin/../lib/logback-classic-1.1.2.jar:/usr/lib/cassandra/bin/../lib/logback-core-1.1.2.jar:/usr/lib/cassandra/bin/../lib/lz4-1.2.0.jar:/usr/lib/cassandra/bin/../lib/metrics-core-2.2.0.jar:/usr/lib/cassandra/bin/../lib/netty-all-4.0.20.Final.jar:/usr/lib/cassandra/bin/../lib/reporter-config-2.1.0.jar:/usr/lib/cassandra/bin/../lib/slf4j-api-1.7.2.jar:/usr/lib/cassandra/bin/../lib/snakeyaml-1.11.jar:/usr/lib/cassandra/bin/../lib/snappy-java-1.0.5.2.jar:/usr/lib/cassandra/bin/../lib/stream-2.5.2.jar:/usr/lib/cassandra/bin/../lib/super-csv-2.1.0.jar:/usr/lib/cassandra/bin/../lib/thrift-server-0.3.5.jar org.apache.cassandra.service.CassandraDaemon
问题
我应该检查什么以找出问题所在？此外，我最近
com.google.common.util.concurrent.UncheckedExecutionException：java.lang.RuntimeException：org.apache.cassandra.exceptions.ReadTimeoutException：操作超时 - 仅收到 2 个响应