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The "Hbase/Troubleshooting" page has been changed by JeanDanielCryans. http://wiki.apache.org/hadoop/Hbase/Troubleshooting?action=diff&rev1=39&rev2=40 -------------------------------------------------- <<Anchor(9)>> == 9. Problem: ZooKeeper SessionExpired events == + * Master or Region Servers shutting down with messages like those in the logs: - * Master or RegionServers reinitialize their ZooKeeper wrappers after receiving SessionExpired events. - * Master or RegionServer ephemeral nodes disappear while the node is still otherwise functional. - * Messages those in the logs: {{{ WARN org.apache.zookeeper.ClientCnxn: Exception closing session 0x278bd16a96000f to sun.nio.ch.selectionkeyi...@355811ec @@ -186, +184 @@ === Causes === * The JVM is doing a long running garbage collecting which is pausing every threads (aka "stop the world"). * Since the region server's local zookeeper client cannot send heartbeats, the session times out. + * By design, we shut down any node that isn't able to contact the Zookeeper ensemble after getting a timeout so that it stops serving data that may already be assigned elsewhere. === Resolution === * Make sure you give plenty of RAM (in hbase-env.sh), the default of 1GB won't be able to sustain long running imports. * Make sure you don't swap, the JVM never behaves well under swapping.
