On 5/3/2017 7:32 AM, Satya Marivada wrote: > I see below exceptions in my logs sometimes. What could be causing it? > > org.apache.zookeeper.KeeperException$SessionExpiredException:
Based on my limited research, this would tend to indicate that the heartbeats ZK uses to detect when sessions have gone inactive are not occurring in a timely fashion. Common causes seem to be: JVM Garbage collections. These can cause the entire JVM to pause for an extended period of time, and this time may exceed the configured timeouts. Excess client connections to ZK. ZK limits the number of connections from each client address, with the idea of preventing denial of service attacks. If a client is misbehaving, it may make more connections than it should. You can try increasing the limit in the ZK config, but if this is the reason for the exception, then something's probably wrong, and you may be just hiding the real problem. Although we might have bugs causing the second situation, the first situation seems more likely. Thanks, Shawn
