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The "ZooKeeper/FAQ" page has been changed by mahadevkonar. http://wiki.apache.org/hadoop/ZooKeeper/FAQ?action=diff&rev1=12&rev2=13 -------------------------------------------------- CONNECTION_LOSS means the link between the client and server was broken. It doesn't necessarily mean that the request failed. If you are doing a create request and the link was broken after the request reached the server and before the response was returned, the create request will succeed. If the link was broken before the packet went onto the wire, the create request failed. Unfortunately, there is no way for the client library to know, so it returns CONNECTION_LOSS. The programmer must figure out if the request succeeded or needs to be retried. Usually this is done in an application specific way. Examples of success detection include checking for the presence of a file to be created or checking the value of a znode to be modified. - When a client (session) becomes partitioned from the ZK serving cluster it will begin searching the list of servers that were specified during session creation. Eventually, when connectivity between the client and at least one of the servers is re-established, the session will either again transition to the "connected" state (if reconnected within the session timeout value) or it will transition to the "expired" state (if reconnected after the session timeout). It is not advisable to create a new session object (a new ZooKeeper.class or zookeeper handle in the c binding) for disconnection. The ZK client library will handle reconnect for you. In particular we have heuristics built into the client library to handle things like "herd effect", etc... Only create a new session when you are notified of session expiration (mandatory). + When a client (session) becomes partitioned from the ZK serving cluster it will begin searching the list of servers that were specified during session creation. Eventually, when connectivity between the client and at least one of the servers is re-established, the session will either again transition to the "connected" state (if reconnected within the session timeout value) or it will transition to the "expired" state (if reconnected after the session timeout). The ZK client library will handle reconnect for you automatically. In particular we have heuristics built into the client library to handle things like "herd effect", etc... Only create a new session when you are notified of session expiration (mandatory). <<BR>> <<Anchor(3)>>
