enixon commented on a change in pull request #1045: ZOOKEEPER-3400: Add documentation on local sessions URL: https://github.com/apache/zookeeper/pull/1045#discussion_r320918230
########## File path: zookeeper-docs/src/main/resources/markdown/zookeeperProgrammers.md ########## @@ -503,6 +503,85 @@ new list and failing to connect, the client moves back to the normal mode of ope an arbitrary server from the connectString and attempts to connect to it. If that fails, it will continue trying different random servers in round robin. (see above the algorithm used to initially choose a server) +**local session**.Added in 3.5.0, mainly implemented by [ZOOKEEPER-1147](https://issues.apache.org/jira/browse/ZOOKEEPER-1147). + +- Background:The create and close of session is costly in zookeeper, especially when these operations of sessions need a +quorum confirmation by leader, which we call this session type: global session. it will be a bottle neck for ZooKeeper ensemble +when it wants to handle thousands of client connections. +So after 3.5.0, we introduce a new type of session: local session which doesn't have a full functionality of a normal(global) session. +,this feature will be available by turning on *localSessionsEnabled*. + +when *localSessionsUpgradingEnabled* is disable: + +- Local sessions cannot create ephemeral nodes + +- Once a local session is lost, users cannot re-establish it using the session-id/password. The session and its watches are gone for good. Review comment: Note that losing the tcp connection does not necessarily imply that the session is lost. If the connection can be reestablished with the same zk server before the session timeout then the client can continue (it simply cannot move to another server). ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org With regards, Apache Git Services
