田毅群 created ZOOKEEPER-3169:
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Summary: Reduce session revalidation time after zxid roll over
Key: ZOOKEEPER-3169
URL: https://issues.apache.org/jira/browse/ZOOKEEPER-3169
Project: ZooKeeper
Issue Type: Improvement
Affects Versions: 3.5.0, 3.4.5
Reporter: 田毅群
Fix For: 3.4.5
1. Sometimes Zookeeper cluster will receive a lot of connections from clients,
sometimes connection number even exceeds 1W. When zxid rolls over, the clients
will reconnect and revalidate the session.
2. In Zookeeper design structure, when follower server receives the session
revalidation requests, it will send requests to leader server, which is
designed to be responsible for session revalidation.
3. In a short time, Leader will handle lots of requests. I use a tool to get
the statistics, some clients need to wait over 20s. It is too long for some
special clients, like ResourceManager.
4. I design a thought: when zxid rollover happens. Leader will record the
accurate time. When reelection finishs, all servers will get the rollover time.
When clients reconnect and revalidate session. All servers can judge it. So it
can reduce a lots of pressure of cluster, all clients can will wait for less
time.
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