Robert Joseph Evans created ZOOKEEPER-2678:
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Summary: Large databases take a long time to regain a quorum
Key: ZOOKEEPER-2678
URL: https://issues.apache.org/jira/browse/ZOOKEEPER-2678
Project: ZooKeeper
Issue Type: Bug
Components: server
Affects Versions: 3.5.2, 3.4.9
Reporter: Robert Joseph Evans
Assignee: Robert Joseph Evans
I know this is long but please here me out.
I recently inherited a massive zookeeper ensemble. The snapshot is 3.4 GB on
disk. Because of its massive size we have been running into a number of
issues. There are lots of problems that we hope to fix with tuning GC etc, but
the big one right now that is blocking us making a lot of progress on the rest
of them is that when we lose a quorum because the leader left, for what ever
reason, it can take well over 5 mins for a new quorum to be established. So we
cannot tune the leader without risking downtime.
We traced down where the time was being spent and found that each server was
clearing the database so it would be read back in again before leader election
even started. Then as part of the sync phase each server will write out a
snapshot to checkpoint the progress it made as part of the sync.
I will be putting up a patch shortly with some proposed changes in it.
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