Hadriel Kaplan created ZOOKEEPER-2648:
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Summary: Container node never gets deleted if it never had children
Key: ZOOKEEPER-2648
URL: https://issues.apache.org/jira/browse/ZOOKEEPER-2648
Project: ZooKeeper
Issue Type: Bug
Components: server
Affects Versions: 3.5.0
Reporter: Hadriel Kaplan
If a client creates a Container node, but does not also create a child within
that Container, the Container will never be deleted. This may seem like a bug
in the client for not subsequently creating a child, but we can't assume the
client remains connected, or that the client didn't just change its mind (due
to some recipe being canceled, for example).
The bug is in ContainerManager.getCandidates(), which only considers a node a
candidate if its Cversion > 0. The comments indicate this was done
intentionally, to avoid a race condition whereby the Container was created
right before a cleaning period, and would get cleaned up before the child could
be created - so to avoid that the check is performed to verify the Cversion > 0.
Instead, I propose that if the Cversion is 0 but the Ctime is more than a
checkIntervalMs old, then it be deleted. In other words, if the Container node
has been around for a whole cleaning round already and no child has been
created since, then go ahead and clean it up.
I can provide a patch if others agree with such a change.
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