Yip Ng created ZOOKEEPER-2052:
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Summary: Unable to delete a node when the node has no children
Key: ZOOKEEPER-2052
URL: https://issues.apache.org/jira/browse/ZOOKEEPER-2052
Project: ZooKeeper
Issue Type: Bug
Components: server
Affects Versions: 3.4.6
Environment: Red Hat Enterprise Linux 6.1 x86_64, standalone or 3 node
ensemble (v3.4.6), 2 Java clients (v3.4.6)
Reporter: Yip Ng
We stumbled upon a ZooKeeper bug where a node with no children cannot be
removed on our 3 node ZooKeeper ensemble or standalone ZooKeeper on Red Hat
Enterprise Linux x86_64 environment. Here is an example scenario/setup:
o Standalone ZooKeeper or 3 node ensemble (v3.4.6)
o 2 Java clients (v3.4.6)
- Client A creates a persistent node (e.g.: /metadata/resources)
- Client B creates ephemeral nodes under this persistent node
o Client A attempts to remove the /metadata/resources node via multi op
delete but fails since there are children
o Client B's session expired, all the ephemeral nodes are removed
o Client A attempts to recursively remove /metadata/resources node via
multi op, this is expected to succeed but got the following exception:
org.apache.zookeeper.KeeperException$NotEmptyException:
KeeperErrorCode = Directory not empty
(Note that Client B is the only client that creates these ephemeral nodes)
o After this, we use zkCli.sh to inspect the problematic node but the zkCli.sh
shows the /metadata/resources node indeed have no children but it will not
allow /metadata/resources node to get deleted. (shown below)
[zk: localhost:2181(CONNECTED) 0] ls /
[zookeeper, metadata]
[zk: localhost:2181(CONNECTED) 1] ls /metadata
[resources]
[zk: localhost:2181(CONNECTED) 2] get /metadata/resources
null
cZxid = 0x3
ctime = Wed Oct 01 22:04:11 PDT 2014
mZxid = 0x3
mtime = Wed Oct 01 22:04:11 PDT 2014
pZxid = 0x9
cversion = 2
dataVersion = 0
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 0
numChildren = 0
[zk: localhost:2181(CONNECTED) 3] delete /metadata/resources
Node not empty: /metadata/resources
[zk: localhost:2181(CONNECTED) 4] get /metadata/resources
null
cZxid = 0x3
ctime = Wed Oct 01 22:04:11 PDT 2014
mZxid = 0x3
mtime = Wed Oct 01 22:04:11 PDT 2014
pZxid = 0x9
cversion = 2
dataVersion = 0
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 0
numChildren = 0
o The only ways to remove this node is to either:
a) Restart the ZooKeeper server
b) set data to /metadata/resources then followed by a subsequent delete.
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