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https://issues.apache.org/jira/browse/HADOOP-10641?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14029899#comment-14029899
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Andrey Stepachev commented on HADOOP-10641:
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[~zero45], good work.
just a couple of picky notes :)
org/apache/hadoop/coordination/zk/ZkCoordinationEngine.java:117
Not configured localNodeId can lead to uncontrolled creation of new zk
sessions.
Should code check that before creating ZooKeeper object?
'catch' should close zookeeper, if it was opened.
org/apache/hadoop/coordination/zk/ZkCoordinationEngine.java:132
split doesn’t take into account chrooted zk configurations.
it is much better to use org.apache.zookeeper.client.ConnectStringParser
org/apache/hadoop/coordination/zk/ZkCoordinationEngine.java:301
currentGSN is long, but treated as integer. easy to create overflow.
More serious problem, that zk sequential nodes are _integer_.
Code should guard sequence overflows over zero and handle that using
more then one parent znodes or zero crossing detection or other techniques
preventing integer seqence id overflow.
> Introduce Coordination Engine
> -----------------------------
>
> Key: HADOOP-10641
> URL: https://issues.apache.org/jira/browse/HADOOP-10641
> Project: Hadoop Common
> Issue Type: New Feature
> Affects Versions: 3.0.0
> Reporter: Konstantin Shvachko
> Assignee: Plamen Jeliazkov
> Attachments: HADOOP-10641.patch, HADOOP-10641.patch,
> HADOOP-10641.patch
>
>
> Coordination Engine (CE) is a system, which allows to agree on a sequence of
> events in a distributed system. In order to be reliable CE should be
> distributed by itself.
> Coordination Engine can be based on different algorithms (paxos, raft, 2PC,
> zab) and have different implementations, depending on use cases, reliability,
> availability, and performance requirements.
> CE should have a common API, so that it could serve as a pluggable component
> in different projects. The immediate beneficiaries are HDFS (HDFS-6469) and
> HBase (HBASE-10909).
> First implementation is proposed to be based on ZooKeeper.
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