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https://issues.apache.org/jira/browse/HADOOP-16579?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16934207#comment-16934207
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Mate Szalay-Beko commented on HADOOP-16579:
-------------------------------------------
There are some... I compared the dependencies which changed between 4.2.0 ([see
here|https://mvnrepository.com/artifact/org.apache.curator/apache-curator/4.2.0])
and 2.12.0 ([see
here|https://mvnrepository.com/artifact/org.apache.curator/apache-curator/2.12.0]):
||Lib||Curator 2.12.0||Curator 4.2.0||
|com.facebook.swift|0.12.0|0.23.1|
|com.fasterxml.jackson|n/a|2.9.8|
|com.google.guava|16.0.1|27.0.1-jre|
|com.sun.jersey|1.18.1|1.19.4|
|io.dropwizard (configuration and logging)|0.7.0|1.3.7|
|org.apache.commons|2.2|2.2|
|org.jboss.resteasy|2.3.0.GA|2.3.5.Final|
|org.slf4j|1.7.6|1.7.25|
We actually built Hadoop already with the new Curator and new ZooKeeper (I
think we even deployed and executed some smoke tests) without touching the rest
of the dependencies. But I think it would be important to review these changes
above in the table and decide for each Curator dependency if we want to include
it as it is or if we want to exclude and use Hadoop's version.
> Upgrade to Apache Curator 4.2.0 in Hadoop
> -----------------------------------------
>
> Key: HADOOP-16579
> URL: https://issues.apache.org/jira/browse/HADOOP-16579
> Project: Hadoop Common
> Issue Type: Improvement
> Reporter: Mate Szalay-Beko
> Priority: Major
>
> Currently in Hadoop we are using [ZooKeeper version
> 3.4.13|https://github.com/apache/hadoop/blob/7f9073132dcc9db157a6792635d2ed099f2ef0d2/hadoop-project/pom.xml#L90].
> ZooKeeper 3.5.5 is the latest stable Apache ZooKeeper release. It contains
> many new features (including SSL related improvements which can be very
> important for production use; see [the release
> notes|https://zookeeper.apache.org/doc/r3.5.5/releasenotes.html]).
> Apache Curator is a high level ZooKeeper client library, that makes it easier
> to use the low level ZooKeeper API. Currently [in Hadoop we are using Curator
> 2.13.0|https://github.com/apache/hadoop/blob/7f9073132dcc9db157a6792635d2ed099f2ef0d2/hadoop-project/pom.xml#L91]
> and [in Ozone we use Curator
> 2.12.0|https://github.com/apache/hadoop/blob/7f9073132dcc9db157a6792635d2ed099f2ef0d2/pom.ozone.xml#L146].
> Curator 2.x is supporting only the ZooKeeper 3.4.x releases, while Curator
> 3.x is compatible only with the new ZooKeeper 3.5.x releases. Fortunately,
> the latest Curator 4.x versions are compatible with both ZooKeeper 3.4.x and
> 3.5.x. (see [the relevant Curator
> page|https://curator.apache.org/zk-compatibility.html]). Many Apache projects
> have already migrated to Curator 4 (like HBase, Phoenix, Druid, etc.), other
> components are doing it right now (e.g. Hive).
> *The aims of this task are* to:
> - change Curator version in Hadoop to the latest stable 4.x version
> (currently 4.2.0)
> - also make sure we don't have multiple ZooKeeper versions in the classpath
> to avoid runtime problems (it is
> [recommended|https://curator.apache.org/zk-compatibility.html] to exclude the
> ZooKeeper which come with Curator, so that there will be only a single
> ZooKeeper version used runtime in Hadoop)
> In this ticket we still don't want to change the default ZooKeeper version in
> Hadoop, we only want to make it possible for the community to be able to
> build / use Hadoop with the new ZooKeeper (e.g. if they need to secure the
> ZooKeeper communication with SSL, what is only supported in the new ZooKeeper
> version). Upgrading to Curator 4.x should keep Hadoop to be compatible with
> both ZooKeeper 3.4 and 3.5.
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