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https://issues.apache.org/jira/browse/HADOOP-6945?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13222446#comment-13222446
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Scott Carey commented on HADOOP-6945:
-------------------------------------
Both CDH3 and 1.0 break if using Avro 1.6.2. Avro 1.6.3 (currently a release
candidate) avoids using the Jackson bits that cause the issue when a Jackson
library between 1.3.x and 1.5.x is on the classpath (as with CDH3).
In our cluster we removed Jackson from all task tracker nodes (yet again, it
was OK for a while). One day Hadoop won't put a bunch of unnecessary crap on
M/R app classpaths and clearly distinguish libraries that are needed in this
context from things that are needed only for the framework. Jackson is one of
several libraries with similar issues.
> Inclusion of Old Jackson-JSON Breaks tasks using Avro (or any task depending
> on Jackson JSON)
> ---------------------------------------------------------------------------------------------
>
> Key: HADOOP-6945
> URL: https://issues.apache.org/jira/browse/HADOOP-6945
> Project: Hadoop Common
> Issue Type: Bug
> Affects Versions: 0.21.0
> Reporter: Greg Wittel
>
> HADOOP-6184 added the ability to serialize the Configuration to JSON.
> However its inclusion of jackson-1.0.1 means that any map-reduce task that
> depends (directly or indirectly) on Jackson, can only use Jackson 1.0.1 APIs.
> The 100% fix is to give the task's classpath priority over the core/common
> classpath (MAPREDUCE-1700/MAPREDUCE-1938) so that a job can use newer
> revisions of the library.
> For a nearer term fix, is it possible to upgrade the included Jackson library
> to a recent version (1.5.x+)? The APIs are backwards compatible.
> alernatively, its possible to eliminate the use of Jackson for this minor
> feature as the Configuration object could be serialized to JSON without a 3rd
> party library.
> An ancilliary issue is that the jackson.version referenced in ivy.xml is
> never specified in the source tree (ivy/libraries.properties).
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