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Fixing Oozie LZO ClassNotFound Errors and ShareLib Issues

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When LZO compression is enabled in Hadoop, Oozie may fail to launch MapReduce jobs with a ClassNotFoundException for the LzoCodec. This article explains why it happens, how to fix the missing hadoop-lzo classes on the Oozie server, how to correctly deploy the Oozie sharelib and how to enable the legacy uber-jar feature for MapReduce actions in CDH-era clusters.

Note (2025): This article documents behaviour from the CDH 4.x/5.x Oozie + MapReduce stack. Oozie is legacy and many teams migrate to Apache Airflow, Dagster, Argo or cloud-native schedulers, but troubleshooting old clusters still requires understanding these patterns. The solutions here apply to Hadoop MR/LZO deployments still in maintenance or migration mode.

Symptom: Oozie fails after enabling LZO compression

When you add LZO codecs to core-site.xml, Oozie may suddenly fail to start any MapReduce job. Typical configuration looks like: 

<property>
  <name>io.compression.codecs</name>
  <value>
    org.apache.hadoop.io.compress.GzipCodec,
    org.apache.hadoop.io.compress.DefaultCodec,
    com.hadoop.compression.lzo.LzoCodec,
    com.hadoop.compression.lzo.LzopCodec,
    org.apache.hadoop.io.compress.BZip2Codec
  </value>
</property>

<property>
  <name>io.compression.codec.lzo.class</name>
  <value>com.hadoop.compression.lzo.LzoCodec</value>
</property>

After restarting services, Oozie reports: 

java.lang.ClassNotFoundException:
  Class com.hadoop.compression.lzo.LzoCodec not found

Root cause

Even though LZO is installed on Hadoop nodes, Oozie runs inside its own server JVM and classpath. If hadoop-lzo.jar is missing from /var/lib/oozie/ (or the directory your Oozie installation loads from), Oozie cannot load the LZO codec classes and refuses to start jobs.

Fix: Install the LZO JAR on the Oozie server

Copy (or symlink) the hadoop-lzo.jar into the Oozie library directory and restart Oozie:

cp /usr/lib/hadoop/lib/hadoop-lzo.jar /var/lib/oozie/
service oozie restart

Once Oozie can load com.hadoop.compression.lzo.LzoCodec, MapReduce jobs using LZO compression start normally.

The second common issue: missing or incorrect ShareLib

Even with the LZO JAR fixed, Oozie may still fail if the sharelib is missing or has wrong permissions. The sharelib provides the job launcher classpath for Oozie workflows.

Typical setup:

# Create Oozie home in HDFS
sudo -u hdfs hadoop fs -mkdir /user/oozie
sudo -u hdfs hadoop fs -chown oozie:oozie /user/oozie

# Extract the sharelib
mkdir /tmp/share
cd /tmp/share
tar xvfz /usr/lib/oozie/oozie-sharelib.tar.gz

# Upload it to HDFS
sudo -u oozie hadoop fs -put share /user/oozie/share

After uploading, restart Oozie or run: 

oozie admin -sharelibupdate

Without a valid sharelib, Oozie cannot assemble the runtime classpath for MapReduce actions and will fail even if the LZO JAR is present on the Oozie server.

Uber JAR support (CDH 4.1+)

Starting with CDH 4.1, Oozie introduced a lightweight uber-jar feature. An uber-jar doesn’t bundle all dependencies into one fat JAR; instead, it carries references to dependent libraries in an internal lib/ directory.

To enable it globally, set the following in oozie-site.xml: 

<property>
  <name>oozie.action.mapreduce.uber.jar.enable</name>
  <value>true</value>
</property>

Once enabled, workflow authors can tag a MapReduce action with: 

oozie.mapreduce.uber.jar = <path-to-jar>

This tells Oozie that the provided JAR should be treated as an uber-jar, and Oozie will expand and distribute its libraries accordingly when launching the job.

Summary

  • LZO in core-site.xml often breaks Oozie because Oozie’s server classpath cannot see hadoop-lzo.jar.
  • Fix by copying hadoop-lzo.jar into /var/lib/oozie/.
  • Ensure /user/oozie/share exists and contains a valid sharelib.
  • Enable uber-jar support if your workflows depend on it.

With these steps, Oozie resumes launching MapReduce jobs correctly even when LZO compression is enabled cluster-wide.

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