Summary
I am new to Spark and I encountered an issue with saving text files using Snappy compression. I kept receiving the error message below. I followed many instructions from the Internet, but none of them worked for me. Eventually, I found a workaround but I like someone to advise on the right solution.
java.lang.UnsatisfiedLinkError: org.apache.hadoop.util.NativeCodeLoader.buildSupportsSnappy()Z
Tech stack
- Ubuntu 20.04.1 64-bit
- Hadoop 3.3.0
- Spark 3.0.0
- OpenJDK 1.8.0_272
I only use the spark-shell to test my code and I start it using:
spark-shell --master yarn \
--num-executors 1 \
--executor-memory 512M
What I tried to resolve the issue
Added the following environment variables inside the .bashrc
export JAVA_HOME=/usr/lib/jvm/java-8-openjdk-amd64
export HADOOP_HOME=/opt/hadoop
export PATH=$PATH:$HADOOP_HOME/bin:$HADOOP_HOME/sbin
export SPARK_HOME=/opt/spark
export PATH=$PATH:$SPARK_HOME/bin
export HADOOP_CONF_DIR=$HADOOP_HOME/etc/hadoop
Added the following environment variables inside the spark-env.sh
export JAVA_LIBRARY_PATH=$JAVA_LIBRARY_PATH:/opt/hadoop/lib/native
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/opt/hadoop/lib/native
export SPARK_YARN_USER_ENV="JAVA_LIBRARY_PATH=$JAVA_LIBRARY_PATH,LD_LIBRARY_PATH=$LD_LIBRARY_PATH"
Checked Snappy library is present
hadoop checknative
...
Native library checking:
hadoop: true /opt/hadoop/lib/native/libhadoop.so.1.0.0
zlib: true /lib/x86_64-linux-gnu/libz.so.1
zstd : true /lib/x86_64-linux-gnu/libzstd.so.1
snappy: true /lib/x86_64-linux-gnu/libsnappy.so.1
lz4: true revision:10301
bzip2: true /lib/x86_64-linux-gnu/libbz2.so.1
...
Workaround
I also tried to run the spark-shell without Yarn and I could save my RDD as a text file compressed by Snappy successfully. Hence, the issue seemed to be Yarn related. I added the following properties inside the spark-defaults.conf that eventually helped to get rid of the issue when Yarn was used. But I am not sure why this is actually needed and if this is the right approach to configure Spark on Yarn to use hadoop native libraries.
spark.driver.extraLibraryPath /opt/hadoop/lib/native
spark.executor.extraLibraryPath /opt/hadoop/lib/native