What is the use of --driver-class-path in the spark command? - apache-spark

As per spark docs,
To get started you will need to include the JDBC driver for you particular database on the spark classpath. For example, to connect to postgres from the Spark Shell you would run the following command:
bin/spark-shell --driver-class-path postgresql-9.4.1207.jar --jars postgresql-9.4.1207.jar
Job is working fine without --driver-class-path. Then, what is the use of --driver-class-path in the spark command?

--driver-class-path or spark.driver.extraClassPath can be used for to modify class path only for the Spark driver. This is useful for libraries which are not required by the executors (for example any code that is used only locally).
Compared to that, --jars or spark.jars will not only add jars to both driver and executor classpath, but also distribute archives over the cluster. If particular jar is used only by the driver this is unnecessary overhead.

Let's say we run the following command with Spark 3.3.0:
spark-submit --driver-class-path DCP.jar --jars JARS.jar MAIN.jar
What the scripts will actually execute is:
java
-cp DCP.jar:spark/conf:spark/jars/*
org.apache.spark.deploy.SparkSubmit
--conf spark.driver.extraClassPath=DCP.jar
--jars JARS.jar
MAIN.jar
(I've removed the irrelevant bits.)
The surprise (for me) is that only DCP.jar is on the classpath. Neither JARS.jar nor MAIN.jar are on the JVM classpath. This means any JDBC driver registration from those jars will not be activated. You need to put the JDBC jar on --driver-class-path.
But you also want the workers to be able to do JDBC. So you need to put the JDBC jar on --jars too. Both are required, like the documentation says.

Related

Remove JAR from Spark default classpath in EMR

I'm executing a spark-submit script in an EMR step that has my super JAR as the main class, like
spark-submit \
....
--class ${MY_CLASS} "${SUPER_JAR_S3_PATH}"
... etc
but Spark is by default loading the jar file:/usr/lib/spark/jars/guice-3.0.jar which contains com.google.inject.internal.InjectorImpl, a class that's also in the Guice-4.x jar which is in my super JAR. This results in a java.lang.IllegalAccessError when my service is booting up.
I've tried setting some Spark conf in the spark-submit to put my super jar in the classpath in hopes of it getting loaded first, before Spark loads guice-3.0.jar. It looks like:
--jars "${ASSEMBLY_JAR_S3_PATH}" \
--driver-class-path "/etc/hadoop/conf:/etc/hive/conf:/usr/lib/hadoop-lzo/lib/*:/usr/share/aws/aws-java-sdk/*:/usr/share/aws/emr/emrfs/conf:/usr/share/aws/emr/emrfs/lib/*:/usr/share/aws/emr/emrfs/auxlib/*:${SUPER_JAR_S3_PATH}" \
--conf spark.executor.extraClassPath="/etc/hadoop/conf:/etc/hive/conf:/usr/lib/hadoop-lzo/lib/*:/usr/share/aws/aws-java-sdk/*:/usr/share/aws/emr/emrfs/conf:/usr/share/aws/emr/emrfs/lib/*:/usr/share/aws/emr/emrfs/auxlib/*:${SUPER_JAR_S3_PATH}" \
but this results in the same error.
Is there a way to remove that guice-3.0.jar from the default spark classpath so my code can use the InjectorImpl that's packaged in the Guice-4.x JAR? I'm also running Spark in client mode so I can't use spark.driver.userClassPathFirst or spark.executor.userClassPathFirst
one way is point to lib where your guice old version of jar is there and then exclude it.
sample shell script for spark-submit :
export latestguicejar='your path to latest guice jar'
#!/bin/sh
# build all other dependent jars in OTHER_JARS
JARS=`find /usr/lib/spark/jars/ -name '*.jar'`
OTHER_JARS=""
for eachjarinlib in $JARS ; do
if [ "$eachjarinlib" != "guice-3.0.jar" ]; then
OTHER_JARS=$eachjarinlib,$OTHER_JARS
fi
done
echo ---final list of jars are : $OTHER_JARS
echo $CLASSPATH
spark-submit --verbose --class <yourclass>
... OTHER OPTIONS
--jars $OTHER_JARS,$latestguicejar,APPLICATIONJARTOBEADDEDSEPERATELY.JAR
also see holdens answer. check with your version of the spark what is available.
As per docs runtime-environment userClassPathFirst are present in the latest version of spark as of today.
spark.executor.userClassPathFirst
spark.driver.userClassPathFirst
for this to use you can make uber jar with all application level dependencies.

Submitting application on Spark Cluster using spark submit

I am new to Spark.
I want to run a Spark Structured Streaming application on cluster.
Master and workers has same configuration.
I have few queries for submitting app on cluster using spark-submit:
You may find them comical or strange.
How can I give path for 3rd party jars like lib/*? ( Application has 30+ jars)
Will Spark automatically distribute application and required jars to workers?
Does it require to host application on all the workers?
How can i know status of my application as I am working on console.
I am using following script for Spark-submit.
spark-submit
--class <class-name>
--master spark://master:7077
--deploy-mode cluster
--supervise
--conf spark.driver.extraClassPath <jar1, jar2..jarn>
--executor-memory 4G
--total-executor-cores 8
<running-jar-file>
But code is not running as per expectation.
Am i missing something?
To pass multiple jar file to Spark-submit you can set the following attributes in file SPARK_HOME_PATH/conf/spark-defaults.conf (create if not exists):
Don't forget to use * at the end of the paths
spark.driver.extraClassPath /fullpath/to/jar/folder/*
spark.executor.extraClassPath /fullpathto/jar/folder/*
Spark will set the attributes in the file spark-defaults.conf when you use the spark-submit command.
Copy your jar file on that directory and when you submit your Spark App on the cluster, the jar files in the specified paths will be loaded, too.
spark.driver.extraClassPath: Extra classpath entries to prepend
to the classpath of the driver. Note: In client mode, this config
must not be set through the SparkConf directly in your application,
because the driver JVM has already started at that point. Instead,
please set this through the --driver-class-path command line option or
in your default properties file.
--jars will transfer your jar files to worker nodes, and become available in both driver and executors' classpaths.
Please refer below link to see more details.
http://spark.apache.org/docs/latest/submitting-applications.html#advanced-dependency-management
You can make a fat jar containing all dependencies. Below link helps you understand that.
https://community.hortonworks.com/articles/43886/creating-fat-jars-for-spark-kafka-streaming-using.html

Spark-shell vs Spark-submit adding jar to classpath issue

I'm able to run CREATE TEMPORARY FUNCTION testFunc using jar 'myJar.jar' query in hiveContext via spark-shell --jars myJar.jar -i some_script.scala, but I'm not able to run such command via spark-submit --class com.my.DriverClass --jars myJar.jar target.jar.
Am I doing something wrong?
If you are using local file system, the Jar must be in the same location on all nodes.
So you have 2 options:
place jar on all nodes in the same directory, for example in /home/spark/my.jar and then use this directory in --jars option.
use distributed file system like HDFS

can't add alluxio.security.login.username to spark-submit

I have a spark driver program which I'm trying to set the alluxio user for.
I read this post: How to pass -D parameter or environment variable to Spark job? and although helpful, none of the methods in there seem to do the trick.
My environment:
- Spark-2.2
- Alluxio-1.4
- packaged jar passed to spark-submit
The spark-submit job is being run as root (under supervisor), and alluxio only recognizes this user.
Here's where I've tried adding "-Dalluxio.security.login.username=alluxio":
spark.driver.extraJavaOptions in spark-defaults.conf
on the command line for spark-submit (using --conf)
within the sparkservices conf file of my jar application
within a new file called "alluxio-site.properties" in my jar application
None of these work set the user for alluxio, though I'm easily able to set this property in a different (non-spark) client application that is also writing to alluxio.
Anyone able to make this setting apply in spark-submit jobs?
If spark-submit is in client mode, you should use --driver-java-options instead of --conf spark.driver.extraJavaOptions=... in order for the driver JVM to be started with the desired options. Therefore your command would look something like:
./bin/spark-submit ... --driver-java-options "-Dalluxio.security.login.username=alluxio" ...
This should start the driver with the desired Java options.
If the Spark executors also need the option, you can set that with:
--conf "spark.executor.extraJavaOptions=-Dalluxio.security.login.username=alluxio"

spark-submit in deploy mode client not reading all the jars

I'm trying to submit an application to my spark cluster (standalone mode) through the spark-submit command. I'm following the
official spark documentation, as well as relying on this other one. Now the problem is that I get strange behaviors. My setup is the following:
I have a directory where all the dependency jars for my application are located, that is /home/myuser/jars
The jar of my application is in the same directory (/home/myuser/jars), and is called dat-test.jar
The entry point class in dat-test.jar is at the package path my.package.path.Test
Spark master is at spark://master:7077
Now, I submit the application directly on the master node, thus using the client deploy mode, running the command
./spark-submit --class my.package.path.Test --master spark://master:7077 --executor-memory 5G --total-executor-cores 10 /home/myuser/jars/*
and I received an error as
java.lang.ClassNotFoundException: my.package.path.Test
If I activate the verbose mode, what I see is that the primaryResource selected as jar containing the entry point is the first jar by alphabetical order in /home/myuser/jars/ (that is not dat-test.jar), leading (I supppose) to the ClassNotFoundException. All the jars in the same directory are anyway loaded as arguments.
Of course if I run
./spark-submit --class my.package.path.Test --master spark://master:7077 --executor-memory 5G --total-executor-cores 10 /home/myuser/jars/dat-test.jar
it finds the Test class, but it doesn't find other classes contained in other jars. Finally, if I use the --jars flag and run
./spark-submit --class my.package.path.Test --master spark://master:7077 --executor-memory 5G --total-executor-cores 10 --jars /home/myuser/jars/* /home/myuser/jars/dat-test.jar
I obtain the same result as the first option. First jar in /home/myuser/jars/ is loaded as primaryResource, leading to ClassNotFoundException for my.package.path.Test. Same if I add --jars /home/myuser/jars/*.jar.
Important points are:
I do not want to have a single jar with all the dependencies for development reasons
The jars in /home/myuser/jars/ are many. I'd like to know if there's a way to include them all instead of using the comma separated syntax
If I try to run the same commands with --deploy-cluster on the master node, I don't get the error, but the computation fails for some other reasons (but this is another problem).
Which is then the correct way of running a spark-submit in client mode?
Thanks
There is no way to include all jars using the --jars option, you will have to create a small script to enumerate them. This part is a bit sub-optimal.

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