Github user mikhaildubkov commented on the pull request:
https://github.com/apache/spark/pull/12678#issuecomment-215239721
@tgravescs,
I have tried to use --jars, --files and so on, but the main reason why we
have to use "spark.executor.extraClassPath" is that we need add jar to
**CoarseGrainedExecutorBackend** classpath.
That is due to usage of **custom Spark serializer** in our project and
Spark instantiates serializer before loading any --jars/--files etc.
Here is the stack trace, which we have without
"spark.executor.extraClassPath" usage:
`Exception in thread "main" java.lang.reflect.UndeclaredThrowableException
at
org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1672)
at
org.apache.spark.deploy.SparkHadoopUtil.runAsSparkUser(SparkHadoopUtil.scala:68)
at
org.apache.spark.executor.CoarseGrainedExecutorBackend$.run(CoarseGrainedExecutorBackend.scala:151)
at
org.apache.spark.executor.CoarseGrainedExecutorBackend$.main(CoarseGrainedExecutorBackend.scala:253)
at
org.apache.spark.executor.CoarseGrainedExecutorBackend.main(CoarseGrainedExecutorBackend.scala)
Caused by: java.lang.ClassNotFoundException:
com.exeample.CustomSparkSerializer
at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:348)
at org.apache.spark.util.Utils$.classForName(Utils.scala:174)
at org.apache.spark.SparkEnv$.instantiateClass$1(SparkEnv.scala:286)
at
org.apache.spark.SparkEnv$.instantiateClassFromConf$1(SparkEnv.scala:307)
at org.apache.spark.SparkEnv$.create(SparkEnv.scala:310)
at org.apache.spark.SparkEnv$.createExecutorEnv(SparkEnv.scala:217)
at
org.apache.spark.executor.CoarseGrainedExecutorBackend$$anonfun$run$1.apply$mcV$sp(CoarseGrainedExecutorBackend.scala:186)
at
org.apache.spark.deploy.SparkHadoopUtil$$anon$1.run(SparkHadoopUtil.scala:69)
at
org.apache.spark.deploy.SparkHadoopUtil$$anon$1.run(SparkHadoopUtil.scala:68)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:422)
at
org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1657)
... 4 more`
As you can find, the serializer instantiates during Spark executor evn
creation time. There are no other possible options, which I found, to put jar
to the right place. Only "spark.executor.extraClassPath" helps.
I'll try one more time options that you mentioned, but I believe that I
already tried all of them.
The root cause, why it not works for me is that too late, the serializer
class instantiates before.
What do think about it?
Thank you!
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