Using Azure Databricks Runtime 9.1, I want to start a SparkListener and access dbutils features inside of the SparkListener.
This listener should log some information on the start of the Spark application. It should list out the file system (as a simple example) using dbutils.fs.ls.
The question How to properly access dbutils in Scala when using Databricks Connect is super close to what I'm looking to do but they are focused on dbconnect whereas I want dbutils on a SparkListener. It does point to the dbutils api library on MS Docs page where it seems to indicate that I need only specify the correct target and version of the dbutils-api package.
In the sample listener below...
- If I do not include the
import com.databricks.dbutils_v1.DBUtilsHolder.dbutilsthe jar fails to compile since I referencedbutilsin theonApplicationStartmethod. - When I do include the import, it successfully compiles.
- However, it fails to initialize the SparkListener.
- I receive a NullPointerException after it tries to execute the
dbutils.fs.lscommand.
Any thoughts and/or guidance would be greatly appreciated!
Sample Listener Using dbutils on Application Start
package my.custom.listener
import java.util.logging.Logger
import org.apache.spark.scheduler.{SparkListener, SparkListenerApplicationStart}
import org.slf4j.{Logger, LoggerFactory}
// Crucial Import
import com.databricks.dbutils_v1.DBUtilsHolder.dbutils
class LibraryListener extends SparkListener {
private var isDatabricks = false
val log = LoggerFactory.getLogger(classOf[LibraryListener])
override def onApplicationStart(applicationStart: SparkListenerApplicationStart): Unit = {
log.info("HELLO WORLD!")
log.info(s"App Name ${applicationStart.appName}")
log.info(s"User ${applicationStart.sparkUser}")
isDatabricks = !(sys.env.get("DATABRICKS_RUNTIME_VERSION").isEmpty)
if (isDatabricks){
log.info("WE ARE USING DATABRICKS!")
// Dummy example of using dbutils
log.info(dbutils.fs.ls("dbfs:/"))
}
}
}
Error Message From Spark Listener Initialization
org.apache.spark.SparkException: Exception when registering SparkListener
at org.apache.spark.SparkContext.setupAndStartListenerBus(SparkContext.scala:2829)
at org.apache.spark.SparkContext.<init>(SparkContext.scala:701)
at com.databricks.backend.daemon.driver.DatabricksILoop$.$anonfun$initializeSharedDriverContext$1(DatabricksILoop.scala:347)
at com.databricks.backend.daemon.driver.ClassLoaders$.withContextClassLoader(ClassLoaders.scala:29)
at com.databricks.backend.daemon.driver.DatabricksILoop$.initializeSharedDriverContext(DatabricksILoop.scala:347)
at com.databricks.backend.daemon.driver.DatabricksILoop$.getOrCreateSharedDriverContext(DatabricksILoop.scala:277)
at com.databricks.backend.daemon.driver.DriverCorral.driverContext(DriverCorral.scala:229)
at com.databricks.backend.daemon.driver.DriverCorral.<init>(DriverCorral.scala:102)
at com.databricks.backend.daemon.driver.DriverDaemon.<init>(DriverDaemon.scala:50)
at com.databricks.backend.daemon.driver.DriverDaemon$.create(DriverDaemon.scala:287)
at com.databricks.backend.daemon.driver.DriverDaemon$.wrappedMain(DriverDaemon.scala:362)
at com.databricks.DatabricksMain.$anonfun$main$1(DatabricksMain.scala:117)
at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:23)
at com.databricks.DatabricksMain.$anonfun$withStartupProfilingData$1(DatabricksMain.scala:425)
at com.databricks.logging.UsageLogging.$anonfun$recordOperation$1(UsageLogging.scala:395)
at com.databricks.logging.UsageLogging.executeThunkAndCaptureResultTags$1(UsageLogging.scala:484)
at com.databricks.logging.UsageLogging.$anonfun$recordOperationWithResultTags$4(UsageLogging.scala:504)
at com.databricks.logging.UsageLogging.$anonfun$withAttributionContext$1(UsageLogging.scala:266)
at scala.util.DynamicVariable.withValue(DynamicVariable.scala:62)
at com.databricks.logging.UsageLogging.withAttributionContext(UsageLogging.scala:261)
at com.databricks.logging.UsageLogging.withAttributionContext$(UsageLogging.scala:258)
at com.databricks.DatabricksMain.withAttributionContext(DatabricksMain.scala:85)
at com.databricks.logging.UsageLogging.withAttributionTags(UsageLogging.scala:305)
at com.databricks.logging.UsageLogging.withAttributionTags$(UsageLogging.scala:297)
at com.databricks.DatabricksMain.withAttributionTags(DatabricksMain.scala:85)
at com.databricks.logging.UsageLogging.recordOperationWithResultTags(UsageLogging.scala:479)
at com.databricks.logging.UsageLogging.recordOperationWithResultTags$(UsageLogging.scala:404)
at com.databricks.DatabricksMain.recordOperationWithResultTags(DatabricksMain.scala:85)
at com.databricks.logging.UsageLogging.recordOperation(UsageLogging.scala:395)
at com.databricks.logging.UsageLogging.recordOperation$(UsageLogging.scala:367)
at com.databricks.DatabricksMain.recordOperation(DatabricksMain.scala:85)
at com.databricks.DatabricksMain.withStartupProfilingData(DatabricksMain.scala:425)
at com.databricks.DatabricksMain.main(DatabricksMain.scala:116)
at com.databricks.backend.daemon.driver.DriverDaemon.main(DriverDaemon.scala)
Caused by: java.lang.NullPointerException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at com.databricks.dbutils_v1.DBUtilsHolder$$anon$1.invoke(DBUtilsHolder.scala:17)
at com.sun.proxy.$Proxy35.fs(Unknown Source)
at my.custom.listener.LibraryListener.<init>(LibraryListener.scala:19)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at org.apache.spark.util.Utils$.$anonfun$loadExtensions$1(Utils.scala:3077)
at scala.collection.TraversableLike.$anonfun$flatMap$1(TraversableLike.scala:245)
at scala.collection.mutable.ResizableArray.foreach(ResizableArray.scala:62)
at scala.collection.mutable.ResizableArray.foreach$(ResizableArray.scala:55)
at scala.collection.mutable.ArrayBuffer.foreach(ArrayBuffer.scala:49)
at scala.collection.TraversableLike.flatMap(TraversableLike.scala:245)
at scala.collection.TraversableLike.flatMap$(TraversableLike.scala:242)
at scala.collection.AbstractTraversable.flatMap(Traversable.scala:108)
at org.apache.spark.util.Utils$.loadExtensions(Utils.scala:3066)
at org.apache.spark.SparkContext.$anonfun$setupAndStartListenerBus$1(SparkContext.scala:2810)
at org.apache.spark.SparkContext.$anonfun$setupAndStartListenerBus$1$adapted(SparkContext.scala:2809)
at scala.Option.foreach(Option.scala:407)
at org.apache.spark.SparkContext.setupAndStartListenerBus(SparkContext.scala:2809)
... 33 more
build.gradle
plugins {
id 'scala'
id 'java-library'
}
repositories {
mavenCentral()
}
dependencies {
// Use Scala 2.13 in our library project
implementation 'org.scala-lang:scala-library:2.12.15'
// Crucial Implementation
// https://mvnrepository.com/artifact/com.databricks/dbutils-api
implementation group: 'com.databricks', name: 'dbutils-api_2.12', version: '0.0.5'
implementation group: 'org.slf4j', name: 'slf4j-api', version: '1.7.32'
implementation group: 'org.apache.spark', name: 'spark-core_2.12', version: '3.0.0'
implementation group: 'org.apache.spark', name: 'spark-sql_2.12', version: '3.0.0'
implementation 'com.google.guava:guava:30.1.1-jre'
testImplementation 'junit:junit:4.13.2'
testImplementation 'org.scalatest:scalatest_2.12:3.2.9'
testImplementation 'org.scalatestplus:junit-4-13_2.12:3.2.2.0'
testImplementation group: 'org.slf4j', name: 'slf4j-simple', version: '1.7.32'
testRuntimeOnly 'org.scala-lang.modules:scala-xml_2.12:1.2.0'
api 'org.apache.commons:commons-math3:3.6.1'
}
Thank you for any insights!
