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Posted to issues@beam.apache.org by "Mazlum Tosun (Jira)" <ji...@apache.org> on 2021/05/02 00:24:00 UTC

[jira] [Updated] (BEAM-12265) FlatMapElement Kotlin Beam non Serializable lambda

     [ https://issues.apache.org/jira/browse/BEAM-12265?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Mazlum Tosun updated BEAM-12265:
--------------------------------
    Description: 
I have an existing Apache Beam project with Java 8, Apache Beam 2.27.0, Maven and Dagger 2.

I migrated this project in Kotlin : Kotlin JDK 8 with version 1.5.0.

I used the 1.5.0 version of Kotlin because the 1.4.3 had an issue with Beam and Maven plugin (Could not read class: VirtualFile : [https://stackoverflow.com/questions/66170900/kotlin-1-4-30-apache-beam-compilation-error])

Everything seems to be good except the use of native MapElement or FlatMapElement with Typedescriptor and lambda expression.

A part of my pom.xml file

 

{{{code:xml}}}

<properties>
 <beam.version>2.27.0</beam.version>

<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
 <kotlin.code.style>official</kotlin.code.style>
 <kotlin.compiler.jvmTarget>1.8</kotlin.compiler.jvmTarget>
 <kotlin.compiler.incremental>true</kotlin.compiler.incremental>

<kotlin.version>1.5.0</kotlin.version>
 <serialization.version>1.2.0</serialization.version>
 <java.version>1.8</java.version>

<dagger.version>2.35.1</dagger.version>
 <maven-compiler-plugin.version>3.7.0</maven-compiler-plugin.version>
 <maven-exec-plugin.version>1.6.0</maven-exec-plugin.version>
 <maven-surefire-plugin.version>3.0.0-M5</maven-surefire-plugin.version>
 <properties>

<dependencies>
 <dependency>
 <groupId>org.jetbrains.kotlin</groupId>
 <artifactId>kotlin-stdlib-jdk8</artifactId>
 <version>${kotlin.version}</version>
 </dependency>
 <dependency>
 <groupId>org.jetbrains.kotlinx</groupId>
 <artifactId>kotlinx-serialization-json</artifactId>
 <version>${serialization.version}</version>
 </dependency>

<dependency>
 <groupId>org.apache.beam</groupId>
 <artifactId>beam-runners-google-cloud-dataflow-java</artifactId>
 <version>${beam.version}</version>
 <scope>runtime</scope>
 </dependency>

<dependency>
 <groupId>org.apache.beam</groupId>
 <artifactId>beam-sdks-java-core</artifactId>
 <version>${beam.version}</version>
 </dependency>

<dependency>
 <groupId>org.apache.beam</groupId>
 <artifactId>beam-sdks-java-io-google-cloud-platform</artifactId>
 <version>${beam.version}</version>
 </dependency>

<dependency>
 <groupId>org.apache.beam</groupId>
 <artifactId>beam-sdks-java-io-redis</artifactId>
 <version>${beam.version}</version>
 </dependency>
 <dependency>
 <groupId>org.jetbrains.kotlin</groupId>
 <artifactId>kotlin-test-junit</artifactId>
 <version>${kotlin.version}</version>
 <scope>test</scope>
 </dependency>
 <dependencies>

<build>
 <plugins>

<plugin>
 <groupId>org.jetbrains.kotlin</groupId>
 <artifactId>kotlin-maven-plugin</artifactId>
 <version>${kotlin.version}</version>
 <executions>
 <execution>
 <id>kapt</id>
 <goals>
 <goal>kapt</goal>
 </goals>
 <configuration>
 <sourceDirs>
 <sourceDir>src/main/kotlin</sourceDir>
 </sourceDirs>
 <annotationProcessorPaths>
 <annotationProcessorPath>
 <groupId>com.google.dagger</groupId>
 <artifactId>dagger-compiler</artifactId>
 <version>${dagger.version}</version>
 </annotationProcessorPath>
 </annotationProcessorPaths>
 </configuration>
 </execution>
 <execution>
 <id>compile</id>
 <phase>process-sources</phase>
 <goals>
 <goal>compile</goal>
 </goals>
 <configuration>
 <sourceDirs>
 <sourceDir>src/main/kotlin</sourceDir>
 </sourceDirs>
 </configuration>
 </execution>

<execution>
 <id>test-kapt</id>
 <goals>
 <goal>test-kapt</goal>
 </goals>
 <configuration>
 <sourceDirs>
 <sourceDir>src/test/kotlin</sourceDir>
 </sourceDirs>
 <annotationProcessorPaths>
 <annotationProcessorPath>
 <groupId>com.google.dagger</groupId>
 <artifactId>dagger-compiler</artifactId>
 <version>${dagger.version}</version>
 </annotationProcessorPath>
 </annotationProcessorPaths>
 </configuration>
 </execution>
 <execution>
 <id>test-compile</id>
 <goals>
 <goal>test-compile</goal>
 </goals>
 <configuration>
 <sourceDirs>
 <sourceDir>src/test/kotlin</sourceDir>
 <sourceDir>target/generated-sources/kapt/test</sourceDir>
 </sourceDirs>
 </configuration>
 </execution>
 </executions>
 <configuration>
 <compilerPlugins>
 <plugin>kotlinx-serialization</plugin>
 </compilerPlugins>
 </configuration>
 <dependencies>
 <dependency>
 <groupId>org.jetbrains.kotlin</groupId>
 <artifactId>kotlin-maven-serialization</artifactId>
 <version>${kotlin.version}</version>
 </dependency>
 </dependencies>
 </plugin>

<plugin>
 <groupId>org.apache.maven.plugins</groupId>
 <artifactId>maven-surefire-plugin</artifactId>
 <version>${maven-surefire-plugin.version}</version>
 <dependencies>
 <dependency>
 <groupId>org.apache.maven.surefire</groupId>
 <artifactId>surefire-junit47</artifactId>
 <version>${maven-surefire-plugin.version}</version>
 </dependency>
 </dependencies>
 </plugin>

<plugin>
 <groupId>org.codehaus.mojo</groupId>
 <artifactId>exec-maven-plugin</artifactId>
 <version>${maven-exec-plugin.version}</version>
 <configuration>
 <cleanupDaemonThreads>false</cleanupDaemonThreads>
 </configuration>
 </plugin>
 </plugins>

 {{{code}}}

 

An object that implements Serializable (java.io)

 

{{{code:kotlin}}}

data class MyObject(
 val field: String = ""
 ) : Serializable {

{{{code}}}

And basically i want to execute a FlatMapElement with Typedescriptor and a lambda (behind the scene a SerializableFunction)

 

{{{code:kotlin}}}

class MyTransform(private val redisConnectionConf: RedisConnectionConfiguration) :
 PTransform<PBegin, PCollection<MyObject>>() {

override fun expand(input: PBegin): PCollection<MyObject>

{ return input .apply(RedisIO.read().withConnectionConfiguration(redisConnectionConf).withKeyPattern("my-pattern*")) .apply( FlatMapElements.into(of(MyObject::class.java)) .via(SerializableFunction<KV<String, String>, List<MyObject>> \\{ toMyObjects(it) }

)
 )
 }

fun toMyObjects(entry: KV<String, String>): List<MyObject> {
 val key = entry.key
 val value = entry.value

val ref = object : TypeReference<List<MyObject>>() {}
 return OBJECT_MAPPER.readValue(value, ref)
 }

{{{code}}}

I volontary changed the code and put some part of code in method "toMyObjects" in order to give the maximum of elements.
 The "OBJECT_MAPPER" object is a Jackson Object Mapper.

With Java 8 and Beam 2.27.0 this basic code works perfectly fine.

With Kotlin this code doesn't works with the following error :

{{{code:text}}}
 at org.apache.beam.sdk.util.SerializableUtils.serializeToByteArray (SerializableUtils.java:59)
 at org.apache.beam.runners.core.construction.ParDoTranslation.translateDoFn (ParDoTranslation.java:692)
 at org.apache.beam.runners.dataflow.PrimitiveParDoSingleFactory$PayloadTranslator$1.translateDoFn (PrimitiveParDoSingleFactory.java:218)
 at org.apache.beam.runners.core.construction.ParDoTranslation.payloadForParDoLike (ParDoTranslation.java:814)
 at org.apache.beam.runners.dataflow.PrimitiveParDoSingleFactory$PayloadTranslator.payloadForParDoSingle (PrimitiveParDoSingleFactory.java:214)
 at org.apache.beam.runners.dataflow.PrimitiveParDoSingleFactory$PayloadTranslator.translate (PrimitiveParDoSingleFactory.java:163)
 at org.apache.beam.runners.core.construction.PTransformTranslation$KnownTransformPayloadTranslator.translate (PTransformTranslation.java:429)
 at org.apache.beam.runners.core.construction.PTransformTranslation.toProto (PTransformTranslation.java:239)
 at org.apache.beam.runners.core.construction.SdkComponents.registerPTransform (SdkComponents.java:175)
 at org.apache.beam.runners.core.construction.PipelineTranslation$1.visitPrimitiveTransform (PipelineTranslation.java:87)
 at org.apache.beam.sdk.runners.TransformHierarchy$Node.visit (TransformHierarchy.java:587)
 at org.apache.beam.sdk.runners.TransformHierarchy$Node.visit (TransformHierarchy.java:579)
 at org.apache.beam.sdk.runners.TransformHierarchy$Node.visit (TransformHierarchy.java:579)
 at org.apache.beam.sdk.runners.TransformHierarchy$Node.visit (TransformHierarchy.java:579)
 at org.apache.beam.sdk.runners.TransformHierarchy$Node.access$500 (TransformHierarchy.java:239)
 at org.apache.beam.sdk.runners.TransformHierarchy.visit (TransformHierarchy.java:213)
 at org.apache.beam.sdk.Pipeline.traverseTopologically (Pipeline.java:468)
 at org.apache.beam.runners.core.construction.PipelineTranslation.toProto (PipelineTranslation.java:59)
 at org.apache.beam.runners.dataflow.DataflowRunner.run (DataflowRunner.java:933)
 at org.apache.beam.runners.dataflow.DataflowRunner.run (DataflowRunner.java:196)
 at org.apache.beam.sdk.Pipeline.run (Pipeline.java:322)
 at org.apache.beam.sdk.Pipeline.run (Pipeline.java:308)
 at myPackage.MyApp.main (MyApp.kt:44)
 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 org.codehaus.mojo.exec.ExecJavaMojo$1.run (ExecJavaMojo.java:282)
 at java.lang.Thread.run (Thread.java:748)
 Caused by: java.io.NotSerializableException: Non-serializable lambda
 at mypackage.MyTransform$$Lambda$783/1784079343.writeObject (Unknown Source)

[ERROR] Failed to execute goal org.codehaus.mojo:exec-maven-plugin:1.6.0:java (default-cli) on project my-project: 
 An exception occured while executing the Java class. unable to serialize 
 DoFnWithExecutionInformation{doFn=org.apache.beam.sdk.transforms.FlatMapElements$2@23402e70,
 mainOutputTag=Tag<org.apache.beam.sdk.values.PCollection.<init>:402#6929f09b03d242ca>, sideInputMapping={}, schemaInformation=DoFnSchemaInformation\{elementConverters=[]}}: Non-serializable lambda -> [Help 1]

{{{code:text}}}

{{}}

The SerializableUtils.serializeToByteArray method in Beam sdk sends this error : java.io.NotSerializableException: Non-serializable lambda

MyObject is Serializable and the lambda is wrapped in a Beam SerializableFunction (function that implements Serializable).

Normally in this case, Beam take a SerializableCoder from the Serializable object.
 I don't understand why Beam saw the lambda as non Serializable.

I don't have this kind of behaviour directly in Java.

I precise, if i replace the FlatMapElement/descriptor/lambda by a ParDo.of(DoFn), this works fine, but in some cases for a better concision and readabilty, i want to use the built in MapElement and FlatMapElement with lambda expressions.

Thanks in advance for your help.

  was:
I have an existing Apache Beam project with Java 8, Apache Beam 2.27.0, Maven and Dagger 2.

I migrated this project in Kotlin : Kotlin JDK 8 with version 1.5.0.

I used the 1.5.0 version of Kotlin because the 1.4.3 had an issue with Beam and Maven plugin (Could not read class: VirtualFile : https://stackoverflow.com/questions/66170900/kotlin-1-4-30-apache-beam-compilation-error)

Everything seems to be good except the use of native MapElement or FlatMapElement with Typedescriptor and lambda expression.

A part of my pom.xml file

```xml
<properties>
 <beam.version>2.27.0</beam.version>

<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
 <kotlin.code.style>official</kotlin.code.style>
 <kotlin.compiler.jvmTarget>1.8</kotlin.compiler.jvmTarget>
 <kotlin.compiler.incremental>true</kotlin.compiler.incremental>

<kotlin.version>1.5.0</kotlin.version>
 <serialization.version>1.2.0</serialization.version>
 <java.version>1.8</java.version>
 
 <dagger.version>2.35.1</dagger.version>
 <maven-compiler-plugin.version>3.7.0</maven-compiler-plugin.version>
 <maven-exec-plugin.version>1.6.0</maven-exec-plugin.version>
 <maven-surefire-plugin.version>3.0.0-M5</maven-surefire-plugin.version>
<properties>


<dependencies>
 <dependency>
 <groupId>org.jetbrains.kotlin</groupId>
 <artifactId>kotlin-stdlib-jdk8</artifactId>
 <version>${kotlin.version}</version>
 </dependency>
 <dependency>
 <groupId>org.jetbrains.kotlinx</groupId>
 <artifactId>kotlinx-serialization-json</artifactId>
 <version>${serialization.version}</version>
 </dependency>
 
 <dependency>
 <groupId>org.apache.beam</groupId>
 <artifactId>beam-runners-google-cloud-dataflow-java</artifactId>
 <version>${beam.version}</version>
 <scope>runtime</scope>
 </dependency>

<dependency>
 <groupId>org.apache.beam</groupId>
 <artifactId>beam-sdks-java-core</artifactId>
 <version>${beam.version}</version>
 </dependency>

<dependency>
 <groupId>org.apache.beam</groupId>
 <artifactId>beam-sdks-java-io-google-cloud-platform</artifactId>
 <version>${beam.version}</version>
 </dependency>

<dependency>
 <groupId>org.apache.beam</groupId>
 <artifactId>beam-sdks-java-io-redis</artifactId>
 <version>${beam.version}</version>
 </dependency>
 <dependency>
 <groupId>org.jetbrains.kotlin</groupId>
 <artifactId>kotlin-test-junit</artifactId>
 <version>${kotlin.version}</version>
 <scope>test</scope>
 </dependency>
<dependencies>

<build>
 <plugins>

<plugin>
 <groupId>org.jetbrains.kotlin</groupId>
 <artifactId>kotlin-maven-plugin</artifactId>
 <version>${kotlin.version}</version>
 <executions>
 <execution>
 <id>kapt</id>
 <goals>
 <goal>kapt</goal>
 </goals>
 <configuration>
 <sourceDirs>
 <sourceDir>src/main/kotlin</sourceDir>
 </sourceDirs>
 <annotationProcessorPaths>
 <annotationProcessorPath>
 <groupId>com.google.dagger</groupId>
 <artifactId>dagger-compiler</artifactId>
 <version>${dagger.version}</version>
 </annotationProcessorPath>
 </annotationProcessorPaths>
 </configuration>
 </execution>
 <execution>
 <id>compile</id>
 <phase>process-sources</phase>
 <goals>
 <goal>compile</goal>
 </goals>
 <configuration>
 <sourceDirs>
 <sourceDir>src/main/kotlin</sourceDir>
 </sourceDirs>
 </configuration>
 </execution>

<execution>
 <id>test-kapt</id>
 <goals>
 <goal>test-kapt</goal>
 </goals>
 <configuration>
 <sourceDirs>
 <sourceDir>src/test/kotlin</sourceDir>
 </sourceDirs>
 <annotationProcessorPaths>
 <annotationProcessorPath>
 <groupId>com.google.dagger</groupId>
 <artifactId>dagger-compiler</artifactId>
 <version>${dagger.version}</version>
 </annotationProcessorPath>
 </annotationProcessorPaths>
 </configuration>
 </execution>
 <execution>
 <id>test-compile</id>
 <goals>
 <goal>test-compile</goal>
 </goals>
 <configuration>
 <sourceDirs>
 <sourceDir>src/test/kotlin</sourceDir>
 <sourceDir>target/generated-sources/kapt/test</sourceDir>
 </sourceDirs>
 </configuration>
 </execution>
 </executions>
 <configuration>
 <compilerPlugins>
 <plugin>kotlinx-serialization</plugin>
 </compilerPlugins>
 </configuration>
 <dependencies>
 <dependency>
 <groupId>org.jetbrains.kotlin</groupId>
 <artifactId>kotlin-maven-serialization</artifactId>
 <version>${kotlin.version}</version>
 </dependency>
 </dependencies>
 </plugin>
 
 <plugin>
 <groupId>org.apache.maven.plugins</groupId>
 <artifactId>maven-surefire-plugin</artifactId>
 <version>${maven-surefire-plugin.version}</version>
 <dependencies>
 <dependency>
 <groupId>org.apache.maven.surefire</groupId>
 <artifactId>surefire-junit47</artifactId>
 <version>${maven-surefire-plugin.version}</version>
 </dependency>
 </dependencies>
 </plugin>

<plugin>
 <groupId>org.codehaus.mojo</groupId>
 <artifactId>exec-maven-plugin</artifactId>
 <version>${maven-exec-plugin.version}</version>
 <configuration>
 <cleanupDaemonThreads>false</cleanupDaemonThreads>
 </configuration>
 </plugin>
 </plugins>

```

An object that implements Serializable (java.io)

```kotlin
data class MyObject(
 val field: String = ""
) : Serializable {
```

And basically i want to execute a FlatMapElement with Typedescriptor and a lambda (behind the scene a SerializableFunction)

```kotlin
class MyTransform(private val redisConnectionConf: RedisConnectionConfiguration) :
 PTransform<PBegin, PCollection<MyObject>>() {

override fun expand(input: PBegin): PCollection<MyObject> {
 return input
 .apply(RedisIO.read().withConnectionConfiguration(redisConnectionConf).withKeyPattern("my-pattern*"))
 .apply(
 FlatMapElements.into(of(MyObject::class.java))
 .via(SerializableFunction<KV<String, String>, List<MyObject>> \{ toMyObjects(it) })
 )
 }

fun toMyObjects(entry: KV<String, String>): List<MyObject> {
 val key = entry.key
 val value = entry.value
 
 val ref = object : TypeReference<List<MyObject>>() {}
 return OBJECT_MAPPER.readValue(value, ref)
 }
```

I volontary changed the code and put some part of code in method "toMyObjects" in order to give the maximum of elements.
The "OBJECT_MAPPER" object is a Jackson Object Mapper.

With Java 8 and Beam 2.27.0 this basic code works perfectly fine.

With Kotlin this code doesn't works with the following error :

```text
at org.apache.beam.sdk.util.SerializableUtils.serializeToByteArray (SerializableUtils.java:59)
 at org.apache.beam.runners.core.construction.ParDoTranslation.translateDoFn (ParDoTranslation.java:692)
 at org.apache.beam.runners.dataflow.PrimitiveParDoSingleFactory$PayloadTranslator$1.translateDoFn (PrimitiveParDoSingleFactory.java:218)
 at org.apache.beam.runners.core.construction.ParDoTranslation.payloadForParDoLike (ParDoTranslation.java:814)
 at org.apache.beam.runners.dataflow.PrimitiveParDoSingleFactory$PayloadTranslator.payloadForParDoSingle (PrimitiveParDoSingleFactory.java:214)
 at org.apache.beam.runners.dataflow.PrimitiveParDoSingleFactory$PayloadTranslator.translate (PrimitiveParDoSingleFactory.java:163)
 at org.apache.beam.runners.core.construction.PTransformTranslation$KnownTransformPayloadTranslator.translate (PTransformTranslation.java:429)
 at org.apache.beam.runners.core.construction.PTransformTranslation.toProto (PTransformTranslation.java:239)
 at org.apache.beam.runners.core.construction.SdkComponents.registerPTransform (SdkComponents.java:175)
 at org.apache.beam.runners.core.construction.PipelineTranslation$1.visitPrimitiveTransform (PipelineTranslation.java:87)
 at org.apache.beam.sdk.runners.TransformHierarchy$Node.visit (TransformHierarchy.java:587)
 at org.apache.beam.sdk.runners.TransformHierarchy$Node.visit (TransformHierarchy.java:579)
 at org.apache.beam.sdk.runners.TransformHierarchy$Node.visit (TransformHierarchy.java:579)
 at org.apache.beam.sdk.runners.TransformHierarchy$Node.visit (TransformHierarchy.java:579)
 at org.apache.beam.sdk.runners.TransformHierarchy$Node.access$500 (TransformHierarchy.java:239)
 at org.apache.beam.sdk.runners.TransformHierarchy.visit (TransformHierarchy.java:213)
 at org.apache.beam.sdk.Pipeline.traverseTopologically (Pipeline.java:468)
 at org.apache.beam.runners.core.construction.PipelineTranslation.toProto (PipelineTranslation.java:59)
 at org.apache.beam.runners.dataflow.DataflowRunner.run (DataflowRunner.java:933)
 at org.apache.beam.runners.dataflow.DataflowRunner.run (DataflowRunner.java:196)
 at org.apache.beam.sdk.Pipeline.run (Pipeline.java:322)
 at org.apache.beam.sdk.Pipeline.run (Pipeline.java:308)
 at myPackage.MyApp.main (MyApp.kt:44)
 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 org.codehaus.mojo.exec.ExecJavaMojo$1.run (ExecJavaMojo.java:282)
 at java.lang.Thread.run (Thread.java:748)
Caused by: java.io.NotSerializableException: Non-serializable lambda
 at mypackage.MyTransform$$Lambda$783/1784079343.writeObject (Unknown Source)


[ERROR] Failed to execute goal org.codehaus.mojo:exec-maven-plugin:1.6.0:java (default-cli) on project my-project: 
An exception occured while executing the Java class. unable to serialize 
DoFnWithExecutionInformation{doFn=org.apache.beam.sdk.transforms.FlatMapElements$2@23402e70,
mainOutputTag=Tag<org.apache.beam.sdk.values.PCollection.<init>:402#6929f09b03d242ca>, sideInputMapping={}, schemaInformation=DoFnSchemaInformation\{elementConverters=[]}}: Non-serializable lambda -> [Help 1]
```

The SerializableUtils.serializeToByteArray method in Beam sdk sends this error : java.io.NotSerializableException: Non-serializable lambda

MyObject is Serializable and the lambda is wrapped in a Beam SerializableFunction (function that implements Serializable).

Normally in this case, Beam take a SerializableCoder from the Serializable object.
I don't understand why Beam saw the lambda as non Serializable.

I don't have this kind of behaviour directly in Java.

I precise, if i replace the FlatMapElement/descriptor/lambda by a ParDo.of(DoFn), this works fine, but in some cases for a better concision and readabilty, i want to use the built in MapElement and FlatMapElement with lambda expressions.


Thanks in advance for your help.


> FlatMapElement Kotlin Beam non Serializable lambda
> --------------------------------------------------
>
>                 Key: BEAM-12265
>                 URL: https://issues.apache.org/jira/browse/BEAM-12265
>             Project: Beam
>          Issue Type: Bug
>          Components: beam-community
>            Reporter: Mazlum Tosun
>            Priority: P0
>             Fix For: 2.27.0
>
>
> I have an existing Apache Beam project with Java 8, Apache Beam 2.27.0, Maven and Dagger 2.
> I migrated this project in Kotlin : Kotlin JDK 8 with version 1.5.0.
> I used the 1.5.0 version of Kotlin because the 1.4.3 had an issue with Beam and Maven plugin (Could not read class: VirtualFile : [https://stackoverflow.com/questions/66170900/kotlin-1-4-30-apache-beam-compilation-error])
> Everything seems to be good except the use of native MapElement or FlatMapElement with Typedescriptor and lambda expression.
> A part of my pom.xml file
>  
> {{{code:xml}}}
> <properties>
>  <beam.version>2.27.0</beam.version>
> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
>  <kotlin.code.style>official</kotlin.code.style>
>  <kotlin.compiler.jvmTarget>1.8</kotlin.compiler.jvmTarget>
>  <kotlin.compiler.incremental>true</kotlin.compiler.incremental>
> <kotlin.version>1.5.0</kotlin.version>
>  <serialization.version>1.2.0</serialization.version>
>  <java.version>1.8</java.version>
> <dagger.version>2.35.1</dagger.version>
>  <maven-compiler-plugin.version>3.7.0</maven-compiler-plugin.version>
>  <maven-exec-plugin.version>1.6.0</maven-exec-plugin.version>
>  <maven-surefire-plugin.version>3.0.0-M5</maven-surefire-plugin.version>
>  <properties>
> <dependencies>
>  <dependency>
>  <groupId>org.jetbrains.kotlin</groupId>
>  <artifactId>kotlin-stdlib-jdk8</artifactId>
>  <version>${kotlin.version}</version>
>  </dependency>
>  <dependency>
>  <groupId>org.jetbrains.kotlinx</groupId>
>  <artifactId>kotlinx-serialization-json</artifactId>
>  <version>${serialization.version}</version>
>  </dependency>
> <dependency>
>  <groupId>org.apache.beam</groupId>
>  <artifactId>beam-runners-google-cloud-dataflow-java</artifactId>
>  <version>${beam.version}</version>
>  <scope>runtime</scope>
>  </dependency>
> <dependency>
>  <groupId>org.apache.beam</groupId>
>  <artifactId>beam-sdks-java-core</artifactId>
>  <version>${beam.version}</version>
>  </dependency>
> <dependency>
>  <groupId>org.apache.beam</groupId>
>  <artifactId>beam-sdks-java-io-google-cloud-platform</artifactId>
>  <version>${beam.version}</version>
>  </dependency>
> <dependency>
>  <groupId>org.apache.beam</groupId>
>  <artifactId>beam-sdks-java-io-redis</artifactId>
>  <version>${beam.version}</version>
>  </dependency>
>  <dependency>
>  <groupId>org.jetbrains.kotlin</groupId>
>  <artifactId>kotlin-test-junit</artifactId>
>  <version>${kotlin.version}</version>
>  <scope>test</scope>
>  </dependency>
>  <dependencies>
> <build>
>  <plugins>
> <plugin>
>  <groupId>org.jetbrains.kotlin</groupId>
>  <artifactId>kotlin-maven-plugin</artifactId>
>  <version>${kotlin.version}</version>
>  <executions>
>  <execution>
>  <id>kapt</id>
>  <goals>
>  <goal>kapt</goal>
>  </goals>
>  <configuration>
>  <sourceDirs>
>  <sourceDir>src/main/kotlin</sourceDir>
>  </sourceDirs>
>  <annotationProcessorPaths>
>  <annotationProcessorPath>
>  <groupId>com.google.dagger</groupId>
>  <artifactId>dagger-compiler</artifactId>
>  <version>${dagger.version}</version>
>  </annotationProcessorPath>
>  </annotationProcessorPaths>
>  </configuration>
>  </execution>
>  <execution>
>  <id>compile</id>
>  <phase>process-sources</phase>
>  <goals>
>  <goal>compile</goal>
>  </goals>
>  <configuration>
>  <sourceDirs>
>  <sourceDir>src/main/kotlin</sourceDir>
>  </sourceDirs>
>  </configuration>
>  </execution>
> <execution>
>  <id>test-kapt</id>
>  <goals>
>  <goal>test-kapt</goal>
>  </goals>
>  <configuration>
>  <sourceDirs>
>  <sourceDir>src/test/kotlin</sourceDir>
>  </sourceDirs>
>  <annotationProcessorPaths>
>  <annotationProcessorPath>
>  <groupId>com.google.dagger</groupId>
>  <artifactId>dagger-compiler</artifactId>
>  <version>${dagger.version}</version>
>  </annotationProcessorPath>
>  </annotationProcessorPaths>
>  </configuration>
>  </execution>
>  <execution>
>  <id>test-compile</id>
>  <goals>
>  <goal>test-compile</goal>
>  </goals>
>  <configuration>
>  <sourceDirs>
>  <sourceDir>src/test/kotlin</sourceDir>
>  <sourceDir>target/generated-sources/kapt/test</sourceDir>
>  </sourceDirs>
>  </configuration>
>  </execution>
>  </executions>
>  <configuration>
>  <compilerPlugins>
>  <plugin>kotlinx-serialization</plugin>
>  </compilerPlugins>
>  </configuration>
>  <dependencies>
>  <dependency>
>  <groupId>org.jetbrains.kotlin</groupId>
>  <artifactId>kotlin-maven-serialization</artifactId>
>  <version>${kotlin.version}</version>
>  </dependency>
>  </dependencies>
>  </plugin>
> <plugin>
>  <groupId>org.apache.maven.plugins</groupId>
>  <artifactId>maven-surefire-plugin</artifactId>
>  <version>${maven-surefire-plugin.version}</version>
>  <dependencies>
>  <dependency>
>  <groupId>org.apache.maven.surefire</groupId>
>  <artifactId>surefire-junit47</artifactId>
>  <version>${maven-surefire-plugin.version}</version>
>  </dependency>
>  </dependencies>
>  </plugin>
> <plugin>
>  <groupId>org.codehaus.mojo</groupId>
>  <artifactId>exec-maven-plugin</artifactId>
>  <version>${maven-exec-plugin.version}</version>
>  <configuration>
>  <cleanupDaemonThreads>false</cleanupDaemonThreads>
>  </configuration>
>  </plugin>
>  </plugins>
>  {{{code}}}
>  
> An object that implements Serializable (java.io)
>  
> {{{code:kotlin}}}
> data class MyObject(
>  val field: String = ""
>  ) : Serializable {
> {{{code}}}
> And basically i want to execute a FlatMapElement with Typedescriptor and a lambda (behind the scene a SerializableFunction)
>  
> {{{code:kotlin}}}
> class MyTransform(private val redisConnectionConf: RedisConnectionConfiguration) :
>  PTransform<PBegin, PCollection<MyObject>>() {
> override fun expand(input: PBegin): PCollection<MyObject>
> { return input .apply(RedisIO.read().withConnectionConfiguration(redisConnectionConf).withKeyPattern("my-pattern*")) .apply( FlatMapElements.into(of(MyObject::class.java)) .via(SerializableFunction<KV<String, String>, List<MyObject>> \\{ toMyObjects(it) }
> )
>  )
>  }
> fun toMyObjects(entry: KV<String, String>): List<MyObject> {
>  val key = entry.key
>  val value = entry.value
> val ref = object : TypeReference<List<MyObject>>() {}
>  return OBJECT_MAPPER.readValue(value, ref)
>  }
> {{{code}}}
> I volontary changed the code and put some part of code in method "toMyObjects" in order to give the maximum of elements.
>  The "OBJECT_MAPPER" object is a Jackson Object Mapper.
> With Java 8 and Beam 2.27.0 this basic code works perfectly fine.
> With Kotlin this code doesn't works with the following error :
> {{{code:text}}}
>  at org.apache.beam.sdk.util.SerializableUtils.serializeToByteArray (SerializableUtils.java:59)
>  at org.apache.beam.runners.core.construction.ParDoTranslation.translateDoFn (ParDoTranslation.java:692)
>  at org.apache.beam.runners.dataflow.PrimitiveParDoSingleFactory$PayloadTranslator$1.translateDoFn (PrimitiveParDoSingleFactory.java:218)
>  at org.apache.beam.runners.core.construction.ParDoTranslation.payloadForParDoLike (ParDoTranslation.java:814)
>  at org.apache.beam.runners.dataflow.PrimitiveParDoSingleFactory$PayloadTranslator.payloadForParDoSingle (PrimitiveParDoSingleFactory.java:214)
>  at org.apache.beam.runners.dataflow.PrimitiveParDoSingleFactory$PayloadTranslator.translate (PrimitiveParDoSingleFactory.java:163)
>  at org.apache.beam.runners.core.construction.PTransformTranslation$KnownTransformPayloadTranslator.translate (PTransformTranslation.java:429)
>  at org.apache.beam.runners.core.construction.PTransformTranslation.toProto (PTransformTranslation.java:239)
>  at org.apache.beam.runners.core.construction.SdkComponents.registerPTransform (SdkComponents.java:175)
>  at org.apache.beam.runners.core.construction.PipelineTranslation$1.visitPrimitiveTransform (PipelineTranslation.java:87)
>  at org.apache.beam.sdk.runners.TransformHierarchy$Node.visit (TransformHierarchy.java:587)
>  at org.apache.beam.sdk.runners.TransformHierarchy$Node.visit (TransformHierarchy.java:579)
>  at org.apache.beam.sdk.runners.TransformHierarchy$Node.visit (TransformHierarchy.java:579)
>  at org.apache.beam.sdk.runners.TransformHierarchy$Node.visit (TransformHierarchy.java:579)
>  at org.apache.beam.sdk.runners.TransformHierarchy$Node.access$500 (TransformHierarchy.java:239)
>  at org.apache.beam.sdk.runners.TransformHierarchy.visit (TransformHierarchy.java:213)
>  at org.apache.beam.sdk.Pipeline.traverseTopologically (Pipeline.java:468)
>  at org.apache.beam.runners.core.construction.PipelineTranslation.toProto (PipelineTranslation.java:59)
>  at org.apache.beam.runners.dataflow.DataflowRunner.run (DataflowRunner.java:933)
>  at org.apache.beam.runners.dataflow.DataflowRunner.run (DataflowRunner.java:196)
>  at org.apache.beam.sdk.Pipeline.run (Pipeline.java:322)
>  at org.apache.beam.sdk.Pipeline.run (Pipeline.java:308)
>  at myPackage.MyApp.main (MyApp.kt:44)
>  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 org.codehaus.mojo.exec.ExecJavaMojo$1.run (ExecJavaMojo.java:282)
>  at java.lang.Thread.run (Thread.java:748)
>  Caused by: java.io.NotSerializableException: Non-serializable lambda
>  at mypackage.MyTransform$$Lambda$783/1784079343.writeObject (Unknown Source)
> [ERROR] Failed to execute goal org.codehaus.mojo:exec-maven-plugin:1.6.0:java (default-cli) on project my-project: 
>  An exception occured while executing the Java class. unable to serialize 
>  DoFnWithExecutionInformation{doFn=org.apache.beam.sdk.transforms.FlatMapElements$2@23402e70,
>  mainOutputTag=Tag<org.apache.beam.sdk.values.PCollection.<init>:402#6929f09b03d242ca>, sideInputMapping={}, schemaInformation=DoFnSchemaInformation\{elementConverters=[]}}: Non-serializable lambda -> [Help 1]
> {{{code:text}}}
> {{}}
> The SerializableUtils.serializeToByteArray method in Beam sdk sends this error : java.io.NotSerializableException: Non-serializable lambda
> MyObject is Serializable and the lambda is wrapped in a Beam SerializableFunction (function that implements Serializable).
> Normally in this case, Beam take a SerializableCoder from the Serializable object.
>  I don't understand why Beam saw the lambda as non Serializable.
> I don't have this kind of behaviour directly in Java.
> I precise, if i replace the FlatMapElement/descriptor/lambda by a ParDo.of(DoFn), this works fine, but in some cases for a better concision and readabilty, i want to use the built in MapElement and FlatMapElement with lambda expressions.
> Thanks in advance for your help.



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