我如何在flink中使用joda.time（或者我如何使用typeutils.runtime.kryo）

Question

在一个flink项目中，我使用一个case类click。

case class click( date: LocalDateTime, stbId:String, channelId :Int)

这个类填充了数据集，并且在日期为Java8java.time.localdatetime的情况下可以很好地工作。在Java7环境中切换到org.joda(Version2.9)之后，对数据集中的click对象的调用不像以前那样执行。对click对象的date字段的某些函数的访问引发NullPointerExceptions。这些函数的例子有gethorofdaytoString等。我能够确保click类的日期字段不为空。我怀疑joda时间库与kryo序列化的交互不是很好。参见joda DateTime格式导致spark RDD函数中的null指针错误或spark中的NPE。在Flink API中有org.apache.Flink.API.java.typeutils.runtime.kryo.Serializers和静态方法registerjodatime。这似乎是相关的。我很用心地试着

import  org.apache.flink.api.common._
import org.apache.flink.api.java.typeutils.runtime.kryo._
Serializers.registerJodaTime(new ExecutionConfig)

这还不够。我这样做对吗？我如何使用java.typeutils.runtime.kryo？

使用的版本Flink:0.9.1.scala:2.10Joda.×2.9

跟进：下面是所建议的添加代码（感谢Fabian和Robert）

val env = ExecutionEnvironment.getExecutionEnvironment
//import  org.apache.flink.api.common._
import org.apache.flink.api.java.typeutils.runtime.kryo._
Serializers.registerJodaTime(env.getConfig)

16:44:53,998 INFO  org.apache.flink.api.java.ExecutionEnvironment                - The job has 2 registered types and 0 default Kryo serializers
16:44:53,998 DEBUG org.apache.flink.api.java.ExecutionEnvironment                - Registered Kryo types: 
16:44:53,998 DEBUG org.apache.flink.api.java.ExecutionEnvironment                - Registered Kryo with Serializers types: 
16:44:53,998 DEBUG org.apache.flink.api.java.ExecutionEnvironment                - Registered Kryo with Serializer Classes types: Entry{k=class org.joda.time.DateTime, v=class de.javakaffee.kryoserializers.jodatime.JodaDateTimeSerializer},Entry{k=class org.joda.time.Interval, v=class de.javakaffee.kryoserializers.jodatime.JodaIntervalSerializer}
16:44:53,998 DEBUG org.apache.flink.api.java.ExecutionEnvironment                - Registered Kryo default Serializers: 
16:44:53,998 DEBUG org.apache.flink.api.java.ExecutionEnvironment                - Registered Kryo default Serializers Classes 
16:44:53,998 DEBUG org.apache.flink.api.java.ExecutionEnvironment                - Registered POJO types: 
16:44:53,998 DEBUG org.apache.flink.api.java.ExecutionEnvironment                - Static code analysis mode: DISABLE
16:44:54,545 INFO  akka.event.slf4j.Slf4jLogger                                  - Slf4jLogger started
16:44:54,560 DEBUG akka.event.EventStream                                        - logger log1-Slf4jLogger started
....
16:44:57,103 DEBUG org.apache.flink.api.java.typeutils.TypeExtractor             - class org.joda.time.LocalDateTime does not contain a getter for field iLocalMillis
16:44:57,103 DEBUG org.apache.flink.api.java.typeutils.TypeExtractor             - class org.joda.time.LocalDateTime does not contain a setter for field iLocalMillis
16:44:57,103 INFO  org.apache.flink.api.java.typeutils.TypeExtractor                 - class org.joda.time.LocalDateTime is not a valid POJO type
16:44:57,275 DEBUG org.apache.flink.api.scala.ClosureCleaner$                        - accessedFields: Map()
16:44:57,369 INFO  org.apache.flink.api.java.ExecutionEnvironment                - The job has 2 registered types and 0 default Kryo serializers
16:44:57,369 DEBUG org.apache.flink.api.java.ExecutionEnvironment                - Registered Kryo types: 
16:44:57,369 DEBUG org.apache.flink.api.java.ExecutionEnvironment                - Registered Kryo with Serializers types: 
16:44:57,369 DEBUG org.apache.flink.api.java.ExecutionEnvironment                - Registered Kryo with Serializer Classes types: Entry{k=class org.joda.time.DateTime, v=class de.javakaffee.kryoserializers.jodatime.JodaDateTimeSerializer},Entry{k=class org.joda.time.Interval, v=class de.javakaffee.kryoserializers.jodatime.JodaIntervalSerializer}
16:44:57,369 DEBUG org.apache.flink.api.java.ExecutionEnvironment                - Registered Kryo default Serializers: 
16:44:57,369 DEBUG org.apache.flink.api.java.ExecutionEnvironment                - Registered Kryo default Serializers Classes 
16:44:57,369 DEBUG org.apache.flink.api.java.ExecutionEnvironment                - Registered POJO types: 
16:44:57,369 DEBUG org.apache.flink.api.java.ExecutionEnvironment                - Static code analysis mode: DISABLE

尽管如此，我还是目睹了以下几点

Exception in thread "main" java.lang.NullPointerException
    at org.joda.time.LocalDateTime.isSupported(LocalDateTime.java:625)
    at org.joda.time.format.DateTimeFormatterBuilder$PaddedNumber.printTo(DateTimeFormatterBuilder.java:1435)
    at org.joda.time.format.DateTimeFormatterBuilder$Composite.printTo(DateTimeFormatterBuilder.java:2474)
    at org.joda.time.format.DateTimeFormatter.printTo(DateTimeFormatter.java:655)
    at org.joda.time.format.DateTimeFormatter.print(DateTimeFormatter.java:709)
    at org.joda.time.LocalDateTime.toString(LocalDateTime.java:2087)
    at java.lang.String.valueOf(Unknown Source)
    at scala.runtime.StringAdd$.$plus$extension(StringAdd.scala:13)
    at myflink.click.toString(Ingestor.scala:20)
    ...

Answer 1

Flink将Kryo用于它无法序列化的类型。localdatetime就是这样一个类。

遗憾的是，Kryo也不能正确地序列化它，所以我们不得不告诉Kryo如何通过为这个类提供一个专门的序列化器来实现它。

1. 将de.javakaffee:kryo-serializers添加为依赖项:

<dependency>
    <groupId>de.javakaffee</groupId>
    <artifactId>kryo-serializers</artifactId>
    <version>0.30</version>
</dependency>

val env = ExecutionEnvironment.getExecutionEnvironment
env.registerTypeWithKryoSerializer(classOf[LocalDateTime], classOf[JodaLocalDateTimeSerializer])

我希望这能有所帮助（我保留了以前的答案作为参考）

在Flink中调试KRYO/Serializer问题的一些一般性说明：

在本地执行作业时（也应该在./bin/flink前端中工作，但输出可能在log/目录中），您应该看到如下内容：

14:05:52,863 INFO  org.apache.flink.api.java.ExecutionEnvironment                - The job has 15 registered types and 2 default Kryo serializers 
14:05:52,943 INFO  org.apache.flink.runtime.minicluster.FlinkMiniCluster         - Starting FlinkMiniCluster. 
14:05:53,150 INFO  akka.event.slf4j.Slf4jLogger                                  - Slf4jLogger started

使用调试日志级别（在log4j.properties中将info替换为DEBUG)，您实际上可以获得有关已注册序列化器的更详细信息：

14:10:39,935 DEBUG org.apache.flink.api.java.ExecutionEnvironment                - Registered Kryo types: 
14:10:39,935 DEBUG org.apache.flink.api.java.ExecutionEnvironment                - Registered Kryo with Serializers types: 
14:10:39,935 DEBUG org.apache.flink.api.java.ExecutionEnvironment                - Registered Kryo with Serializer Classes types: 
14:10:39,935 DEBUG org.apache.flink.api.java.ExecutionEnvironment                - Registered Kryo default Serializers: 
14:10:39,935 DEBUG org.apache.flink.api.java.ExecutionEnvironment                - Registered Kryo default Serializers Classes 
14:10:39,935 DEBUG org.apache.flink.api.java.ExecutionEnvironment                - Registered POJO types: