Flink Python数据流API Kafka生产者Sink序列化
您好，我正在尝试从一个卡夫卡主题中读取数据，并在进行一些处理后写入到另一个主题中。
当我试图将数据写入另一个主题时，我能够读取数据并对其进行处理。它会显示错误
如果我尝试按原样写入数据，而不对其进行任何处理。Kafka生产者SimpleStringSchema接受它。 但我想将字符串转换为Json。玩Json，然后以字符串格式将其写入另一个主题。
我的代码：
import json
from pyflink.common import Row
from pyflink.common.serialization import SimpleStringSchema, SerializationSchema,JsonRowSerializationSchema,Encoder
from pyflink.common.typeinfo import Types,BasicType,TypeInformation,BasicTypeInfo
from pyflink.datastream import StreamExecutionEnvironment
from pyflink.datastream.connectors import FlinkKafkaConsumer, FlinkKafkaProducer
def my_map(obj):
json_obj = json.loads(json.loads(obj))
return json.dumps(json_obj["name"])
def utf8_decoder(s):
""" Decode the unicode as UTF-8 """
if s is None:
return None
return s.decode('utf-8')
def datastream_api_demo():
# 1. create a StreamExecutionEnvironment
env = StreamExecutionEnvironment.get_execution_environment()
# the sql connector for kafka is used here as it's a fat jar and could avoid dependency issues
env.add_jars("file:///Users/niaz/Downloads/f2.jar")
# 2. create source DataStream
deserialization_schema = SimpleStringSchema()
# deserialization_schema = JsonRowDeserializationSchema.builder()
# .type_info(type_info=Types.ROW([
# Types.("name", Types.STRING()),
# Types.FIELD("age", Types.LONG()),
# Types.FIELD("car", Types.STRING())])).build()
kafka_source = FlinkKafkaConsumer(
topics='test_source_topic_input',
deserialization_schema=deserialization_schema,
properties={'bootstrap.servers': 'localhost:9092', 'group.id': 'test_group'})
ds = env.add_source(kafka_source)
ds = ds.map(lambda a: my_map(a))
# 3. define the execution logic
# ds = ds.map(lambda a: Row(a % 4, 1), output_type=Types.ROW([Types.LONG(), Types.LONG()]))
# .key_by(lambda a: a[0])
# .reduce(lambda a, b: Row(a[0], a[1] + b[1]))
# 4. create sink and emit result to sink
serialization_schema = SimpleStringSchema()
kafka_sink = FlinkKafkaProducer(
topic='test_sink_topic_4',
serialization_schema=serialization_schema,
producer_config={'bootstrap.servers': 'localhost:9092', 'group.id': 'test_group'})
ds.add_sink(kafka_sink)
#ds.print()
# 5. execute the job
env.execute('datastream_api_demo')
if __name__ == '__main__':
datastream_api_demo()
我收到以下错误：
py4j.protocol.Py4JJavaError: An error occurred while calling o0.execute.
: org.apache.flink.runtime.client.JobExecutionException: Job execution failed.
at org.apache.flink.runtime.jobmaster.JobResult.toJobExecutionResult(JobResult.java:144)
at org.apache.flink.runtime.minicluster.MiniClusterJobClient.lambda$getJobExecutionResult$3(MiniClusterJobClient.java:137)
at java.base/java.util.concurrent.CompletableFuture$UniApply.tryFire(CompletableFuture.java:642)
at java.base/java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:506)
at java.base/java.util.concurrent.CompletableFuture.complete(CompletableFuture.java:2073)
at org.apache.flink.runtime.rpc.akka.AkkaInvocationHandler.lambda$invokeRpc$0(AkkaInvocationHandler.java:237)
at java.base/java.util.concurrent.CompletableFuture.uniWhenComplete(CompletableFuture.java:859)
at java.base/java.util.concurrent.CompletableFuture$UniWhenComplete.tryFire(CompletableFuture.java:837)
at java.base/java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:506)
at java.base/java.util.concurrent.CompletableFuture.complete(CompletableFuture.java:2073)
at org.apache.flink.runtime.concurrent.FutureUtils$1.onComplete(FutureUtils.java:1081)
at akka.dispatch.OnComplete.internal(Future.scala:264)
at akka.dispatch.OnComplete.internal(Future.scala:261)
at akka.dispatch.japi$CallbackBridge.apply(Future.scala:191)
at akka.dispatch.japi$CallbackBridge.apply(Future.scala:188)
at scala.concurrent.impl.CallbackRunnable.run(Promise.scala:36)
at org.apache.flink.runtime.concurrent.Executors$DirectExecutionContext.execute(Executors.java:73)
at scala.concurrent.impl.CallbackRunnable.executeWithValue(Promise.scala:44)
at scala.concurrent.impl.Promise$DefaultPromise.tryComplete(Promise.scala:252)
at akka.pattern.PromiseActorRef.$bang(AskSupport.scala:572)
at akka.pattern.PipeToSupport$PipeableFuture$$anonfun$pipeTo$1.applyOrElse(PipeToSupport.scala:22)
at akka.pattern.PipeToSupport$PipeableFuture$$anonfun$pipeTo$1.applyOrElse(PipeToSupport.scala:21)
at scala.concurrent.Future$$anonfun$andThen$1.apply(Future.scala:436)
at scala.concurrent.Future$$anonfun$andThen$1.apply(Future.scala:435)
at scala.concurrent.impl.CallbackRunnable.run(Promise.scala:36)
at akka.dispatch.BatchingExecutor$AbstractBatch.processBatch(BatchingExecutor.scala:55)
at akka.dispatch.BatchingExecutor$BlockableBatch$$anonfun$run$1.apply$mcV$sp(BatchingExecutor.scala:91)
at akka.dispatch.BatchingExecutor$BlockableBatch$$anonfun$run$1.apply(BatchingExecutor.scala:91)
at akka.dispatch.BatchingExecutor$BlockableBatch$$anonfun$run$1.apply(BatchingExecutor.scala:91)
at scala.concurrent.BlockContext$.withBlockContext(BlockContext.scala:72)
at akka.dispatch.BatchingExecutor$BlockableBatch.run(BatchingExecutor.scala:90)
at akka.dispatch.TaskInvocation.run(AbstractDispatcher.scala:40)
at akka.dispatch.ForkJoinExecutorConfigurator$AkkaForkJoinTask.exec(ForkJoinExecutorConfigurator.scala:44)
at akka.dispatch.forkjoin.ForkJoinTask.doExec(ForkJoinTask.java:260)
at akka.dispatch.forkjoin.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1339)
at akka.dispatch.forkjoin.ForkJoinPool.runWorker(ForkJoinPool.java:1979)
at akka.dispatch.forkjoin.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:107)
Caused by: org.apache.flink.runtime.JobException: Recovery is suppressed by NoRestartBackoffTimeStrategy
at org.apache.flink.runtime.executiongraph.failover.flip1.ExecutionFailureHandler.handleFailure(ExecutionFailureHandler.java:138)
at org.apache.flink.runtime.executiongraph.failover.flip1.ExecutionFailureHandler.getFailureHandlingResult(ExecutionFailureHandler.java:82)
at org.apache.flink.runtime.scheduler.DefaultScheduler.handleTaskFailure(DefaultScheduler.java:216)
at org.apache.flink.runtime.scheduler.DefaultScheduler.maybeHandleTaskFailure(DefaultScheduler.java:206)
at org.apache.flink.runtime.scheduler.DefaultScheduler.updateTaskExecutionStateInternal(DefaultScheduler.java:197)
at org.apache.flink.runtime.scheduler.SchedulerBase.updateTaskExecutionState(SchedulerBase.java:682)
at org.apache.flink.runtime.scheduler.SchedulerNG.updateTaskExecutionState(SchedulerNG.java:79)
at org.apache.flink.runtime.jobmaster.JobMaster.updateTaskExecutionState(JobMaster.java:435)
at jdk.internal.reflect.GeneratedMethodAccessor41.invoke(Unknown Source)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:566)
at org.apache.flink.runtime.rpc.akka.AkkaRpcActor.handleRpcInvocation(AkkaRpcActor.java:305)
at org.apache.flink.runtime.rpc.akka.AkkaRpcActor.handleRpcMessage(AkkaRpcActor.java:212)
at org.apache.flink.runtime.rpc.akka.FencedAkkaRpcActor.handleRpcMessage(FencedAkkaRpcActor.java:77)
at org.apache.flink.runtime.rpc.akka.AkkaRpcActor.handleMessage(AkkaRpcActor.java:158)
at akka.japi.pf.UnitCaseStatement.apply(CaseStatements.scala:26)
at akka.japi.pf.UnitCaseStatement.apply(CaseStatements.scala:21)
at scala.PartialFunction$class.applyOrElse(PartialFunction.scala:123)
at akka.japi.pf.UnitCaseStatement.applyOrElse(CaseStatements.scala:21)
at scala.PartialFunction$OrElse.applyOrElse(PartialFunction.scala:170)
at scala.PartialFunction$OrElse.applyOrElse(PartialFunction.scala:171)
at scala.PartialFunction$OrElse.applyOrElse(PartialFunction.scala:171)
at akka.actor.Actor$class.aroundReceive(Actor.scala:517)
at akka.actor.AbstractActor.aroundReceive(AbstractActor.scala:225)
at akka.actor.ActorCell.receiveMessage(ActorCell.scala:592)
at akka.actor.ActorCell.invoke(ActorCell.scala:561)
at akka.dispatch.Mailbox.processMailbox(Mailbox.scala:258)
at akka.dispatch.Mailbox.run(Mailbox.scala:225)
at akka.dispatch.Mailbox.exec(Mailbox.scala:235)
... 4 more
Caused by: org.apache.flink.streaming.runtime.tasks.AsynchronousException: Caught exception while processing timer.
at org.apache.flink.streaming.runtime.tasks.StreamTask$StreamTaskAsyncExceptionHandler.handleAsyncException(StreamTask.java:1309)
at org.apache.flink.streaming.runtime.tasks.StreamTask.handleAsyncException(StreamTask.java:1285)
at org.apache.flink.streaming.runtime.tasks.StreamTask.invokeProcessingTimeCallback(StreamTask.java:1424)
at org.apache.flink.streaming.runtime.tasks.StreamTask.lambda$null$16(StreamTask.java:1413)
at org.apache.flink.streaming.runtime.tasks.StreamTaskActionExecutor$SynchronizedStreamTaskActionExecutor.runThrowing(StreamTaskActionExecutor.java:93)
at org.apache.flink.streaming.runtime.tasks.mailbox.Mail.run(Mail.java:90)
at org.apache.flink.streaming.runtime.tasks.mailbox.MailboxProcessor.processMailsWhenDefaultActionUnavailable(MailboxProcessor.java:344)
at org.apache.flink.streaming.runtime.tasks.mailbox.MailboxProcessor.processMail(MailboxProcessor.java:330)
at org.apache.flink.streaming.runtime.tasks.mailbox.MailboxProcessor.runMailboxLoop(MailboxProcessor.java:202)
at org.apache.flink.streaming.runtime.tasks.StreamTask.runMailboxLoop(StreamTask.java:681)
at org.apache.flink.streaming.runtime.tasks.StreamTask.executeInvoke(StreamTask.java:636)
at org.apache.flink.streaming.runtime.tasks.StreamTask.runWithCleanUpOnFail(StreamTask.java:647)
at org.apache.flink.streaming.runtime.tasks.StreamTask.invoke(StreamTask.java:620)
at org.apache.flink.runtime.taskmanager.Task.doRun(Task.java:779)
at org.apache.flink.runtime.taskmanager.Task.run(Task.java:566)
at java.base/java.lang.Thread.run(Thread.java:834)
Caused by: TimerException{org.apache.flink.streaming.runtime.tasks.ExceptionInChainedOperatorException: Could not forward element to next operator}
... 14 more
Caused by: org.apache.flink.streaming.runtime.tasks.ExceptionInChainedOperatorException: Could not forward element to next operator
at org.apache.flink.streaming.runtime.tasks.CopyingChainingOutput.pushToOperator(CopyingChainingOutput.java:85)
at org.apache.flink.streaming.runtime.tasks.CopyingChainingOutput.collect(CopyingChainingOutput.java:46)
at org.apache.flink.streaming.runtime.tasks.CopyingChainingOutput.collect(CopyingChainingOutput.java:26)
at org.apache.flink.streaming.api.operators.CountingOutput.collect(CountingOutput.java:50)
at org.apache.flink.streaming.api.operators.CountingOutput.collect(CountingOutput.java:28)
at org.apache.flink.streaming.api.operators.TimestampedCollector.collect(TimestampedCollector.java:50)
at org.apache.flink.streaming.api.operators.python.PythonMapOperator.emitResult(PythonMapOperator.java:59)
at org.apache.flink.streaming.api.operators.python.AbstractPythonFunctionOperator.emitResults(AbstractPythonFunctionOperator.java:299)
at org.apache.flink.streaming.api.operators.python.AbstractPythonFunctionOperator.invokeFinishBundle(AbstractPythonFunctionOperator.java:322)
at org.apache.flink.streaming.api.operators.python.AbstractPythonFunctionOperator.checkInvokeFinishBundleByTime(AbstractPythonFunctionOperator.java:314)
at org.apache.flink.streaming.api.operators.python.AbstractPythonFunctionOperator.lambda$open$0(AbstractPythonFunctionOperator.java:133)
at org.apache.flink.streaming.runtime.tasks.StreamTask.invokeProcessingTimeCallback(StreamTask.java:1422)
... 13 more
Caused by: java.lang.ClassCastException: class [B cannot be cast to class java.lang.String ([B and java.lang.String are in module java.base of loader 'bootstrap')
at org.apache.flink.api.common.serialization.SimpleStringSchema.serialize(SimpleStringSchema.java:36)
at org.apache.flink.streaming.connectors.kafka.internals.KafkaSerializationSchemaWrapper.serialize(KafkaSerializationSchemaWrapper.java:71)
at org.apache.flink.streaming.connectors.kafka.FlinkKafkaProducer.invoke(FlinkKafkaProducer.java:907)
at org.apache.flink.streaming.connectors.kafka.FlinkKafkaProducer.invoke(FlinkKafkaProducer.java:99)
at org.apache.flink.streaming.api.functions.sink.TwoPhaseCommitSinkFunction.invoke(TwoPhaseCommitSinkFunction.java:223)
at org.apache.flink.streaming.api.operators.StreamSink.processElement(StreamSink.java:54)
at org.apache.flink.streaming.runtime.tasks.CopyingChainingOutput.pushToOperator(CopyingChainingOutput.java:71)
... 24 more
解决方案
我已经通过提供类似
的输出类型Java string解决了这个问题 from pyflink.common.typeinfo import Types
ds = ds.map(lambda a: my_map(a),Types.STRING()) # Map function needs ouput type to serialize it to Java String
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