我正在尝试在 python 中构建一个流式光束管道，它应该从 kafka 捕获消息，然后执行从其他来源和聚合获取数据的进一步阶段。 到目前为止，我所构建的逐步过程是:
在 localhost:9092 上运行 Kafka 实例
./bin/kafka-server-start.sh ./config/server.properties使用 docker 运行 beam-flink 作业服务器
docker run --net=host apache/beam_flink1.10_job_server:latest运行 beam-kafka 管道
import apache_beam as beam
from apache_beam.io.external.kafka import ReadFromKafka, WriteToKafka
from apache_beam.options.pipeline_options import PipelineOptions, StandardOptions
if __name__ == '__main__':
options = PipelineOptions([
"--job_endpoint=localhost:8099",
"--environment_type=LOOPBACK",
"--streaming",
"--environment_config={\"command\":\"/opt/apache/beam/boot\"}",
])
options = options.view_as(StandardOptions)
options.streaming = True
pipeline = beam.Pipeline(options=options)
result = (
pipeline
| "Read from kafka" >> ReadFromKafka(
consumer_config={
"bootstrap.servers": 'localhost:9092',
},
topics=['mytopic'],
expansion_service='localhost:8097',
)
| beam.Map(print)
)
pipeline.run()
- 使用kafka-producer.sh发布新消息
./bin/kafka-console-producer.sh --broker-list localhost:9092 --topic mytopic
>tryme
发布此试用消息后，Beam 管道感知到该消息但崩溃并给出此错误:
RuntimeError: org.apache.beam.sdk.util.UserCodeException: org.apache.beam.sdk.coders.CoderException: cannot encode a null byte[]
at org.apache.beam.sdk.util.UserCodeException.wrap(UserCodeException.java:36)
at org.apache.beam.fn.harness.FnApiDoFnRunner.outputTo(FnApiDoFnRunner.java:1014)
at org.apache.beam.fn.harness.FnApiDoFnRunner.access$1500(FnApiDoFnRunner.java:132)
at org.apache.beam.fn.harness.FnApiDoFnRunner$ProcessBundleContext.outputWithTimestamp(FnApiDoFnRunner.java:1483)
at org.apache.beam.fn.harness.FnApiDoFnRunner$ProcessBundleContext.output(FnApiDoFnRunner.java:1478)
at org.apache.beam.sdk.io.kafka.KafkaIO$TypedWithoutMetadata$1.processElement(KafkaIO.java:1042)
at org.apache.beam.sdk.io.kafka.KafkaIO$TypedWithoutMetadata$1$DoFnInvoker.invokeProcessElement(Unknown Source)
at org.apache.beam.fn.harness.FnApiDoFnRunner.processElementForParDo(FnApiDoFnRunner.java:740)
at org.apache.beam.fn.harness.FnApiDoFnRunner.access$700(FnApiDoFnRunner.java:132)
at org.apache.beam.fn.harness.FnApiDoFnRunner$Factory.lambda$createRunnerForPTransform$1(FnApiDoFnRunner.java:203)
at org.apache.beam.fn.harness.data.PCollectionConsumerRegistry$MetricTrackingFnDataReceiver.accept(PCollectionConsumerRegistry.java:216)
at org.apache.beam.fn.harness.data.PCollectionConsumerRegistry$MetricTrackingFnDataReceiver.accept(PCollectionConsumerRegistry.java:179)
at org.apache.beam.fn.harness.FnApiDoFnRunner.outputTo(FnApiDoFnRunner.java:1011)
at org.apache.beam.fn.harness.FnApiDoFnRunner.access$1500(FnApiDoFnRunner.java:132)
at org.apache.beam.fn.harness.FnApiDoFnRunner$ProcessBundleContext.outputWithTimestamp(FnApiDoFnRunner.java:1483)
at org.apache.beam.fn.harness.FnApiDoFnRunner$ProcessBundleContext.output(FnApiDoFnRunner.java:1478)
at org.apache.beam.sdk.values.ValueWithRecordId$StripIdsDoFn.processElement(ValueWithRecordId.java:138)
at org.apache.beam.sdk.values.ValueWithRecordId$StripIdsDoFn$DoFnInvoker.invokeProcessElement(Unknown Source)
at org.apache.beam.fn.harness.FnApiDoFnRunner.processElementForParDo(FnApiDoFnRunner.java:740)
at org.apache.beam.fn.harness.FnApiDoFnRunner.access$700(FnApiDoFnRunner.java:132)
at org.apache.beam.fn.harness.FnApiDoFnRunner$Factory.lambda$createRunnerForPTransform$1(FnApiDoFnRunner.java:203)
at org.apache.beam.fn.harness.data.PCollectionConsumerRegistry$MetricTrackingFnDataReceiver.accept(PCollectionConsumerRegistry.java:216)
at org.apache.beam.fn.harness.data.PCollectionConsumerRegistry$MetricTrackingFnDataReceiver.accept(PCollectionConsumerRegistry.java:179)
at org.apache.beam.fn.harness.FnApiDoFnRunner.outputTo(FnApiDoFnRunner.java:1011)
at org.apache.beam.fn.harness.FnApiDoFnRunner.access$1500(FnApiDoFnRunner.java:132)
at org.apache.beam.fn.harness.FnApiDoFnRunner$ProcessBundleContext.outputWithTimestamp(FnApiDoFnRunner.java:1483)
at org.apache.beam.sdk.transforms.DoFnOutputReceivers$WindowedContextOutputReceiver.outputWithTimestamp(DoFnOutputReceivers.java:84)
at org.apache.beam.sdk.io.Read$UnboundedSourceAsSDFWrapperFn.processElement(Read.java:516)
at org.apache.beam.sdk.io.Read$UnboundedSourceAsSDFWrapperFn$DoFnInvoker.invokeProcessElement(Unknown Source)
at org.apache.beam.fn.harness.FnApiDoFnRunner.processElementForElementAndRestriction(FnApiDoFnRunner.java:838)
at org.apache.beam.fn.harness.FnApiDoFnRunner.processElementForSizedElementAndRestriction(FnApiDoFnRunner.java:808)
at org.apache.beam.fn.harness.FnApiDoFnRunner.access$200(FnApiDoFnRunner.java:132)
at org.apache.beam.fn.harness.FnApiDoFnRunner$Factory$2.accept(FnApiDoFnRunner.java:226)
at org.apache.beam.fn.harness.FnApiDoFnRunner$Factory$2.accept(FnApiDoFnRunner.java:223)
at org.apache.beam.fn.harness.data.PCollectionConsumerRegistry$MetricTrackingFnDataReceiver.accept(PCollectionConsumerRegistry.java:216)
at org.apache.beam.fn.harness.data.PCollectionConsumerRegistry$MetricTrackingFnDataReceiver.accept(PCollectionConsumerRegistry.java:179)
at org.apache.beam.fn.harness.BeamFnDataReadRunner.forwardElementToConsumer(BeamFnDataReadRunner.java:204)
at org.apache.beam.fn.harness.data.QueueingBeamFnDataClient.drainAndBlock(QueueingBeamFnDataClient.java:106)
at org.apache.beam.fn.harness.control.ProcessBundleHandler.processBundle(ProcessBundleHandler.java:295)
at org.apache.beam.fn.harness.control.BeamFnControlClient.delegateOnInstructionRequestType(BeamFnControlClient.java:173)
at org.apache.beam.fn.harness.control.BeamFnControlClient.lambda$processInstructionRequests$0(BeamFnControlClient.java:157)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
Caused by: org.apache.beam.sdk.coders.CoderException: cannot encode a null byte[]
at org.apache.beam.sdk.coders.ByteArrayCoder.encode(ByteArrayCoder.java:63)
at org.apache.beam.sdk.coders.ByteArrayCoder.encode(ByteArrayCoder.java:56)
at org.apache.beam.sdk.coders.ByteArrayCoder.encode(ByteArrayCoder.java:41)
at org.apache.beam.sdk.coders.KvCoder.encode(KvCoder.java:70)
at org.apache.beam.sdk.coders.KvCoder.encode(KvCoder.java:36)
at org.apache.beam.sdk.util.WindowedValue$FullWindowedValueCoder.encode(WindowedValue.java:590)
at org.apache.beam.sdk.util.WindowedValue$FullWindowedValueCoder.encode(WindowedValue.java:581)
at org.apache.beam.sdk.util.WindowedValue$FullWindowedValueCoder.encode(WindowedValue.java:541)
at org.apache.beam.sdk.fn.data.BeamFnDataSizeBasedBufferingOutboundObserver.accept(BeamFnDataSizeBasedBufferingOutboundObserver.java:109)
at org.apache.beam.fn.harness.BeamFnDataWriteRunner.consume(BeamFnDataWriteRunner.java:155)
at org.apache.beam.fn.harness.data.PCollectionConsumerRegistry$MetricTrackingFnDataReceiver.accept(PCollectionConsumerRegistry.java:216)
at org.apache.beam.fn.harness.data.PCollectionConsumerRegistry$MetricTrackingFnDataReceiver.accept(PCollectionConsumerRegistry.java:179)
最佳答案
如果您还没有解决它，那么您正在发布一 strip 有空键值的消息，这会导致 Kafka 抛出异常并导致您的作业失败。
您可以使用 kafka 命令行工具将消息作为键值对发布，如下所示:
./bin/kafka-console-producer.sh \
--broker-list localhost:9092 \
--topic my-topic \
--property "parse.key=true" \
--property "key.separator=:"
>my_key:my_value
关于Python - Apache Beam - Flink 运行器设置 : ReadFromKafka returns error - RuntimeError: cannot encode a null byte[]，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/62899399/