Ayush Sharma created BEAM-10484:
-----------------------------------
Summary: Python - Apache Beam - Flink runner setup: ReadFromKafka
returns error - RuntimeError: cannot encode a null byte[]
Key: BEAM-10484
URL: https://issues.apache.org/jira/browse/BEAM-10484
Project: Beam
Issue Type: Bug
Components: beam-model, cross-language, io-py-kafka, runner-flink
Reporter: Ayush Sharma
I am trying to build a streaming beam pipeline in python which should capture
messages from kafka and then execute further stages of data fetching from other
sources and aggregation. The step-by-step process of what I have built till now
is:
# Running Kafka instance on localhost:9092
{code:java}
./bin/kafka-server-start.sh ./config/server.properties
{code}
{{}}
# Run beam-flink job server using docker{{}}
{code:java}
{code}
{{docker run --net=host apache/beam_flink1.10_job_server:latest}}
# Run beam-kafka pipeline
{code:java}
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(){code}
# Publish new message using kafka-producer.sh
{code:java}
./bin/kafka-console-producer.sh --broker-list localhost:9092 --topic mytopic
>tryme{code}
After publishing this trial message, the beam pipeline perceives the message
but crashes giving this error:
{code:java}
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)
{code}
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