[KAFKA-12914] StreamSourceNode.toString() throws with StreamsBuilder.stream(Pattern) ctor

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 2.8.0
• Fix Version/s: 2.8.1, 3.0.0
• Component/s: streams
• Assignee: Matthias J. Sax
• Reporter: Will Bartlett
• Created: 08/Jun/21 15:44
• Updated: 15/Jun/21 08:54
• Resolved: 15/Jun/21 08:00

Description

Hi, 

I came across what looks like a bug.

Repro

import org.apache.kafka.common.serialization.Serdes
import org.apache.kafka.streams.KafkaStreams
import org.apache.kafka.streams.StreamsBuilder
import org.apache.kafka.streams.kstream.Consumed
import java.util.*
import java.util.regex.Pattern

fun main() {
    val builder = StreamsBuilder()
    builder.stream(Pattern.compile("foo"), Consumed.with(Serdes.Long(), Serdes.Long()))
    val streams = KafkaStreams(builder.build(), Properties())
    streams.start()
}

SLF4J: Failed toString() invocation on an object of type [java.util.LinkedHashSet]
Reported exception:
java.lang.NullPointerException
	at java.base/java.util.Collections$UnmodifiableCollection.<init>(Collections.java:1030)
	at java.base/java.util.Collections$UnmodifiableSet.<init>(Collections.java:1132)
	at java.base/java.util.Collections.unmodifiableSet(Collections.java:1122)
	at org.apache.kafka.streams.kstream.internals.graph.SourceGraphNode.topicNames(SourceGraphNode.java:55)
	at org.apache.kafka.streams.kstream.internals.graph.StreamSourceNode.toString(StreamSourceNode.java:65)
	at java.base/java.lang.String.valueOf(String.java:3352)
	at java.base/java.lang.StringBuilder.append(StringBuilder.java:166)
	at java.base/java.util.AbstractCollection.toString(AbstractCollection.java:457)
	at org.slf4j.helpers.MessageFormatter.safeObjectAppend(MessageFormatter.java:277)
	at org.slf4j.helpers.MessageFormatter.deeplyAppendParameter(MessageFormatter.java:249)
	at org.slf4j.helpers.MessageFormatter.arrayFormat(MessageFormatter.java:211)
	at org.slf4j.helpers.MessageFormatter.arrayFormat(MessageFormatter.java:161)
	at ch.qos.logback.classic.spi.LoggingEvent.getFormattedMessage(LoggingEvent.java:293)
	at ch.qos.logback.classic.spi.LoggingEvent.prepareForDeferredProcessing(LoggingEvent.java:206)
	at ch.qos.logback.core.OutputStreamAppender.subAppend(OutputStreamAppender.java:223)
	at ch.qos.logback.core.OutputStreamAppender.append(OutputStreamAppender.java:102)
	at ch.qos.logback.core.UnsynchronizedAppenderBase.doAppend(UnsynchronizedAppenderBase.java:84)
	at ch.qos.logback.core.spi.AppenderAttachableImpl.appendLoopOnAppenders(AppenderAttachableImpl.java:51)
	at ch.qos.logback.classic.Logger.appendLoopOnAppenders(Logger.java:270)
	at ch.qos.logback.classic.Logger.callAppenders(Logger.java:257)
	at ch.qos.logback.classic.Logger.buildLoggingEventAndAppend(Logger.java:421)
	at ch.qos.logback.classic.Logger.filterAndLog_2(Logger.java:414)
	at ch.qos.logback.classic.Logger.debug(Logger.java:490)
	at org.apache.kafka.streams.kstream.internals.InternalStreamsBuilder.buildAndOptimizeTopology(InternalStreamsBuilder.java:305)
	at org.apache.kafka.streams.StreamsBuilder.build(StreamsBuilder.java:624)
	at org.apache.kafka.streams.StreamsBuilder.build(StreamsBuilder.java:613)
	at ApplicationKt.main(Application.kt:11)
	at ApplicationKt.main(Application.kt)
SLF4J: Failed toString() invocation on an object of type [org.apache.kafka.streams.kstream.internals.graph.StreamSourceNode]
Reported exception:
java.lang.NullPointerException
	at java.base/java.util.Collections$UnmodifiableCollection.<init>(Collections.java:1030)
	at java.base/java.util.Collections$UnmodifiableSet.<init>(Collections.java:1132)
	at java.base/java.util.Collections.unmodifiableSet(Collections.java:1122)
	at org.apache.kafka.streams.kstream.internals.graph.SourceGraphNode.topicNames(SourceGraphNode.java:55)
	at org.apache.kafka.streams.kstream.internals.graph.StreamSourceNode.toString(StreamSourceNode.java:65)
	at org.slf4j.helpers.MessageFormatter.safeObjectAppend(MessageFormatter.java:277)
	at org.slf4j.helpers.MessageFormatter.deeplyAppendParameter(MessageFormatter.java:249)
	at org.slf4j.helpers.MessageFormatter.arrayFormat(MessageFormatter.java:211)
	at org.slf4j.helpers.MessageFormatter.arrayFormat(MessageFormatter.java:161)
	at ch.qos.logback.classic.spi.LoggingEvent.getFormattedMessage(LoggingEvent.java:293)
	at ch.qos.logback.classic.spi.LoggingEvent.prepareForDeferredProcessing(LoggingEvent.java:206)
	at ch.qos.logback.core.OutputStreamAppender.subAppend(OutputStreamAppender.java:223)
	at ch.qos.logback.core.OutputStreamAppender.append(OutputStreamAppender.java:102)
	at ch.qos.logback.core.UnsynchronizedAppenderBase.doAppend(UnsynchronizedAppenderBase.java:84)
	at ch.qos.logback.core.spi.AppenderAttachableImpl.appendLoopOnAppenders(AppenderAttachableImpl.java:51)
	at ch.qos.logback.classic.Logger.appendLoopOnAppenders(Logger.java:270)
	at ch.qos.logback.classic.Logger.callAppenders(Logger.java:257)
	at ch.qos.logback.classic.Logger.buildLoggingEventAndAppend(Logger.java:421)
	at ch.qos.logback.classic.Logger.filterAndLog_2(Logger.java:414)
	at ch.qos.logback.classic.Logger.debug(Logger.java:490)
	at org.apache.kafka.streams.kstream.internals.InternalStreamsBuilder.buildAndOptimizeTopology(InternalStreamsBuilder.java:305)
	at org.apache.kafka.streams.StreamsBuilder.build(StreamsBuilder.java:624)
	at org.apache.kafka.streams.StreamsBuilder.build(StreamsBuilder.java:613)
	at ApplicationKt.main(Application.kt:11)
	at ApplicationKt.main(Application.kt)

Kotlin but you get the idea.

Brief debug

StreamSourceNode.toString() calls topicNames():

https://github.com/apache/kafka/blob/1dadb6db0c6848a8a1d2eee1497f9b79b6e04e0e/streams/src/main/java/org/apache/kafka/streams/kstream/internals/graph/StreamSourceNode.java#L64-L70

Which will be null if constructed with a Pattern rather than a String:

https://github.com/apache/kafka/blob/1dadb6db0c6848a8a1d2eee1497f9b79b6e04e0e/streams/src/main/java/org/apache/kafka/streams/kstream/internals/graph/SourceGraphNode.java#L49

Which causes UnmodifiableCollection to throw.

 

Issue Links

• links to: GitHub Pull Request #10846