Chesnay Schepler created FLINK-25979:
----------------------------------------
Summary: Suspicious Classloading error during close of
KafkaEnumerator
Key: FLINK-25979
URL: https://issues.apache.org/jira/browse/FLINK-25979
Project: Flink
Issue Type: Bug
Components: Connectors / Common, Connectors / Kafka
Affects Versions: 1.14.2
Reporter: Chesnay Schepler
A user reported kafka logging a warning when the KafkaEnumerator was being
closed.
{code}
2022-02-04 15:16:30,801 WARN org.apache.kafka.common.utils.Utils
[] - Failed to close KafkaClient with type
org.apache.kafka.clients.NetworkClient
java.lang.NoClassDefFoundError:
org/apache/kafka/common/network/Selector$CloseMode
at org.apache.kafka.common.network.Selector.close(Selector.java:806)
~[blob_p-d9d83f46e9376826081af75cb6693b745018f7ca-988b5e01be784cebb00104c3aa45094b:?]
at org.apache.kafka.common.network.Selector.close(Selector.java:365)
~[blob_p-d9d83f46e9376826081af75cb6693b745018f7ca-988b5e01be784cebb00104c3aa45094b:?]
at org.apache.kafka.clients.NetworkClient.close(NetworkClient.java:639)
~[blob_p-d9d83f46e9376826081af75cb6693b745018f7ca-988b5e01be784cebb00104c3aa45094b:?]
at org.apache.kafka.common.utils.Utils.closeQuietly(Utils.java:834)
[blob_p-d9d83f46e9376826081af75cb6693b745018f7ca-988b5e01be784cebb00104c3aa45094b:?]
at
org.apache.kafka.clients.admin.KafkaAdminClient$AdminClientRunnable.run(KafkaAdminClient.java:1219)
[blob_p-d9d83f46e9376826081af75cb6693b745018f7ca-988b5e01be784cebb00104c3aa45094b:?]
at java.lang.Thread.run(Thread.java:829) [?:?]
Caused by: java.lang.ClassNotFoundException:
org.apache.kafka.common.network.Selector$CloseMode
at java.net.URLClassLoader.findClass(URLClassLoader.java:476) ~[?:?]
at java.lang.ClassLoader.loadClass(ClassLoader.java:589) ~[?:?]
at
org.apache.flink.util.FlinkUserCodeClassLoader.loadClassWithoutExceptionHandling(FlinkUserCodeClassLoader.java:64)
~[flink-dist_2.12-1.14.2.jar:1.14.2]
at
org.apache.flink.util.ChildFirstClassLoader.loadClassWithoutExceptionHandling(ChildFirstClassLoader.java:74)
~[flink-dist_2.12-1.14.2.jar:1.14.2]
at
org.apache.flink.util.FlinkUserCodeClassLoader.loadClass(FlinkUserCodeClassLoader.java:48)
~[flink-dist_2.12-1.14.2.jar:1.14.2]
at java.lang.ClassLoader.loadClass(ClassLoader.java:522) ~[?:?]
... 6 more
2022-02-04 15:16:30,802 INFO
org.apache.flink.runtime.source.coordinator.SourceCoordinator [] - Source
coordinator for source Source: Kafka Source -> Sink: Print to Std. Out closed.
{code}
{code}
KafkaSource<String> source = KafkaSource
.<String>builder()
.setBootstrapServers(brokers)
.setGroupId(groupId)
.setTopics(kafkaInputTopic)
.setValueOnlyDeserializer(new SimpleStringSchema())
//.setDeserializer(KafkaRecordDeserializationSchema.valueOnly(StringDeSerializer.class))
.setStartingOffsets(OffsetsInitializer.earliest())
.setBounded(OffsetsInitializer.latest())
.build();
//withIdleness.duration()
//env.fromSource(source, WatermarkStrategy.forMonotonousTimestamps(), "Kafka
Source");
DataStream<String> ds = env.fromSource(source,
WatermarkStrategy.forMonotonousTimestamps(), "Kafka Source");
{code}
This error is overall a bit weird; I don't think I've ever seen a class being
unable to load one of it's inner classes. intuitively I would think this is
caused by the classloader being closed prematurely.
ds.print();
{code}
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