Vadym Chekrii created CAMEL-10115:
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Summary: Kafka consumer is being left running if no message were
received after shutdown start
Key: CAMEL-10115
URL: https://issues.apache.org/jira/browse/CAMEL-10115
Project: Camel
Issue Type: Bug
Components: camel-kafka
Affects Versions: 2.17.1
Environment: Spring Boot 1.4.0.M3 with Tomcat
Java 8
Camel 2.17.1
Reporter: Vadym Chekrii
After triggering {{CamelContext#close()}} method the execution will reach
{{org.apache.camel.component.kafka.KafkaConsumer#doStop}} where the shutdown of
the executor instance will be triggered and where in it's turn the interruption
of the submitted to the executor threads should happen (by reaching the native
implementation of Thread#interrupt())
According to
https://docs.oracle.com/javase/8/docs/api/java/lang/Thread.html#interrupt--
interrupt method will only set a corresponding status to the thread, but will
not terminate it.
Problem is in the line {{KafkaConsumer.java:108}}
{{ConsumerRecords<Object, Object> records = consumer.poll(Long.MAX_VALUE);}}
In the Kafka implementation of the poll method this will lead to almost
infinite `while` loop which is not checking the thread status and this loop
will exit only in case of receiving a message from a broker. Only after
exciting the loop the interupted status of the thread will be discovered and
the thread will be terminated.
This leads to a couple of problems:
1. The KafkaConsumers remain alive until receiving at least one more message
from the broker.
2. As the CamelContext at this point of time is most likely already shut down,
the received message is not going to be processed, but will be acknwoledged to
the broker. So effectively the message gets lost.
A potential fix would be to either make poll timeout reasonably small, or make
it configurable.
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