Spring cloud kafka stream application terminates on exception - spring-boot

Question

I have simple spring cloud kafka stream application. The application terminates each time there is an exception and I'm unable to overwrite this behaviour. The desired outcome is incremental backoff when there are certain types of exceptions or to continue on other type of exceptions. I use springCloudVersion - Hoxton.SR3 and spring boot: 2.2.6.RELEASE
application.yaml
spring:
cloud:
stream:
binders.process-in-0:
destination: test
kafka:
streams:
binder:
deserializationExceptionHandler: logAndContinue
configuration:
default.key.serde: org.apache.kafka.common.serialization.Serdes$StringSerde
default.value.serde: org.apache.kafka.common.serialization.Serdes$StringSerde
Beans
#Bean
public java.util.function.Consumer<KStream<String, String>> process() {
return input -> input.process(() -> new EventProcessor());
}
#Bean
public StreamsBuilderFactoryBeanCustomizer customizer() {
return fb -> {
fb.getStreamsConfiguration().put(StreamsConfig.DEFAULT_PRODUCTION_EXCEPTION_HANDLER_CLASS_CONFIG,
ContinueOnErrorHandler.class);
};
}
EventProcessor
public class EventProcessor implements Processor<String, String>, ProcessorSupplier<String, String> {
private ProcessorContext context;
#Override
public void init(ProcessorContext context) {
this.context = context;
}
#Override
public void process(String key, String value) {
throw new RuntimeException("Some exception");
}
#Override
public void close() {
}
#Override
public Processor<String, String> get() {
return this;
}
}
ContinueOnErrorHandler
public class ContinueOnErrorHandler implements ProductionExceptionHandler {
#Override
public ProductionExceptionHandlerResponse handle(ProducerRecord<byte[], byte[]> record, Exception exception) {
return ProductionExceptionHandlerResponse.CONTINUE;
}
#Override
public void configure(Map<String, ?> configs) {
//ignore
}
}

Answer 1

The custom processor you are using from the consumer is throwing a RuntimeException in the process method. It is not caught by anything. When that exception is thrown, the application simply exits.
The production exception handler that you are using does not have any effect here since you are not producing anything here. Consumer does not produce anything. If you have a use case of producing something, you should switch to java.util.funciton.Function instead.
In order to fix the issue here, as you are processing the record in the custom processor (EventProcessor), if you get an exception, you should catch it and take appropriate actions. For e.g, here is a template:
#Override
public void init(ProcessorContext context) {
this.context = context;
}
#Override
public void process(String key, String value) {
try {
// start processing
// exception thrown
}
catch (Exception e){
// Take the appropriate action
}
}
This way, the application won't be terminated when the exception is thrown in the processor.