Kafka只流一次送货

Question

我的目标是从主题A消费，做一些处理和生产到主题B，作为单个原子动作。要做到这一点，我有两种选择：

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我已成功验证选项#1。所谓成功，是指如果我的处理失败（抛出IllegalArgumentException），来自主题A的已消费消息将继续被KafKalistener消费。这是我所期望的，因为没有提交偏移量，而使用了DefaultAfterRollbackProcessor。

我希望看到相同的行为，如果我使用一个流来从主题a消费、处理并发送到主题B（选项2），而不是KafkaListener。但是，即使在我处理IllegalArgumentException时抛出了一个消息，该消息也只被流使用一次。这是预期的行为吗？

在流的情况下,我只有以下配置：

@Configuration
@EnableKafkaStreams
public class KafkaStreamsConfiguration {

    @Bean(name = KafkaStreamsDefaultConfiguration.DEFAULT_STREAMS_CONFIG_BEAN_NAME)
    public StreamsConfig  kStreamsConfigs() {
        Map<String, Object> props = new HashMap<>();
        props.put(StreamsConfig.BOOTSTRAP_SERVERS_CONFIG, "http://localhost:9092");
        props.put(StreamsConfig.APPLICATION_ID_CONFIG, "calculate-tax-sender-invoice-stream");        
        props.put(AbstractKafkaAvroSerDeConfig.SCHEMA_REGISTRY_URL_CONFIG, "http://localhost:8082");
        // this should be enough to enable transactions
        props.put(StreamsConfig.PROCESSING_GUARANTEE_CONFIG, StreamsConfig.EXACTLY_ONCE);
        return new StreamsConfig(props);
    }
}

//required to create and start a new KafkaStreams, as when an exception is thrown the stream dies
// see here: https://docs.spring.io/spring-kafka/reference/html/_reference.html#after-rollback
@Bean(name = KafkaStreamsDefaultConfiguration.DEFAULT_STREAMS_BUILDER_BEAN_NAME)
public StreamsBuilderFactoryBean myKStreamBuilder(StreamsConfig streamsConfig) {
    StreamsBuilderFactoryBean streamsBuilderFactoryBean = new StreamsBuilderFactoryBean(streamsConfig);
    streamsBuilderFactoryBean.setUncaughtExceptionHandler(new Thread.UncaughtExceptionHandler() {
        @Override
        public void uncaughtException(Thread t, Throwable e) {
            log.debug("StopStartStreamsUncaughtExceptionHandler caught exception {}, stopping StreamsThread ..", e);
            streamsBuilderFactoryBean.stop();
            log.debug("creating and starting a new StreamsThread ..");
            streamsBuilderFactoryBean.start();
        }
    });
    return streamsBuilderFactoryBean;
}

@Autowired
public SpecificAvroSerde<InvoiceEvents> eventSerde;

@Autowired
private TaxService taxService;

@Bean
public KStream<String, InvoiceEvents> kStream(StreamsBuilder builder) {

    KStream<String, InvoiceEvents> kStream = builder.stream("A",
            Consumed.with(Serdes.String(), eventSerde));

      kStream
        .mapValues(v -> 
            {
                // get tax from possibly remote service
                // an IllegalArgumentException("Tax calculation failed") is thrown by getTaxForInvoice()
                int tax = taxService.getTaxForInvoice(v);
                // create a TaxCalculated event
                InvoiceEvents taxCalculatedEvent = InvoiceEvents.newBuilder().setType(InvoiceEvent.TaxCalculated).setTax(tax).build();
                log.debug("Generating TaxCalculated event: {}", taxCalculatedEvent);
                return taxCalculatedEvent;
            })
        .to("B", Produced.with(Serdes.String(), eventSerde));

    return kStream;
}

我的单元测试：

@Test
public void calculateTaxForInvoiceTaxCalculationFailed() throws Exception {
    log.debug("running test calculateTaxForInvoiceTaxCalculationFailed..");
    Mockito.when(taxService.getTaxForInvoice(any(InvoiceEvents.class)))
                        .thenThrow(new IllegalArgumentException("Tax calculation failed"));

    InvoiceEvents invoiceCreatedEvent = createInvoiceCreatedEvent();
    List<KeyValue<String, InvoiceEvents>> inputEvents = Arrays.asList(
            new KeyValue<String, InvoiceEvents>("A", invoiceCreatedEvent));

     Properties producerConfig = new Properties();
     producerConfig.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, "http://localhost:9092");
     producerConfig.put(ProducerConfig.ACKS_CONFIG, "all");
     producerConfig.put(ProducerConfig.RETRIES_CONFIG, 1);
     producerConfig.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());
     producerConfig.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, KafkaAvroSerializer.class.getName());
     producerConfig.put(AbstractKafkaAvroSerDeConfig.SCHEMA_REGISTRY_URL_CONFIG, "http://localhost:8082");
     producerConfig.put(ProducerConfig.CLIENT_ID_CONFIG, "unit-test-producer");

    // produce with key
    IntegrationTestUtils.produceKeyValuesSynchronously("A", inputEvents, producerConfig);

    // wait for 30 seconds - I should observe re-consumptions of invoiceCreatedEvent, but I do not
    Thread.sleep(30000);
// ...
}

更新：在我的单元测试中，我发送了50个invoiceEvents(orderId=1,...,50)，我处理了它们并将它们发送到目标主题。

在我的日志中，我看到的行为如下：

invoiceEvent.orderId = 43 → consumed and successfully processed
invoiceEvent.orderId = 44 → consumed and IlleagalArgumentException thrown
..new stream starts..
invoiceEvent.orderId = 44 → consumed and successfully processed
invoiceEvent.orderId = 45 → consumed and successfully processed
invoiceEvent.orderId = 46 → consumed and successfully processed
invoiceEvent.orderId = 47 → consumed and successfully processed
invoiceEvent.orderId = 48 → consumed and successfully processed
invoiceEvent.orderId = 49 → consumed and successfully processed
invoiceEvent.orderId = 50 → consumed and IlleagalArgumentException thrown
...
[29-0_0-producer] task [0_0] Error sending record (key A value {"type": ..., "payload": {**"id": "46"**, ... }}} timestamp 1529583666036) to topic invoice-with-tax.t due to {}; No more records will be sent and no more offsets will be recorded for this task.
..new stream starts..
invoiceEvent.**orderId = 46** → consumed and successfully processed
invoiceEvent.orderId = 47 → consumed and successfully processed
invoiceEvent.orderId = 48 → consumed and successfully processed
invoiceEvent.orderId = 49 → consumed and successfully processed
invoiceEvent.orderId = 50 → consumed and successfully processed

Answer 1

使选项2（流事务）工作的要点是：

>

分配一个Thread.UnaughtExceptionHandler（）以便在出现任何未捕获的异常时启动一个新的StreamThread（默认情况下StreamThread会死亡-请参阅下面的代码段）。如果生产到Kafka代理失败，甚至会发生这种情况，它不必与流中的业务逻辑代码相关。

请考虑设置一个策略来处理消息的去序列化（当您使用消息时）。检查DEFAULT_DESERIALIZATION_EXCEPTION_HANDLER_CLASS_CONFIG(javadoc)。例如，您应该忽略并使用下一条消息还是停止使用相关Kafka分区的消息。

对于流，即使设置了max_poll_records_config=1（每个轮询/批处理一个记录），仍然不会提交每个消息所消耗的偏移量和生成的消息。这种情况会导致问题中描述的情况（请参见“Why after the nind failure,it re-consumes from InvoiceEvent.OrderId=46？”）。

Kafka事务还不能在Windows上工作。该修复程序将在Kafka 1.1.1中提供(https://issues.apache.org/jira/browse/html" target="_blank">kafka-6052)。

请考虑检查如何处理序列化异常（或生产过程中的一般异常）（此处和此处）

@Configuration
@EnableKafkaStreams
public class KafkaStreamsConfiguration {
    @Bean(name = KafkaStreamsDefaultConfiguration.DEFAULT_STREAMS_CONFIG_BEAN_NAME)
    public StreamsConfig  kStreamsConfigs() {
        Map<String, Object> props = new HashMap<>();
        props.put(StreamsConfig.BOOTSTRAP_SERVERS_CONFIG, "http://localhost:9092");
        props.put(StreamsConfig.APPLICATION_ID_CONFIG, "blabla");
        props.put(AbstractKafkaAvroSerDeConfig.SCHEMA_REGISTRY_URL_CONFIG, "http://localhost:8082");
        // this should be enough to enable transactions
        props.put(StreamsConfig.PROCESSING_GUARANTEE_CONFIG, StreamsConfig.EXACTLY_ONCE);
        return new StreamsConfig(props);
    }
}

@Bean(name = KafkaStreamsDefaultConfiguration.DEFAULT_STREAMS_BUILDER_BEAN_NAME)
public StreamsBuilderFactoryBean myKStreamBuilder(StreamsConfig streamsConfig) 
{
    StreamsBuilderFactoryBean streamsBuilderFactoryBean = new StreamsBuilderFactoryBean(streamsConfig);
    streamsBuilderFactoryBean.setUncaughtExceptionHandler(new Thread.UncaughtExceptionHandler() {
        @Override
        public void uncaughtException(Thread t, Throwable e) {
            log.debug("StopStartStreamsUncaughtExceptionHandler caught exception {}, stopping StreamsThread ..", e);
            streamsBuilderFactoryBean.stop();
            log.debug("creating and starting a new StreamsThread ..");
            streamsBuilderFactoryBean.start();
        }
    });
    return streamsBuilderFactoryBean;
}