我在AWS上的DC/OS(Mesos)群集上安装了Kafka。启用三个代理并创建了一个名为“topic1”的主题。为什么使用Client API for Java时,消费者在使用来自Kafka的DC/OS消息时挂起?
dcos kafka topic create topic1 --partitions 3 --replication 3
然后我写了一个Producer类来发送消息和一个Consumer类来接收它们。
public class Producer {
public static void sendMessage(String msg) throws InterruptedException, ExecutionException {
Map<String, Object> producerConfig = new HashMap<>();
System.out.println("setting Producerconfig.");
producerConfig.put("bootstrap.servers",
"172.16.20.207:9946,172.16.20.234:9125,172.16.20.36:9636");
ByteArraySerializer serializer = new ByteArraySerializer();
System.out.println("Creating KafkaProcuder");
KafkaProducer<byte[], byte[]> kafkaProducer = new KafkaProducer<>(producerConfig, serializer, serializer);
for (int i = 0; i < 100; i++) {
String msgstr = msg + i;
byte[] message = msgstr.getBytes();
ProducerRecord<byte[], byte[]> record = new ProducerRecord<>("topic1", message);
System.out.println("Sent:" + msgstr);
kafkaProducer.send(record);
}
kafkaProducer.close();
}
public static void main(String[] args) throws InterruptedException, ExecutionException {
sendMessage("Kafka test message 2/27 3:32");
}
}
public class Consumer {
public static String getMessage() {
Map<String, Object> consumerConfig = new HashMap<>();
consumerConfig.put("bootstrap.servers",
"172.16.20.207:9946,172.16.20.234:9125,172.16.20.36:9636");
consumerConfig.put("group.id", "dj-group");
consumerConfig.put("enable.auto.commit", "true");
consumerConfig.put("auto.offset.reset", "earliest");
ByteArrayDeserializer deserializer = new ByteArrayDeserializer();
KafkaConsumer<byte[], byte[]> kafkaConsumer = new KafkaConsumer<>(consumerConfig, deserializer, deserializer);
kafkaConsumer.subscribe(Arrays.asList("topic1"));
while (true) {
ConsumerRecords<byte[], byte[]> records = kafkaConsumer.poll(100);
System.out.println(records.count() + " of records received.");
for (ConsumerRecord<byte[], byte[]> record : records) {
System.out.println(Arrays.toString(record.value()));
}
}
}
public static void main(String[] args) {
getMessage();
}
}
首先,我在集群上运行Producer
将消息发送到topic1
。但是,当我运行Consumer
时,它无法接收任何内容,只是挂起。
Producer
工作,因为我可以通过运行与卡夫卡附带的shell脚本来获取所有的信息安装
./bin/kafka-console-consumer.sh --zookeeper master.mesos:2181/dcos-service-kafka --topic topic1 --from-beginning
但我为什么可以接收不Consumer
?这post建议与旧的偏移量group.id可能是一个可能的原因。我只在消费者而不是生产者中创建group.id。我如何配置这个组的偏移量?
为了确保group.id不是问题,请使用'kafkaConsumer.seekToBeginning()' –
@ MatthiasJ.Sax我应该删除'consumerConfig.put(“auto.offset.reset”,“earliest”); “那么?在订阅后,我应该在哪里添加此行?添加后仍然没有得到任何东西。 – ddd
尝试调用轮询时使用更长的超时,并且在服务器/客户端的日志中是否存在任何异常? – amethystic