props.put("group.id", "test-group");有什么用
时间: 2023-12-11 18:04:28 浏览: 13
这是 Kafka 中 Consumer 配置属性之一,用于指定 Consumer 所属的消费者组。Kafka 中的消息被分配给消费者组中的每个 Consumer 进程进行消费,同一组中的 Consumer 进程共同消费订阅的主题中的消息。当一个 Consumer 进程加入到一个消费者组时,它会从该组所订阅的主题中读取数据,并且该组内的其他 Consumer 进程不再读取该消息。通过将多个 Consumer 进程组成一个消费者组,可以实现消息的负载均衡和高可用性。因此,设置正确的消费者组可以有效地提高消费者的效率和可靠性。
相关问题
clientId=consumer-SYNC-GROUP-8如何配置
clientId是Kafka consumer group的标识符,用于区分不同的consumer group。可以在创建KafkaConsumer实例时通过传入一个Properties对象来设置clientId属性。
例如,可以使用以下代码创建一个KafkaConsumer实例,并设置其clientId属性:
```java
Properties props = new Properties();
props.put("bootstrap.servers", "localhost:9092");
props.put("group.id", "test-group");
props.put("client.id", "consumer-1");
props.put("key.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
props.put("value.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
KafkaConsumer<String, String> consumer = new KafkaConsumer<>(props);
```
在上面的代码中,我们将client.id属性设置为“consumer-1”,以便将consumer与特定的client标识符关联起来。如果要使用不同的clientId,只需将其更改为所需的值即可。
Kafka消费者订阅分区 在命令行启动Kafka后,手动创建’assgin_topic’主题,分区数量为2,执行命令如下: .\bin\windows\kafka-topics.bat --create --zookeeper localhost:2181 --replication-factor 1 --partitions 2 --topic assign_topic 1. 根据上面给出的主题,完成如下操作: (1)编写生产者程序,以通用唯一标识符UUID作为消息,发送给主题assign_topic; (2)编写消费者程序1,订阅主题的分区0,只消费分区0数据; (3)编写消费者程序2,订阅主题的分区1,只消费分区1数据;
以下是相应的代码:
生产者程序:
```java
import org.apache.kafka.clients.producer.*;
import java.util.Properties;
import java.util.UUID;
public class ProducerDemo {
public static void main(String[] args) {
String topicName = "assign_topic";
Properties props = new Properties();
props.put("bootstrap.servers", "localhost:9092");
props.put("acks", "all");
props.put("retries", 0);
props.put("batch.size", 16384);
props.put("linger.ms", 1);
props.put("buffer.memory", 33554432);
props.put("key.serializer", "org.apache.kafka.common.serialization.StringSerializer");
props.put("value.serializer", "org.apache.kafka.common.serialization.StringSerializer");
Producer<String, String> producer = new KafkaProducer<>(props);
for (int i = 0; i < 10; i++) {
String uuid = UUID.randomUUID().toString();
producer.send(new ProducerRecord<>(topicName, uuid));
}
producer.close();
}
}
```
消费者程序1:
```java
import org.apache.kafka.clients.consumer.*;
import org.apache.kafka.common.TopicPartition;
import java.util.Collections;
import java.util.Properties;
public class ConsumerDemo1 {
public static void main(String[] args) {
String topicName = "assign_topic";
Properties props = new Properties();
props.put("bootstrap.servers", "localhost:9092");
props.put("group.id", "test-group");
props.put("enable.auto.commit", "true");
props.put("auto.commit.interval.ms", "1000");
props.put("key.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
props.put("value.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
KafkaConsumer<String, String> consumer = new KafkaConsumer<>(props);
TopicPartition partition0 = new TopicPartition(topicName, 0);
consumer.assign(Collections.singletonList(partition0));
while (true) {
ConsumerRecords<String, String> records = consumer.poll(100);
for (ConsumerRecord<String, String> record : records) {
System.out.printf("offset = %d, key = %s, value = %s%n", record.offset(), record.key(), record.value());
}
}
}
}
```
消费者程序2:
```java
import org.apache.kafka.clients.consumer.*;
import org.apache.kafka.common.TopicPartition;
import java.util.Collections;
import java.util.Properties;
public class ConsumerDemo2 {
public static void main(String[] args) {
String topicName = "assign_topic";
Properties props = new Properties();
props.put("bootstrap.servers", "localhost:9092");
props.put("group.id", "test-group");
props.put("enable.auto.commit", "true");
props.put("auto.commit.interval.ms", "1000");
props.put("key.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
props.put("value.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
KafkaConsumer<String, String> consumer = new KafkaConsumer<>(props);
TopicPartition partition1 = new TopicPartition(topicName, 1);
consumer.assign(Collections.singletonList(partition1));
while (true) {
ConsumerRecords<String, String> records = consumer.poll(100);
for (ConsumerRecord<String, String> record : records) {
System.out.printf("offset = %d, key = %s, value = %s%n", record.offset(), record.key(), record.value());
}
}
}
}
```
生产者程序通过生成UUID作为消息,发送给主题"assign_topic"。消费者程序1订阅了主题"assign_topic"的分区0,只消费分区0数据;消费者程序2订阅了主题"assign_topic"的分区1,只消费分区1数据。