Kafka partition扩充并且需要迁移数据
 生产不用指定具体分区,会自动分配
 拉取也不用指定具体分区,会自动拉多个分区
可以同时拉取多个topic
kafka配置
 <dependency>
     <groupId>org.apache.kafka</groupId>
     <artifactId>kafka_2.12</artifactId>
     <version>2.3.0</version>
 </dependency>
 Properties proprops = new Properties();
 proprops.put(“bootstrap.servers”, “192.168.31.234:59092”);
 proprops.put(“acks”, “all”);
 proprops.put(“key.serializer”, “org.apache.kafka.common.serialization.StringSerializer”);
 proprops.put(“value.serializer”, “org.apache.kafka.common.serialization.StringSerializer”);
Producer<String, String> producer = new KafkaProducer<>(proprops);
 for (int i = 0; i < 9999; i++)
     producer.send(new ProducerRecord<String, String>(“my-topic3”, Integer.toString(i), Integer.toString(i)));
producer.close();
 Properties props = new Properties();
 props.put(“bootstrap.servers”, “192.168.31.234:59092”);
 props.put(“group.id”, “test6”);
 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”);
 //        props.put(“zookeeper.session.timeout.ms”, “40000”);
 //        props.put(“zookeeper.sync.time.ms”, “200”);
 //        props.put(“rebalance.max.retries”, “5”);
 //        props.put(“rebalance.backoff.ms”, “12000”);
 KafkaConsumer<String, String> consumer = new KafkaConsumer<>(props);
 //        consumer.subscribe(Arrays.asList(“my-topic2”));
 consumer.subscribe(Collections.singletonList(“my-topic3”));
while (true) {
     ConsumerRecords<String, String> records = consumer.poll(Duration.ofSeconds(5));
     System.out.printf(“2222222222222″+ records.toString());
     for (ConsumerRecord<String, String> record : records) {
         System.out.println(“llllllllllllllllll” + record);
         System.out.printf(“offset = %d, key = %s, value = %s%n”, record.offset(), record.key(), record.value());
     }
 }
eureka 快速刷新配置
eureka:
   server:
     #关闭自我保护
     enable-self-preservation: false
     #不读取只读的缓存服务清单,因为30秒刷新一次比较慢,读写高速缓存过期策略
     UseReadOnlyResponseCache: false
     #启用主动失效,并且每次主动失效检测间隔为3s
     eviction-interval-timer-in-ms: 3000
   instance:
     hostname: localhost
     #服务过期时间配置,超过这个时间没有接收到心跳EurekaServer就会将这个实例剔除
     #注意,EurekaServer一定要设置eureka.server.eviction-interval-timer-in-ms否则这个配置无效,这个配置一般为服务刷新时间配置的三倍
     #默认90s
     lease-expiration-duration-in-seconds: 15
     #服务刷新时间配置,每隔这个时间会主动心跳一次
     #默认30s
     lease-renewal-interval-in-seconds: 5
   client:
     #客户端:服务缓存清单也是默认30秒更新一次,可通过设置RegistryFetchIntervalSeconds来缩短,单位是秒
     registryFetchIntervalSeconds: 5
     registerWithEureka: false
     fetchRegistry: false
     serviceUrl:
       defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/

