org.apache.kafka.common.errors.CoordinatorLoadInProgressException: 协调器正在加载，无法处理请求

解决方案

1. Wait for coordinator to finish loading; check broker logs for 'Finished loading offsets from __consumer_offsets'.
   Command to monitor:
   kafka-consumer-groups --bootstrap-server localhost:9092 --group my-group --describe --members --verbose
   If loading takes too long, increase offsets.load.buffer.size in broker config:
   echo "offsets.load.buffer.size=10485760" >> config/server.properties
   kafka-server-start.sh config/server.properties

2. Use exponential backoff in consumer retry logic to avoid overwhelming the coordinator.
   Code example:
   int retries = 0;
   while (retries < 5) {
     try {
       consumer.poll(Duration.ofMillis(1000));
       break;
     } catch (CoordinatorLoadInProgressException e) {
       Thread.sleep((long) Math.pow(2, retries) * 1000);
       retries++;
     }
   }