我有 Kafka 主题“purchase2”，其中包含 2 个分区和 Kafka REST 代理供消费者使用（来自本教程）。当我运行这个主题的第一个消费者时，一切正常：
curl -X POST -H "Content-Type: application/vnd.kafka.v2+json" --data '{"name": "ci1", "format": "json", "auto.offset.reset": "earliest"}' http://localhost:8082/consumers/cg1
curl -X POST -H "Content-Type: application/vnd.kafka.v2+json" --data '{"topics":["purchases2"]}' http://localhost:8082/consumers/cg1/instances/ci1/subscription
curl -X GET -H "Accept: application/vnd.kafka.json.v2+json" "http://localhost:8082/consumers/cg1/instances/ci1/records"
但如果我尝试运行第二个消费者（新ID）并获取行：
curl -X POST -H "Content-Type: application/vnd.kafka.v2+json" --data '{"name": "ci2", "format": "json", "auto.offset.reset": "earliest"}' http://localhost:8082/consumers/cg1
curl -X POST -H "Content-Type: application/vnd.kafka.v2+json" --data '{"topics":["purchases2"]}' http://localhost:8082/consumers/cg1/instances/ci2/subscription
curl -X GET -H "Accept: application/vnd.kafka.json.v2+json" "http://localhost:8082/consumers/cg1/instances/ci2/records"
我收到很多消息（在 Kafka REST 日志中），例如：“请求加入组原因是：组已在重新平衡”：
rest-proxy | [2023-09-21 09:58:12,367] INFO [Consumer clientId=consumer-cg1-1, groupId=cg1] Request joining group due to: group is already rebalancing (org.apache.kafka.clients.consumer.internals.ConsumerCoordinator)
rest-proxy | [2023-09-21 09:58:15,391] INFO [Consumer clientId=consumer-cg1-1, groupId=cg1] Request joining group due to: group is already rebalancing (org.apache.kafka.clients.consumer.internals.ConsumerCoordinator)
rest-proxy | [2023-09-21 09:58:17,911] INFO [Consumer clientId=consumer-cg1-2, groupId=cg1] JoinGroup failed: The coordinator is not aware of this member. Need to re-join the group. Sent generation was Generation{generationId=-1, memberId='consumer-cg1-2-c3f649ce-934c-4e8a-a87a-d2e85ac82b54', protocol='null'} (org.apache.kafka.clients.consumer.internals.ConsumerCoordinator)
rest-proxy | [2023-09-21 09:58:17,911] INFO [Consumer clientId=consumer-cg1-2, groupId=cg1] Resetting generation and member id due to: encountered UNKNOWN_MEMBER_ID from JOIN_GROUP response (org.apache.kafka.clients.consumer.internals.ConsumerCoordinator)
rest-proxy | [2023-09-21 09:58:17,912] INFO [Consumer clientId=consumer-cg1-2, groupId=cg1] Request joining group due to: encountered UNKNOWN_MEMBER_ID from JOIN_GROUP response (org.apache.kafka.clients.consumer.internals.ConsumerCoordinator)
rest-proxy | [2023-09-21 09:58:17,913] INFO [Consumer clientId=consumer-cg1-2, groupId=cg1] Request joining group due to: rebalance failed due to 'The coordinator is not aware of this member.' (UnknownMemberIdException) (org.apache.kafka.clients.consumer.internals.ConsumerCoordinator)
rest-proxy | [2023-09-21 09:58:17,915] INFO [Consumer clientId=consumer-cg1-2, groupId=cg1] (Re-)joining group (org.apache.kafka.clients.consumer.internals.ConsumerCoordinator)
rest-proxy | [2023-09-21 09:58:17,919] INFO [Consumer clientId=consumer-cg1-2, groupId=cg1] Request joining group due to: need to re-join with the given member-id: consumer-cg1-2-ff236f69-f902-4294-847a-8bf4940354ef (org.apache.kafka.clients.consumer.internals.ConsumerCoordinator)
rest-proxy | [2023-09-21 09:58:17,919] INFO [Consumer clientId=consumer-cg1-2, groupId=cg1] Request joining group due to: rebalance failed due to 'The group member needs to have a valid member id before actually entering a consumer group.' (MemberIdRequiredException) (org.apache.kafka.clients.consumer.internals.ConsumerCoordinator)
rest-proxy | [2023-09-21 09:58:17,919] INFO [Consumer clientId=consumer-cg1-2, groupId=cg1] (Re-)joining group (org.apache.kafka.clients.consumer.internals.ConsumerCoordinator)
rest-proxy | [2023-09-21 09:58:18,414] INFO [Consumer clientId=consumer-cg1-1, groupId=cg1] Request joining group due to: group is already rebalancing (org.apache.kafka.clients.consumer.internals.ConsumerCoordinator)
rest-proxy | [2023-09-21 09:58:21,439] INFO [Consumer clientId=consumer-cg1-1, groupId=cg1] Request joining group due to: group is already rebalancing (org.apache.kafka.clients.consumer.internals.ConsumerCoordinator)
rest-proxy | [2023-09-21 09:58:24,461] INFO [Consumer clientId=consumer-cg1-1, groupId=cg1] Request joining group due to: group is already rebalancing (org.apache.kafka.clients.consumer.internals.ConsumerCoordinator)
rest-proxy | [2023-09-21 09:58:27,488] INFO [Consumer clientId=consumer-cg1-1, groupId=cg1] Request joining group due to: group is already rebalancing (org.apache.kafka.clients.consumer.internals.ConsumerCoordinator)
rest-proxy | [2023-09-21 09:58:30,511] INFO [Consumer clientId=consumer-cg1-1, groupId=cg1] Request joining group due to: group is already rebalancing (org.apache.kafka.clients.consumer.internals.ConsumerCoordinator)
rest-proxy | [2023-09-21 09:58:33,535] INFO [Consumer clientId=consumer-cg1-1, groupId=cg1] Request joining group due to: group is already rebalancing (org.apache.kafka.clients.consumer.internals.ConsumerCoordinator)
rest-proxy | [2023-09-21 09:58:36,560] INFO [Consumer clientId=consumer-cg1-1, groupId=cg1] Request joining group due to: group is already rebalancing (org.apache.kafka.clients.consumer.internals.ConsumerCoordinator)
rest-proxy | [2023-09-21 09:58:38,475] WARN [Consumer clientId=consumer-cg1-1, groupId=cg1] consumer poll timeout has expired. This means the time between subsequent calls to poll() was longer than the configured max.poll.interval.ms, which typically implies that the poll loop is spending too much time processing messages. You can address this either by increasing max.poll.interval.ms or by reducing the maximum size of batches returned in poll() with max.poll.records. (org.apache.kafka.clients.consumer.internals.ConsumerCoordinator)
rest-proxy | [2023-09-21 09:58:38,475] INFO [Consumer clientId=consumer-cg1-1, groupId=cg1] Member consumer-cg1-1-9dc34071-0a6d-4fce-8e11-9e18c6bbc372 sending LeaveGroup request to coordinator broker:29092 (id: 2147483646 rack: null) due to consumer poll timeout has expired. (org.apache.kafka.clients.consumer.internals.ConsumerCoordinator)
rest-proxy | [2023-09-21 09:58:38,477] INFO [Consumer clientId=consumer-cg1-1, groupId=cg1] Resetting generation and member id due to: consumer pro-actively leaving the group (org.apache.kafka.clients.consumer.internals.ConsumerCoordinator)
rest-proxy | [2023-09-21 09:58:38,477] INFO [Consumer clientId=consumer-cg1-1, groupId=cg1] Request joining group due to: consumer pro-actively leaving the group (org.apache.kafka.clients.consumer.internals.ConsumerCoordinator)
rest-proxy | [2023-09-21 09:58:38,482] INFO [Consumer clientId=consumer-cg1-2, groupId=cg1] Successfully joined group with generation Generation{generationId=38, memberId='consumer-cg1-2-ff236f69-f902-4294-847a-8bf4940354ef', protocol='range'} (org.apache.kafka.clients.consumer.internals.ConsumerCoordinator)
rest-proxy | [2023-09-21 09:58:38,484] INFO [Consumer clientId=consumer-cg1-2, groupId=cg1] Finished assignment for group at generation 38: {consumer-cg1-2-ff236f69-f902-4294-847a-8bf4940354ef=Assignment(partitions=[purchases2-0, purchases2-1])} (org.apache.kafka.clients.consumer.internals.ConsumerCoordinator)
rest-proxy | [2023-09-21 09:58:38,495] INFO [Consumer clientId=consumer-cg1-2, groupId=cg1] Successfully synced group in generation Generation{generationId=38, memberId='consumer-cg1-2-ff236f69-f902-4294-847a-8bf4940354ef', protocol='range'} (org.apache.kafka.clients.consumer.internals.ConsumerCoordinator)
rest-proxy | [2023-09-21 09:58:38,498] INFO [Consumer clientId=consumer-cg1-2, groupId=cg1] Notifying assignor about the new Assignment(partitions=[purchases2-0, purchases2-1]) (org.apache.kafka.clients.consumer.internals.ConsumerCoordinator)
rest-proxy | [2023-09-21 09:58:38,498] INFO [Consumer clientId=consumer-cg1-2, groupId=cg1] Adding newly assigned partitions: purchases2-0, purchases2-1 (org.apache.kafka.clients.consumer.internals.ConsumerCoordinator)
rest-proxy | [2023-09-21 09:58:38,506] INFO [Consumer clientId=consumer-cg1-2, groupId=cg1] Setting offset for partition purchases2-0 to the committed offset FetchPosition{offset=11, offsetEpoch=Optional[0], currentLeader=LeaderAndEpoch{leader=Optional[broker:29092 (id: 1 rack: null)], epoch=0}} (org.apache.kafka.clients.consumer.internals.ConsumerCoordinator)
rest-proxy | [2023-09-21 09:58:38,506] INFO [Consumer clientId=consumer-cg1-2, groupId=cg1] Setting offset for partition purchases2-1 to the committed offset FetchPosition{offset=22, offsetEpoch=Optional[0], currentLeader=LeaderAndEpoch{leader=Optional[broker:29092 (id: 1 rack: null)], epoch=0}} (org.apache.kafka.clients.consumer.internals.ConsumerCoordinator)
重新平衡和消息持续大约 max.poll.interval.ms ，而第一个消费者将被删除。在此期间，没有人可以从主题获取数据。并且第二个消费者仅在第一个消费者因超时（max.poll.interval.ms）被踢出时才连接。每次我尝试启动任何第二个消费者时，都会重复此操作。主题有 2 个分区，通常有两个消费者，每个分区一个。但出于某种原因，我无法激活第二个消费者。
答案1
该问题在Kafka REST版本：7.3.0中出现，在7.5.0版本中该问题得到解决。
对于 Kafka REST 6.2.7 情况相同，但日志中出现另一条消息：
Attempt to heartbeat failed since group is rebalancing