Python-Kafka：使用者失败

Question

I have a simple Producer-Consumer setup: 1 producer(as a thread) and 2 consumers(as 2 processes). The run method of producer:

    def run(self):
        producer = KafkaProducer(bootstrap_servers=self.bootstrap_servers, 
                                 api_version=(0, 10))
        while not self.stop_event.is_set():
           self.logger.info("Checking for new changes")
           self.check_for_new_changes(producer)
           self.logger.info("Sleeping for {minutes} 
                          minutes...".format(minutes=self.time_to_sleep / 60))
           time.sleep(self.time_to_sleep)
        producer.close()

Basically it checks for changes, sends messages if new changes found and then goes to sleep for 5 minutes.

The run method:

def run(self):
    if self.group_id:
        consumer = KafkaConsumer(bootstrap_servers=self.bootstrap_servers,
                                 consumer_timeout_ms=1000,
                                 api_version=(0, 10),
                                 group_id=self.group_id)
    else:
        consumer = KafkaConsumer(bootstrap_servers=self.bootstrap_servers,
                                 consumer_timeout_ms=1000,
                                 api_version=(0, 10))
    consumer.subscribe(['new_change'])
    while not self.stop_event.is_set():
        for msg in consumer:
            self.logger.info("New message:\n{msg}".format(msg=msg))
            self.process_new_change(json.loads(msg.value))
            if self.stop_event.is_set():
                consumer.close()
                return
    consumer.close()

It seems to work fine but after running for a while I get these messages in the coordinator log:

[2017-12-17 02:06:40,639] INFO [GroupCoordinator 0]: Member kafka-python-1.3.5-f5cdcad3-bc1a-4623-a42b-f5de5e8bded1 in group meta_data_consumer has failed, removing it from the group (kafka.coordinator.group.GroupCoordinator)
[2017-12-17 02:06:40,659] INFO [GroupCoordinator 0]: Preparing to rebalance group meta_data_consumer with old generation 15 (__consumer_offsets-6) (kafka.coordinator.group.GroupCoordinator)
[2017-12-17 02:06:40,659] INFO [GroupCoordinator 0]: Group meta_data_consumer with generation 16 is now empty (__consumer_offsets-6) (kafka.coordinator.group.GroupCoordinator)
[2017-12-17 02:06:41,784] INFO [GroupCoordinator 0]: Member kafka-python-1.3.5-bdea8ce3-922f-4ee1-9959-13341e1730f5 in group failures_consumer has failed, removing it from the group (kafka.coordinator.group.GroupCoordinator)
[2017-12-17 02:06:41,785] INFO [GroupCoordinator 0]: Preparing to rebalance group failures_consumer with old generation 9 (__consumer_offsets-35) (kafka.coordinator.group.GroupCoordinator)
[2017-12-17 02:06:41,785] INFO [GroupCoordinator 0]: Group failures_consumer with generation 10 is now empty (__consumer_offsets-35) (kafka.coordinator.group.GroupCoordinator)

This kills my consumers and they stop running. I don't see any exceptions or errors in the consumer logs.

What might cause them to fail?

Answer 1

I think your zookeeper.session.timeout.ms is set lower than 5 minutes. Adjust that timeout from zookeeper settings. See if it still fails. If it does, then you should adjust the timeouts in kafka configs. group.max.session.timeout.ms , rebalance.timeout.ms , heartbeat.interval.ms should be adjusted accordingly. Your client sleeps for 5 minutes, and during that time, one of those timeout value is exceeded, and Group Coordinator tries to rebalance the consumer, thinking those consumers have failed.

Source: Kafka Documentation