It takes too long to subscribe to a topic #6363
Description
Describe the bug
It takes more than 4s to subscribe to a topic. Sometimes it takes more than 10s. Most of the time was spent starting the replicator.
Broker log
There are logs about topic persistent://2/signal_geo/1579404480244 from the broker.
11:28:00.295 [bookkeeper-ml-workers-OrderedExecutor-0-0] INFO org.apache.pulsar.broker.service.persistent.PersistentTopic - [persistent://2/signal_geo/1579404480244] There are no replicated subscriptions on the topic
11:28:00.295 [bookkeeper-ml-workers-OrderedExecutor-0-0] DEBUG org.apache.pulsar.broker.service.persistent.PersistentTopic - [persistent://2/signal_geo/1579404480244] Checking replication status
11:28:00.295 [bookkeeper-ml-workers-OrderedExecutor-0-0] INFO org.apache.pulsar.broker.service.persistent.PersistentTopic - [persistent://2/signal_geo/1579404480244] Starting replicator to remote: qa-pulsar-ali
11:28:00.297 [pulsar-io-22-5] DEBUG org.apache.pulsar.broker.service.ServerCnx - [persistent://2/signal_geo/1579404480197] Received Lookup from /10.32.69.26:35808 for 141589
11:28:00.319 [pulsar-io-22-4] DEBUG org.apache.pulsar.broker.service.ServerCnx - [persistent://2/signal_geo/1579404480229] Received PartitionMetadataLookup from /10.32.69.26:35566 for 141591
11:28:00.323 [pulsar-io-22-11] DEBUG org.apache.pulsar.broker.service.ServerCnx - [persistent://2/signal_geo/1579404480229] Received Lookup from /10.32.69.26:35448 for 141592
11:28:04.347 [bookkeeper-ml-workers-OrderedExecutor-0-0] INFO org.apache.pulsar.broker.service.AbstractReplicator - [persistent://2/signal_geo/1579404480244][qa-pulsar-ten -> qa-pulsar-ali] Starting replicator
11:28:04.348 [bookkeeper-ml-workers-OrderedExecutor-0-0] INFO org.apache.pulsar.broker.service.BrokerService - Created topic persistent://2/signal_geo/1579404480244 - dedup is disabled
11:28:04.349 [bookkeeper-ml-workers-OrderedExecutor-0-0] DEBUG org.apache.pulsar.broker.service.persistent.PersistentTopic - [persistent://2/signal_geo/1579404480244] [10.32.68.229:8787:18672:1579404480289] [mfhzn] Added consumer – count: 1