Datarace in partitionConsumer

[XuanYang-cn]

Expected behavior

Tell us what should happen

Actual behavior

==================
WARNING: DATA RACE
Write at 0x00c000357e28 by goroutine 42:
  github.com/apache/pulsar-client-go/pulsar.(*partitionConsumer).grabConn()
      /go/pkg/mod/github.com/apache/pulsar-client-go@v0.5.0/pulsar/consumer_partition.go:970 +0x17c6
  github.com/apache/pulsar-client-go/pulsar.(*partitionConsumer).reconnectToBroker()
      /go/pkg/mod/github.com/apache/pulsar-client-go@v0.5.0/pulsar/consumer_partition.go:883 +0x238
  github.com/apache/pulsar-client-go/pulsar.(*partitionConsumer).runEventsLoop.func2()
      /go/pkg/mod/github.com/apache/pulsar-client-go@v0.5.0/pulsar/consumer_partition.go:787 +0xab

Previous read at 0x00c000357e28 by goroutine 119:
  github.com/apache/pulsar-client-go/pulsar.(*partitionConsumer).internalClose()
      /go/pkg/mod/github.com/apache/pulsar-client-go@v0.5.0/pulsar/consumer_partition.go:854 +0x687
  github.com/apache/pulsar-client-go/pulsar.(*partitionConsumer).runEventsLoop()
      /go/pkg/mod/github.com/apache/pulsar-client-go@v0.5.0/pulsar/consumer_partition.go:808 +0x29b

Goroutine 42 (running) created at:
  github.com/apache/pulsar-client-go/pulsar.(*partitionConsumer).runEventsLoop()
      /go/pkg/mod/github.com/apache/pulsar-client-go@v0.5.0/pulsar/consumer_partition.go:780 +0x146

Goroutine 119 (finished) created at:
  github.com/apache/pulsar-client-go/pulsar.newPartitionConsumer()
      /go/pkg/mod/github.com/apache/pulsar-client-go@v0.5.0/pulsar/consumer_partition.go:208 +0xf3a
  github.com/apache/pulsar-client-go/pulsar.(*consumer).internalTopicSubscribeToPartitions.func1()
      /go/pkg/mod/github.com/apache/pulsar-client-go@v0.5.0/pulsar/consumer_impl.go:326 +0x778
==================

Tell us what happens instead

Steps to reproduce

How can we reproduce the issue

System configuration

Pulsar version: latest docker image

[leizhiyuan]

#535

It seems that has been fixed in 0.6.0