[GitHub] [pulsar] BJTiso opened a new issue #4361: Go client: multi-topic unsubscribe hangs when regex does not match any topics

[GitBox <gi...@apache.org>]

BJTiso opened a new issue #4361: Go client: multi-topic unsubscribe hangs when regex does not match any topics
URL: https://github.com/apache/pulsar/issues/4361
 
 
   **Describe the bug**
   When performing multi-topic unsubscribe on a topic regex that does not not match any topics, then Unsubscribe call will block indefinitely.
   
   
   **To Reproduce**
   Steps to reproduce the behavior:
   1. launch container ```apachepulsar/pulsar``` and listen on port 6650 on host
   
   2. use ```github.com/apache/pulsar/pulsar-client-go v0.0.0-20190517092409-1f4a836a46483db408e0bf39903215974262d946``` in go.mod which pulls 2.3.1 + build fix from #4212 for example:
   
   ```
   module pulsartest
   
   require github.com/apache/pulsar/pulsar-client-go v0.0.0-20190517092409-1f4a836a46483db408e0bf39903215974262d946
   ```
   
   3.  create test code to subscribe to erroneous multi-topic pattern 
   ```go
   package main
   
   import (
   	"github.com/apache/pulsar/pulsar-client-go/pulsar"
   	"log"
   	"runtime"
   )
   
   func main() {
   	client, err := pulsar.NewClient(pulsar.ClientOptions{
   		URL: "pulsar://localhost:6650",
   		OperationTimeoutSeconds: 5,
   		MessageListenerThreads: runtime.NumCPU(),
   	})
   	if err != nil {
   		log.Fatalf("Could not instantiate Pulsar client: %v", err)
   	}
   	msgChannel := make(chan pulsar.ConsumerMessage)
   	consumerOpts := pulsar.ConsumerOptions{
   		TopicsPattern:            "persistent://public/default/1-.*-fakefakefake",
   		SubscriptionName: "my-subscription-1",
   		Type:             pulsar.Exclusive,
   		MessageChannel:   msgChannel,
   	}
   	consumer, err := client.Subscribe(consumerOpts)
   	if err != nil {
   		log.Fatalf("Could not establish subscription: %v", err)
   	}
   	err = consumer.Unsubscribe()
   	if err != nil {
   		log.Fatalf("Could not establish subscription: %v", err)
   	}
   }
   ```
   3. ```go build && ./pulsartest``` to reproduce
   
   **Expected behavior**
   pulsartest will return
   
   **Actual behavior**
   pulsartest hangs indefinitely 

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