If we publish two stream objects to two different topics, they should be able to run in parallel.

[bgood]

If we publish two stream objects to two different topics, they should be able to run in parallel, right? However, the current code only allows a single go routine to publish a message. We can change this to:

mux.Lock()
topic, ok := mClients[topicName]
if !ok {
	topic = pubsubClient.c.
		TopicInProject(topicName, config.ConfigurationMap.GOOGLE_PROJECT_ID)
	mClients[topicName] = topic
}
mux.Unlock()

message := &pubsub.Message{}
message.Data, _ = json.Marshal(streamObj)
_, err := topic.Publish(context.Background(), message).Get(ctx)
if err != nil {
	logger.LogError(err)
}

topic.Publish is a thread-safe method: https://github.com/googleapis/google-cloud-go/blob/pubsub/v1.8.2/pubsub/topic.go#L434-L435 (t.scheduler also has an internal sync.Mutex).

Originally posted by @hengfengli in #3 (comment)