Address comments from #4395 #4379

[pellared]

Why we are closing the channel?

1. This is not needed
2. The consumer/receiver should never close the channel

Reference: https://go101.org/article/channel-closing.html

One general principle of using Go channels is don't close a channel from the receiver side and don't close a channel if the channel has multiple concurrent senders.

PS. I would rather use sync.WaitGroup like I suggest in another comment.

Originally posted by @pellared in #4395 (comment)

[pellared]

Look also at #4379 (comment)