Would be nice to have a event when the queue is empty.

[littlebee]

The use case is that I have millions of rows in a table (T1) and I need to query T1 and then query a another table (T2) which has 0-4 rows per row in the first. I need to not let T2 grow too much and I want to fire off a batch of queries and then wait until they finish and then queue up some of the T2 queries.

It's a fairly simple mod.

[dresende]

Isn't this related to #271 ?

[dresende]

Such event will be created, but probably named drain as other core node events are called. Keeping this open for now as your code seems cleaner than the other drain event pull requests.

[grncdr]

Could you explain what you mean by "not let T2 grow too much"? TBH I don't really understand why your scenario requires a 'drain' event, some sample code illustrating the way it works with your proposed change would really help.

[dresende]

I think she means she doesn't want to drag the server down with millions of queries, so the goal is to make a batch of queries, then wait for them to finish, possibly wait a bit and then batch more queries, and so on..