nsqd: --mem-queue-size=0 still creates memory channel

[bitpeng]

generally, we intend to save all the message in the disk-queue when set -mem-queue-size=0 option, but make(chan *Message, 0) just create a unbuffered chan which can also send/receive message as well.
the follow figure is my experiment test...

is it a bug?

[mreiferson]

It was never intended to be a strict guarantee, so I don't personally consider it a bug, but I would be willing to consider the change in #1159.

Let's continue the discussion there? Thanks!

[bitpeng]

Thanks for your warmly, patient answer, but in my opinion it should give the user an option to have a chance to save all the messages on the disk-queue. What about you? @mreiferson