Comment by caust1c | Hacker News Reader

Comment by caust1c | Hacker News Reader

Heh, funny that you mention that ZMQ is overlooked. While often though of a message passing library or serverless queue, Zero MQ has some pretty severe limitations that implementers fail to consider.

To be clear, I think it's an amazing library which is unmatched in its performance, but it comes at a cost: reduced reliability.

ZeroMQ will drop messages in a number of situations. The library does not handle delivery guarantees which means that the application must do it themselves. Whether or not this works for you is an application level concern. However, having used it at two companies now: both times it ended up being thrown out for a more reliable queue (kafka).

http://zguide.zeromq.org/py:all#Missing-Message-Problem-Solv...

So maybe the reason you haven't stumbled upon it sooner is because it's overhyped? Definitely useful but with a grain of salt.

The "MQ" part of the name is unfortunate, but apparently came about because of the original idea to come up with a "better" implementation of AMQP (http://zeromq.org/docs:welcome-from-amqp).

But you're right -- ZeroMQ doesn't do queueing (except in some very limited circumstances), and if you need reliable delivery you must implement that yourself "on top of" ZeroMQ. I've done that, and while it's not a simple task, it is certainly possible.

You can get reliable delivery "out of the box" with other software, that in fact does do queueing. (kafka may be one, but I don't know enough to say).

But what you give up when you do that is performance -- ZeroMQ can easily be orders of magnitude faster than those other solutions, and for some applications (e.g., real-time market data) the work to provide a custom reliability solution on top of ZeroMQ is worthwhile.

Yeah, every new user has to learn that ZMQ is not a proper queue, but simply a network library and protocol. How is it even possible to bungle the name so badly and then do nothing about it for twelve years?

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