[synchrone]

I searched all over the web for a reliable and scalable plain message queue that could work in a full disk-backed mode, not requiring the data to fit in memory.

Was very impressed with how little RAM and CPU it consumed under load.

[polskibus]

Does it offer any delivery guarantees?

[synchrone]

As far as I read the docs, if you use 0 for memory storage size - it will flush to disk before responding that the message was published OK.

Delivery is "at least once".

[NicoJuicy]

Did you check out NATS?

[synchrone]

Was using it in production before. NATS itself is great and reliable.

However disk persistency is done with nats-streaminh and i had big issues with it's Raft file based store, where it would stop accepting messages after a short network issue, and not get unstuck unless I destroy the whole nats-streaming data storage amd start from scratch.

Also raft means 3x disk usage for one queue, since its fully replicated

[tapirl]

Both nsq and nats are very memory saving.