Show HN: PicoMQ – Durable Streams over HTTP, on object storage

Thank you! I spent a decent chunk of time designing PicoMQ, so the documentation had a natural progression.

Exactly, streams can essentially be rooms, and since the ordering is preserved, a Discord-like application is a strong use case. I’m even considering building one using PicoMQ as an example showcase.

The pricing is going to be dirt cheap, and the best part is how easy it is to scale up vertically or add nodes. For some raw numbers, assuming 1M messages/day, 200B per message, ~6GB/month, all-inclusive, it would be $30 to $150 a month, and storage would be the cheapest part.

I'm glad you asked, and yes, PicoMQ does have some Kafka-like semantics. However, Kafka is great at being a huge pipe, so you'd create topics like tables. PicoMQ, on the other hand, recommends creating granular streams that make the most sense, say, by user, session, or vehicle (still bottomless).

And it's also fair to question write performance, since it's backed by object storage. The optimization is primarily from the shared WAL across streams, server-side batching, and client-side in-memory pipelining, especially with HTTP/2, without as much connection pool overhead.

In practice, you can go to the extent of achieving up to 100 MiB/s throughput per stream. Considering how granular streams can be, you'd rarely need as much. The latency for a durability ACK is, however, the price to pay, which is going to be ~250 ms, or lower with S3 Express, which I'd say covers most real-time use-cases. The design itself is easy enough to extend to a disk-staged WAL for single-digit durability ACK latency.

Not familiar with this particular library, but similar libraries use S3 Express One Zone which has write latency <10ms, so you can use that for the WAL and compaction can move data onto other storage classes in the background.

Regular S3 has write latency 100-150ms, which might be fine depending on your workload anyway.