Why do we need msgio.pool ? replace msgio with delimited?

[y0sher]

https://github.com/google/kythe/blob/master/kythe/go/platform/delimited/delimited.go

Delimited is a file written by google in the kythe project to do prefix length delimited read/write operations.
can you see any better reason to use msgio over that ? I don't really see why pools are important..

[Stebalien]

So, we need to reuse buffers somehow. If we don't, GC gets very unhappy due to too many short-lived allocations.

delimited does this by reusing a single buffer for each connection. Unfortunately, go-libp2p tends to keep around >500 connections (with a bunch of streams multiplexed on-top) and the messages we send can be up quire large (e.g., 256KiB or even 1MiB). If we had to keep a 256KiB buffer around for each connection, we'd end up wasting a ton of memory.

Instead, msgio reads the length of the next message using a small buffer and then grabs a buffer of the appropriate size from the buffer pool. This way, we don't have to lock-up a large buffer for every idle connection.