rusm-otp

The Wasm-free Erlang/OTP core of RUSM — real lightweight processes, message passing, supervision, and connectivity, in pure Rust on Tokio.

rusm-otp is the heart of RUSM: a from-scratch, BEAM-inspired actor runtime built on Tokio, with no dependency on WebAssembly (it's usable entirely standalone). Each process is a Tokio task scheduled M:N over a few OS threads; the goal is hundreds of thousands of spawns per second.

What it gives you

• Processes & scheduling — spawn, abort-based lifecycle, a sharded-DashMap process table.
• Mailboxes & messaging — per-process mailbox, send/receive, selective receive, receive … after timeouts.
• Links, monitors, supervision — exit reasons, link/monitor/trap_exit/spawn_link/exit, exit cascades, supervisors with windowed restart intensity.
• Process management — a named registry, process groups (Erlang pg: register_tag/whereis_tag/kill_tag — tag many processes, terminate the group), timers (send_after/cancel), graceful shutdown, introspection (list/info/set_label).
• Connectivity — TCP (listen/connect, one process per connection) and back-pressured byte streams (Received::Stream).

Exit signals ride the mailbox (a Received enum) and kill rides a futures abort handle — one channel per process. The same core powers the rusm-cluster distributed transport and, via rusm-wasm, hosts sandboxed WebAssembly processes.

use rusm_otp::Runtime;

let rt = Runtime::new();
let pid = rt.spawn(|mut ctx| async move {
    while let Some(msg) = ctx.recv().await.message() { /* handle */ }
});
rt.send(pid, b"hello".to_vec());

Part of RUSM. See the repo README and the architecture docs.