This month in heim - August 2019

It’s been a month and a half since the heim public announcement, so it’s about time to sum up the work done and make a roadmap for next development iteration. As a quick reminder: heim is the Rust cross-platform async library for system information fetching — CPU, memory, disks, networks, you name it.

What’s new?

System processes

Querying system processes is now possible with the new heim::process module:

let current = heim::process::current().await?;

let mut processes = heim::process::processes();
while let Some(process) = {
    let process = process?;

    println!("Pid: {}",;
    if == {
        println!("It's-a me, Mario!");

    println!("Status: {:?}", process.status().await?);
    println!("Name: {}",;
    println!("Path to executable: {:?}", process.exe().await?);
    // …and many other methods available

heim::process API is a bit different from other heim::* modules, as it involves more async routines for data loading and includes the custom error type to handle unknown processes, zombies and such processes for which we do not have the permissions required.

Not all parts are implemented yet (see #106), but it is usable enough already to build your own top clone, as can be seen in the “New users” section below, so check the docs and examples for details.

Sensors prototype

Another experimental module heim::sensors is going to be responsible for temperature and fan sensors eventually, but fetching that information is amazingly painful, so there is only temperature sensors implementation for Linux is available for now.
It seems that for Windows it would require an async WMI client, which does not exist at all (wmi@13) and I’m not even sure if it is possible for macOS at all.

Unexpected side crates

As the processes querying for macOS requires interaction with the libproc library via FFI, that code was extracted from the heim sources and published separately as the darwin-libproc-sys and darwin-libproc crates, providing a low-level FFI bindings and idiomatic Rust wrappers correspondingly.

Both of them proudly carry the “experimental” status and covers only few parts of the libproc API, but that’s a start!

What’s next?

Missing heim::process parts will be the major goal for the next month.
Not only the missing “read” methods will be implemented, but the interaction methods too, like an ability to send signals to the processes, suspend, resume or even kill them.

Runtimes integration

Previous heim versions were calling sync operations directly in the async functions, which was bad, obviously, but worked good enough for early prototypes.
Starting from the 0.0.6 version, heim has its own thread pool to properly run blocking operations outside of a current execution thread.

It is better than nothing, but not as efficient as it might be, so it will be replaced with the async-std crate (#133) soon. I also do not like the idea of heim being bound to one specific async runtime, so there will be the tokio crate integration too (#82), which will allow heim users to choose what underlying implementation they want to use.

Fun time with async_await

I’m very excited that async_await feature is finally going to be released as a Rust 1.39 part, so starting from September heim will be slowly rewritten with async_await, which should reduce the lines of code amount and maintenance burden drastically. Unfortunately, minimal supported Rust version will be bumped to 1.39 then, which looks like a fair trade considering how insane it might be sometime to write futures combinators.

New users

Recently announced Nu Shell (a modern shell for the GitHub era) is using heim both for the ps and sys commands:

Nu is actively utilizing benefits of the async execution too, and heim integration allows it to load displayed data concurrently with ease, which is vital for a responsive shell and flawless user experience.

Jonathan Turner:

It was pretty straightforward to follow your examples. I think I moved to heim for sys in about an hour or so (+ time for testing across platforms)

Let me know if you are using heim too, I would love to hear about your experience!


heim is the open-source project I’m working on in my spare time. If you are appreciate it and want to support the project development, consider making a donation or becoming the OpenCollective backer/sponsor.