MINI TASK MANAGER

Find what's eating your CPU and kill it, from the panel.

An applet for the COSMIC™ desktop.

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A small process monitor that lives in the COSMIC panel. Click it and you get CPU and memory usage, a list of what's running, and buttons to stop, resume, or kill anything misbehaving, without opening a full system monitor or reaching for htop.

It exists because the thing I actually wanted from a task manager, 95% of the time, was "which process is eating my CPU, and can I kill it right now".

What it does

The panel button shows current CPU usage. It goes amber past 75%, and if something is stopped or unresponsive it turns red and shows a count instead, so you notice without opening anything.

Inside the popup:

• CPU and memory meters for the whole system, refreshed on a timer.
• Five tabs. All and Apps sort by CPU but float anything stopped or hung to the top. Top CPU and Top RAM sort purely by that one column. Stopped / Hung shows only the processes worth worrying about.
• Search across process name, full command line, and PID.
• Per-process actions. Stop (SIGSTOP), Resume (SIGCONT), Kill (SIGKILL). Which buttons appear depends on the state; a stopped process offers Resume, a zombie only offers Kill.
• Kill takes the whole tree. Killing a process kills its children and their children too, so you don't get orphans left running. Killing a browser or a file manager takes its helper processes with it instead of stranding them.
• Kill All, in the warning banner, for when several things have wedged at once.

GUI applications are matched against installed .desktop files, so they show their real name and icon instead of a binary name. Everything else gets a generic icon.

Installing

Arch, CachyOS, and other Arch-based distros

git clone https://github.com/Kai-J-G/cosmic-ext-mini-taskmanager.git
cd cosmic-ext-mini-taskmanager
makepkg -si

This builds a release binary and installs it, plus the desktop entry, AppStream metadata, icons, and licence, under /usr.

With just

Installs into ~/.local, no root needed:

just install

System-wide instead:

sudo just prefix=/usr install

And to remove it:

just uninstall

With cargo directly

cargo build --release
install -Dm0755 target/release/cosmic-ext-mini-taskmanager ~/.local/bin/cosmic-ext-mini-taskmanager
install -Dm0644 data/io.github.kai_j_g.MiniTaskManager.desktop ~/.local/share/applications/io.github.kai_j_g.MiniTaskManager.desktop
install -Dm0644 data/io.github.kai_j_g.MiniTaskManager.metainfo.xml ~/.local/share/metainfo/io.github.kai_j_g.MiniTaskManager.metainfo.xml
install -Dm0644 data/icons/io.github.kai_j_g.MiniTaskManager.svg ~/.local/share/icons/hicolor/scalable/apps/io.github.kai_j_g.MiniTaskManager.svg
install -Dm0644 data/icons/io.github.kai_j_g.MiniTaskManager-symbolic.svg ~/.local/share/icons/hicolor/scalable/apps/io.github.kai_j_g.MiniTaskManager-symbolic.svg

Adding it to the panel

Open COSMIC Settings, then Desktop → Panel → Applets, click Add Applet, and pick Mini Task Manager. Drag it wherever you want it.

You can also just run cosmic-ext-mini-taskmanager from a terminal, which gives you the panel button as a floating window. Useful for checking a build, less useful day to day.

Settings

Click the gear in the popup header:

Setting	Options	Default
Appearance	System, Dark, Light	System
Refresh interval	1s, 2s, 5s	2s
Panel warning indicator	on / off	on

Settings are stored via cosmic-config, so they survive restarts. Picking Dark or Light pins the popup to that theme even if you later flip the desktop's own light/dark switch; System follows the desktop.

Languages

Eight languages, as embedded Fluent catalogs, with no runtime files to install. The desktop's language is picked up automatically, falling back to English.

English · Français · Deutsch · Español · Italiano · Português · 日本語 · 简体中文

Translations live in i18n/. To add one, copy i18n/en/cosmic_ext_mini_taskmanager.ftl into a new locale directory and translate the values. A test asserts that every catalog defines every message English does, so a partial translation fails cargo test rather than falling back to English mid-sentence.

Things worth knowing

• You can only signal your own processes. Anything owned by root or another user returns "Operation not permitted", which shows up in the status line at the foot of the popup. The applet doesn't ask for privilege escalation.
• Kill is SIGKILL, and it takes descendants with it. There's no "terminate gracefully first" step, so nothing killed this way saves its work. That's deliberate: it's the button you press when asking nicely has already failed. The descendant list is captured before the root dies, since children are reparented to init the moment it does. Note that killing something far up the tree takes everything under it: kill your session leader and you end your session.
• CPU is a share of the whole machine, not of one core. A single-threaded process pegging one core on a 16-core box reads as about 6%, not 100%, so the rows add up to the figure in the header. If you're used to htop's per-core numbers, multiply by your core count.
• Threads aren't listed separately. sysinfo reports them alongside processes on Linux, and a userland thread carries its process's command line, so they used to appear as duplicate rows with their CPU counted twice.
• "Hung" means two consecutive polls in uninterruptible sleep. A single poll in D state is just a normal disk read, so a process has to stay there to get flagged.
• The list renders at most 80 rows. The toolkit builds every widget in the tree each frame, so an unbounded list would cost real frame time on a machine with hundreds of processes. The tabs and the search box are how you reach the rest.
• Kernel threads are hidden. They have no command line and aren't yours to manage.
• Memory is reported in binary units (MiB, GiB), matching what the kernel reports.
• Swap isn't shown anywhere.

Building from source

Needs a Rust toolchain and the usual COSMIC build dependencies.

cargo build --release

cargo test

The test suite covers signal dispatch, process-tree walking, filtering and sort ordering, byte formatting, translation completeness, and building the full widget tree for every tab against deliberately hostile process data: long command lines, multi-byte characters, NaN CPU values, and empty names.

Two tests spawn a real three-level process tree: one asserts that killing only the root does leave orphans, the other that the sweep doesn't. The first exists so the second can't quietly stop proving anything.

Layout

src/
├── main.rs                 entry point
├── app.rs                  state, update loop, subscriptions
├── config.rs               persisted settings
├── localize.rs             Fluent catalog loading
├── process/
│   ├── types.rs            process, state, and overview models; process-tree walk
│   ├── collector.rs        sysinfo polling, .desktop matching, filtering, sorting
│   └── actions.rs          SIGSTOP / SIGCONT / SIGKILL
└── views/
    ├── mod.rs              popup composition
    ├── panel.rs            panel button and popup surface
    ├── header.rs           CPU and RAM meters
    ├── filter_bar.rs       search and tabs
    ├── alert_banner.rs     warning banner and Kill All
    ├── process_row.rs      one process row
    ├── settings.rs         settings panel
    └── style.rs            container and badge styling

Built on libcosmic, which means the Elm-style model/update/view pattern from iced. Process data comes from sysinfo.

Ideas for later

Per-process disk and network I/O. A collapsible parent/child process tree in the list itself. Cgroup CPU and memory limits, so you could throttle something instead of killing it. A global shortcut to summon the popup.

Licence

MIT. See LICENSE.

COSMIC™ is a trademark of System76. This is a third-party applet, not official COSMIC software and not endorsed by System76. It uses the cosmic-ext- package namespace that System76's trademark policy asks third-party developers to use.

Dependencies keep their own licences. The two that matter most here are libcosmic, which is MPL-2.0, and sysinfo, which is MIT. MPL-2.0 is file-level copyleft: linking it into this MIT-licensed binary is fine, but if you modify libcosmic's own source you have to publish those changes. cargo tree will show you the full dependency set.