Thought - How Atom built its own Assassin?
They built a runtime that allowed developers to create desktop applications using the web stack (HTML, CSS, JavaScript). They called it Atom Shell (Electron).
In the history of software engineering, there is no story more tragic than that of Atom.
In 2014, GitHub unveiled Atom to the world with a tagline that promised utopia, “A hackable text editor for the 21st Century.”
To realize this vision, the GitHub engineering team performed a miracle.
They built a runtime that allowed developers to create desktop applications using the web stack (HTML, CSS, JavaScript). They called it Atom Shell.
Today we know it as Electron.
Atom didn’t just build an editor, they built the foundation for the next decade of software.
Slack, Discord, Figma, they all stand on the shoulders of Atom Shell.
But in a twist of cruel irony, a sleeping giant in Redmond picked up this exact tool, identified the one fatal flaw Atom refused to fix, and used it to build Visual Studio Code.
Atom provided the gun, the bullets, and the blueprint.
Microsoft simply pulled the trigger.
The Single-Threaded Trap
To understand why Atom died, we must look past the “bloat” complaints and analyze the Concurrency Model.
Atom’s core philosophy was Total Freedom.
They wanted the editor to be truly hackable.
This meant that a plugin developer could access everything.
They had direct access to the DOM. They shared the global scope.
Crucially, they ran on the Main Thread.
In a single-threaded environment like JavaScript, the Main Thread is holy ground.
It is responsible for event loops, layout calculations, and painting pixels.
By allowing plugins to inhabit this space, Atom created a zero-sum game for CPU cycles.
You install a “Bracket Matcher” plugin.
You type a bracket. The plugin wakes up to find the matching pair. It runs a synchronous search that takes 50ms.
For those 50ms, the UI renderer is blocked. The cursor stops blinking. The character you typed hangs in the buffer.
The “heaviness” users complained about was not memory usage, it was Thread Contention.
Atom relied on the “goodwill” of plugin authors to write non-blocking code. It was an architectural gamble that assumed developers would be disciplined.
They were not.
VS Code’s Architecture (Extension Host)
When Microsoft architected VS Code, led by Erich Gamma (one of the “Gang of Four”), they looked at Atom’s freedom and rejected it.
They prioritized Isolation over Hackability.
They introduced the Extension Host Process.
In VS Code, the editor UI runs in the Main Process and all the extensions run in a completely separate Node.js process.
There is a hard, impassable barrier between them.
An extension cannot access the DOM.
An extension cannot access the window object.
An extension cannot freeze the renderer.
If a VS Code extension enters an infinite loop or tries to mine crypto, the Extension Host might crash, but the user can still type. The cursor still blinks.
The “Hot Path” (the keystroke loop) is protected at all costs.
RPC vs. Shared State
This decision created a massive engineering trade-off.
Atom’s Model (Shared State)
Latency was near zero. A plugin can read the document buffer instantly from memory.
But it has volatile stability. One bad plugin kills the app.
VS Code’s Model (RPC)
Latency was high overhead. Since the plugin is in a different process, data must be serialized into JSON, sent over an IPC (Inter-Process Communication) pipe, deserialized, processed, reserialized, and sent back.
But it guaranteed stability. App will keep running even a bad plugin is installed.
Why constraints won?
VS Code bet that Input Latency was the only metric that mattered.
Users can tolerate a 100ms delay in syntax highlighting appearing.
But, they cannot tolerate a 10ms delay in a character appearing on screen.
By forcing communication through Asynchronous RPC, VS Code enforced “Mechanical Sympathy.” It acknowledged the reality of the JavaScript event loop and refused to fight it.
Atom tried to pretend the Main Thread was infinite.
Constraints are Features
The downfall of Atom teaches us a critical lesson in System Design
Constraints are often more valuable than capabilities.
Atom failed because it offered Total Freedom.
It gave developers a foot-gun, and developers proceeded to shoot the performance in the foot.
VS Code succeeded because it imposed Strict Constraints.
It built a sandbox that prevented developers from hurting the user experience, even if they wanted to.
Conclusion
In 2022, GitHub (now owned by Microsoft) officially sunset Atom.
Atom did not die in vain. It was the martyr of the modern web desktop.
It proved the hypothesis that Electron could work.
It served as the glorious, messy prototype that paved the way for the production-grade architecture of VS Code.
Atom died so the ecosystem could live. And in the ruthless history of engineering, the prototype always gets deprecated.