Firebreak

About the Project

Firebreak is a native macOS utility that catches runaway process swarms before they cook the machine. Passive monitors show a temperature in the menu bar and leave the rest to you; Firebreak is process-tree aware. When an iOS Simulator spawns fifty poster extensions, a container runtime fans out workers, or an Electron app leaks helpers, no single process looks guilty, so Firebreak rolls every child PID up into the application that owns it, computes the cumulative load, and names the real culprit. From the menu bar you can freeze the whole tree with SIGSTOP, thaw it with SIGCONT, or kill it outright, and domain recipes handle common cases such as shutting down every simulator. The core is a Swift framework: a thermal monitor that combines ProcessInfo.thermalState with Mach load statistics, a process enumerator built on libproc (proc_listpids, proc_pidinfo, proc_pidpath), a swarm aggregator, an anomaly detector, and a signal controller. The same core drives a SwiftUI MenuBarExtra app and a firebreak command-line tool. The direct-download build also reads CPU die temperatures from the hardware sensors through IOKit.

Key Features

• Menu bar extra with a live thermal badge and the culprit's CPU % when the breaker trips
• Process-tree aware: collapses child PIDs, .appex extensions, and container runtimes into their root app
• One-click freeze (SIGSTOP), thaw (SIGCONT), or kill (SIGKILL) across an entire process swarm
• Anomaly detection on thermal velocity, core saturation, and multi-process runaway
• Recovery recipes, such as shutting down every iOS Simulator at once
• Actionable notifications with Shutdown, Freeze, and Kill buttons
• Adaptive sampling: every 6 seconds when nominal, every 1.5 seconds on alert
• firebreak CLI with status, scan, trip, and cool commands; trip exits 1 when the breaker trips, for cron and CI
• Runs entirely on-device: no network access, no accounts, no analytics

Challenges & Solutions

Outcomes & Impact