How Android works
Memory, lifecycle & power
Why Android kills apps on purpose, and how it rations the battery.
5 pages60 min5 interactive8600 words
- 01Process importance and the OOM killerAndroid kills processes on purpose. The oom_adj score, the importance tiers, lmkd and PSI, and why clearing your recents saves less battery than it looks.intermediate13 mininteractive
- 02Memory accountingRSS, PSS, USS, private dirty and the shared Zygote pages: why the number in dumpsys meminfo is smaller than the sum of what the process mapped, and which number actually matters.nerd12 mininteractive
- 03Doze and App StandbyTwo different throttles for two different situations: Doze when the device is idle, App Standby when the app is unused. How they interact, why maintenance windows widen, and what still gets through.intermediate12 mininteractive
- 04Background execution limitsThe decade-long campaign to stop apps running when nobody is looking: background service limits, broadcast restrictions, foreground service types, and the launch restrictions that followed.intermediate12 mininteractive
- 05Battery and thermalHow Android attributes power to apps, why a hot phone throttles before the battery dies, and what Adaptive Battery actually predicts.nerd11 mininteractive
Test yourself
Test yourself: Memory, lifecycle & power
What happens to the maintenance windows the longer a device stays in Doze?