Memory Leak

Prerequisite: This is Part 10 of the System Design Masterclass. Previous parts built the architecture — this part teaches you how to see inside a running system and diagnose production performance issues. Answer-first: Go’s built-in pprof profiler provides CPU sampling, heap allocation analysis, goroutine stack inspection, and blocking profiler — all available as HTTP endpoints in running production services with minimal overhead. Heap diff between two snapshots is the fastest way to identify memory leaks. ...

Answer-first: Goroutine leaks block indefinitely and hold GC roots, leading to slow, silent memory exhaustion and pod restarts. Pinpoint leaks by comparing pprof profile snapshots (specifically goroutineleak in Go 1.26), write deterministic tests with Go 1.24’s synctest, and set automated telemetry alerts on active goroutine counts. What You’ll Learn That AI Won’t Tell You Writing automated test cases that detect goroutine leaks before deploying. Analyzing production runtime stack traces to locate orphaned channels. A Kubernetes pod abruptly restarts with exit code 137. The memory metrics dashboard shows a slow, perfectly linear staircase pattern stretching over three days. There are no panic logs in stdout, no database errors, and no abnormal CPU spikes. Just a slow, silent OOM (Out Of Memory) death. ...