Go Runtime Tuning and Profiling

Go is famous for working out of the box. At scale, knowing where the levers are pays back.

Why Go default works

Go runtime: garbage collector tuned for sub-ms pause; goroutine scheduler scales to many cores.

Defaults work for 95% of workloads.

Four runtime parameters

• GOMAXPROCS, CPU count override.
• GOGC, GC trigger frequency.
• GOMEMLIMIT, soft memory limit (1.19+).
• GODEBUG, runtime tracing flags.

pprof workflow

go tool pprof for CPU and heap profiles.

Workflow: capture; analyze; identify hot path; fix; verify.

Production profiling

Continuous profiler in production: Pyroscope, Polar Signals. Low overhead; always-on.

Replaces ‘capture profile during incident’ with ‘trends over weeks.’

Antipatterns

• GOMAXPROCS not set in containers. Go sees host CPU count; thrashing.
• No production profiling. Diagnose blind.
• GC tuning by guess. Defaults are usually right.

What to do this week

Three moves. (1) Apply this pattern to your slowest production endpoint. (2) Measure p99 before/after. (3) Document the win and ship the runbook so the team can reproduce.