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callcount

sync.Mutex.Lock

standard library

The 14th most-called standard-library method by production calls. Called 1,870 times across 201 modules; 1,486 of those run outside tests and generated code.

6% in production calls vs 2026-06-sample (1,401 → 1,486)

All of sync → Docs on pkg.go.dev ↗

prod calls
1,486
non-test, non-generated
all calls
1,870
total callsites
modules
201
distinct callers
in loop
34%
of prod calls
in tests
15%
281 calls
resolved
97%
to a known target

resolution mix

How each call resolves

How each call was attributed. Only resolved kinds, where the target function is known, count toward the ranking. Interface dispatch and unresolved receivers are reported separately and never guessed. Read the taxonomy →

  • Concrete method78%A method on a value whose type is known exactly.
  • Embedded method19%Reached through an embedded type.
  • Unresolved3%Receiver typed by a dependency outside the crawl.

estimate

Experimental

Estimated relative cost

Roughly 0.03× the estimated relative cost of fmt.Sprintf . Benchmarked at 13.6 ns/op × 1,486 production calls, normalized so fmt.Sprintf = 1.0.

This is not dollars and not a verdict. Per-op time depends heavily on inputs (argument sizes, contention, patterns), the benchmark ran on a single machine (darwin/arm64, go1.22.5), and static call counts are not runtime frequency. How this is estimated →

who calls this

Notable callers

Production calls into Mutex.Lock from notable Go projects. Open one on the map to see what else it hammers.

where it's called

Callsites in the wild

6 representative callsites of 1,870, prioritizing in-loop and non-test usage. We link to source, never display it.

Mutex.Lock · 6 of 1,870 callsites

top callers

The modules that reach for it

The modules that call Mutex.Lock most in this snapshot.

  • k8s.io/apimachinery56830%
  • github.com/spf13/cobra25614%
  • github.com/prometheus/client_golang1247%

siblings

More from sync

The other most-called members in this package. See all →