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callcount

regexp.MustCompile

standard library

The 17th most-called standard-library function by production calls. Called 1,740 times across 224 modules; 1,311 of those run outside tests and generated code.

5% in production calls vs 2026-06-sample (1,380 → 1,311)

All of regexp → Docs on pkg.go.dev ↗

prod calls
1,311
non-test, non-generated
all calls
1,740
total callsites
modules
224
distinct callers
in loop
5%
of prod calls
in tests
18%
308 calls
resolved
100%
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 →

  • Package function100%A direct call to an exported package function, resolved by type.

estimate

Experimental

Estimated relative cost

Roughly 17× the estimated relative cost of fmt.Sprintf . Benchmarked at 8240 ns/op × 1,311 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 MustCompile 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 1,740, prioritizing in-loop and non-test usage. We link to source, never display it.

MustCompile · 6 of 1,740 callsites

top callers

The modules that reach for it

The modules that call MustCompile most in this snapshot.

  • github.com/stretchr/testify49829%
  • github.com/gorilla/mux24714%
  • github.com/docker/docker1509%

siblings

More from regexp

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