Benchmarks
The full pipeline — turn a .env file into a populated config struct —
against six popular libraries, measured at three config sizes: small (5
keys), medium (30 keys) and large (120 keys). Every row does the same
end-to-end work on the same config; env-only decoders are paired with godotenv
to read the file (the usual real-world combo). Correctness is asserted before
timing.
goversion: 1.26.2 goos: darwin goarch: arm64 cpu: Apple M4 Pro -count=5 (medians)
Small — 5 keys
| Library | ns/op | B/op | allocs/op | vs oneenv |
|---|---|---|---|---|
| oneenv | 621 | 752 | 17 | 1.0× |
sethvargo/go-envconfig |
1,803 | 839 | 32 | 2.9× |
joeshaw/envdecode |
2,383 | 980 | 42 | 3.8× |
ilyakaznacheev/cleanenv |
3,623 | 3,244 | 71 | 5.8× |
kelseyhightower/envconfig |
3,647 | 2,552 | 88 | 5.9× |
spf13/viper |
7,357 | 12,120 | 124 | 11.8× |
caarlos0/env v11 |
7,660 | 15,378 | 141 | 12.3× |
Medium — 30 keys
| Library | ns/op | B/op | allocs/op | vs oneenv |
|---|---|---|---|---|
| oneenv | 4,091 | 5,528 | 74 | 1.0× |
sethvargo/go-envconfig |
11,591 | 7,115 | 164 | 2.8× |
joeshaw/envdecode |
15,374 | 7,919 | 224 | 3.8× |
caarlos0/env v11 |
20,565 | 26,561 | 330 | 5.0× |
kelseyhightower/envconfig |
22,000 | 19,300 | 495 | 5.4× |
ilyakaznacheev/cleanenv |
22,017 | 18,329 | 380 | 5.4× |
spf13/viper |
45,583 | 52,423 | 568 | 11.1× |
Large — 120 keys
| Library | ns/op | B/op | allocs/op | vs oneenv |
|---|---|---|---|---|
| oneenv | 16,533 | 22,488 | 258 | 1.0× |
sethvargo/go-envconfig |
46,582 | 29,698 | 618 | 2.8× |
joeshaw/envdecode |
60,306 | 32,951 | 858 | 3.6× |
caarlos0/env v11 |
65,754 | 66,251 | 968 | 4.0× |
ilyakaznacheev/cleanenv |
85,087 | 75,138 | 1,466 | 5.1× |
kelseyhightower/envconfig |
91,126 | 59,966 | 1,939 | 5.5× |
spf13/viper |
231,347 | 199,626 | 2,035 | 14.0× |
oneenv is the fastest and lightest of the group at every size — 2.8–14.0×
faster with the fewest allocations (up to 20× less memory than caarlos0
at small, ~9× less than viper at large) — because it parses and decodes in a
single pass over a struct schema that is compiled once and cached. Reproduce:
cd internal/bench && go test -bench . -benchmem -count=5
The comparison lives in its own module, so the root package stays dependency-free.