mirror of https://github.com/golang/go.git
e6ad619ad6
The first biggest offender was crypto/des.init at ~1%. It's cryptographically broken and the init function is relatively expensive, which is unfortunate as both crypto/tls and crypto/x509 (and by extension, cmd/go) import it. Hide the work behind sync.Once. The second biggest offender was flag.sortFlags at just under 1%, used by the Visit flagset methods. It allocated two slices, which made a difference as cmd/go iterates over multiple flagsets during init. Use a single slice with a direct sort.Interface implementation. Another big offender is initializing global maps. Reducing this work in cmd/go/internal/imports and net/textproto gives us close to another whole 1% in saved work. The former can use map literals, and the latter can hide the work behind sync.Once. Finally, compress/flate used newHuffmanBitWriter as part of init, which allocates many objects and slices. Yet it only used one of the slice fields. Allocating just that slice saves a surprising ~0.3%, since we generated a lot of unnecessary garbage. All in all, these little pieces amount to just over 3% saved CPU time. name old time/op new time/op delta ExecGoEnv-8 3.61ms ± 1% 3.50ms ± 0% -3.02% (p=0.000 n=10+10) Updates #26775. Updates #29382. Change-Id: I915416e88a874c63235ba512617c8aef35c0ca8b Reviewed-on: https://go-review.googlesource.com/c/go/+/166459 Run-TryBot: Daniel Martí <mvdan@mvdan.cc> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org> |
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