defer性能测试数据大概相差4-5倍的样子，测试环境 go 1.8

package test

import (
    "sync"
    "testing"
)

var m sync.Mutex

func call() {
    m.Lock()
    m.Unlock()
}

func deferCall() {
    m.Lock()
    defer m.Unlock()
}

func BenchmarkCall(b *testing.B) {
    for i := 0; i < b.N; i++ {
        call()
    }
}

func BenchmarkDeferCall(b *testing.B) {
    for i := 0; i < b.N; i++ {
        deferCall()
    }
}

/*
BenchmarkCall-8         100000000           22.2 ns/op
BenchmarkDeferCall-8    10000000           118 ns/op
PASS
ok      defer_perf  3.557s
*/

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