英文:
How do you time a function in Go and return its runtime in milliseconds?
问题
如何在Go中计时一个函数并以毫秒为单位返回其运行时间？
英文:
How do you time a function in Go and return its runtime in milliseconds?
答案1
得分: 38
Go的defer使得这个变得简单。
在Go 1.x中，定义以下函数：
func trace(s string) (string, time.Time) {
log.Println("START:", s)
return s, time.Now()
}
func un(s string, startTime time.Time) {
endTime := time.Now()
log.Println(" END:", s, "ElapsedTime in seconds:", endTime.Sub(startTime))
}
之后，你会得到简洁的一行经过时间的日志信息：
func someFunction() {
defer un(trace("SOME_ARBITRARY_STRING_SO_YOU_CAN_KEEP_TRACK"))
//在这里做一些事情...
}
聪明的魔法是trace()在函数开始时被调用，但un()被延迟到最后。由于日志语句的存在，它并不是原子钟精确，但如果你需要更高的精确度，这种模式是Go的一个优势。
编辑：
这个答案最初使用了旧的time包API。这里只是为了历史价值而重现：
用于Go版本在2011年12月1日之前的周刊：
func trace(s string) (string, int64) {
log.Println("START:", s)
return s, time.Nanoseconds()
}
func un(s string, startTime int64) {
endTime := time.Nanoseconds()
log.Println(" END:", s, "ElapsedTime in seconds:", float32(endTime-startTime)/1E9)
}
英文:
Go's defer makes this trivial.
In Go 1.x, define the following functions:
func trace(s string) (string, time.Time) {
log.Println("START:", s)
return s, time.Now()
}
func un(s string, startTime time.Time) {
endTime := time.Now()
log.Println(" END:", s, "ElapsedTime in seconds:", endTime.Sub(startTime))
}
After that, you get Squeaky Clean one line elapsed time log messages:
func someFunction() {
defer un(trace("SOME_ARBITRARY_STRING_SO_YOU_CAN_KEEP_TRACK"))
//do a bunch of stuff here...
}
The clever magic is that the trace() is called at the beginning of the function, but the un() is deferred to the end. It's not atomic-clock accurate, due to the log statements, but if you need more accuracy, this kind of pattern is one of Go's marshmallowy good strengths.
EDIT:
This answer originally used legacy time package API. Reproduced here for historical value only:
For use w/ Go versions prior to 12-01-2011 weekly:
func trace(s string) (string, int64) {
log.Println("START:", s)
return s, time.Nanoseconds()
}
func un(s string, startTime int64) {
endTime := time.Nanoseconds()
log.Println(" END:", s, "ElapsedTime in seconds:", float32(endTime-startTime)/1E9)
}
答案2
得分: 31
使用Go testing包来对函数进行基准测试。例如，
package main
import (
"fmt"
"testing"
)
// 要进行基准测试的函数
func Function(n int) int64 {
n64 := int64(n)
return n64 * n64
}
func BenchmarkFunction(b *testing.B) {
n := 42
for i := 0; i < b.N; i++ {
_ = Function(n)
}
}
func main() {
br := testing.Benchmark(BenchmarkFunction)
fmt.Println(br)
}
输出：
500000000 4.22 ns/op
您还可以使用Go gotest命令来运行基准测试。
英文:
Use the Go testing package to benchmark the function. For example,
package main
import (
"fmt"
"testing"
)
// the function to be benchmarked
func Function(n int) int64 {
n64 := int64(n)
return n64 * n64
}
func BenchmarkFunction(b *testing.B) {
n := 42
for i := 0; i < b.N; i++ {
_ = Function(n)
}
}
func main() {
br := testing.Benchmark(BenchmarkFunction)
fmt.Println(br)
}
Output:
500000000 4.22 ns/op
You can also use the Go gotest command to run benchmarks.
答案3
得分: 17
另一种简单的方法可以是：
import (
"fmt"
"time"
)
start := time.Now()
// 进行一些计算
elapsed := time.Since(start)
fmt.Println(elapsed)
这将输出类似于 359.684612ms 的内容。
英文:
Another easy way can be:
import (
"fmt"
"time"
)
start := time.Now()
// some computation
elapsed := time.Since(start)
fmt.Println(elapsed)
which will output something like 359.684612ms
答案4
得分: 12
也许你也可以使用一个持续时间（经过的时间）来实现这个...看起来更好一些。
func trace(s string) (string, time.Time) {
log.Printf("跟踪开始：%s\n", s)
return s, time.Now()
}
func un(s string, startTime time.Time) {
elapsed := time.Since(startTime)
log.Printf("跟踪结束：%s，经过时间 %f 秒\n", s, elapsed.Seconds())
}
英文:
Perhaps you can also use a Duration (elapsed) for this...looks a little bit nicer.
func trace(s string) (string, time.Time) {
log.Printf("trace start: %s\n", s)
return s, time.Now()
}
func un(s string, startTime time.Time) {
elapsed := time.Since(startTime)
log.Printf("trace end: %s, elapsed %f secs\n", s, elapsed.Seconds())
}
答案5
得分: 1
有关时间戳和定时器的时间包有几个选项。请参阅此处的文档：http://golang.org/pkg/time/
英文:
There are several options for timestamping and timers in the time package. See the documentation here: http://golang.org/pkg/time/
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