我可以无痛使用多少goroutines?例如,维基百科说,在Erlang中,可以创建2000万个进程,而不会降低性能.
Update:我只有investigated in goroutines performance点,结果是这样的:
- 看起来goroutine的生存期比计算sqrt()要长1000倍(对于我来说大约是45µs),唯一的限制是内存
- Goroutine成本为4-4.5KB
我可以无痛使用多少goroutines?例如,维基百科说,在Erlang中,可以创建2000万个进程,而不会降低性能.
Update:我只有investigated in goroutines performance点,结果是这样的:
如果Goroutine被阻止,除了以下情况外不会涉及任何成本:
成本(就内存和实际开始执行goroutine的平均时间而言)为:
Go 1.6.2 (April 2016)
32-bit x86 CPU (A10-7850K 4GHz)
| Number of goroutines: 100000
| Per goroutine:
| Memory: 4536.84 bytes
| Time: 1.634248 µs
64-bit x86 CPU (A10-7850K 4GHz)
| Number of goroutines: 100000
| Per goroutine:
| Memory: 4707.92 bytes
| Time: 1.842097 µs
Go release.r60.3 (December 2011)
32-bit x86 CPU (1.6 GHz)
| Number of goroutines: 100000
| Per goroutine:
| Memory: 4243.45 bytes
| Time: 5.815950 µs
在安装了4 GB内存的计算机上,这将Goroutines的最大数量限制为略低于100万.
源代码(如果您已经理解上面打印的数字,则无需阅读本文):
package main
import (
"flag"
"fmt"
"os"
"runtime"
"time"
)
var n = flag.Int("n", 1e5, "Number of goroutines to create")
var ch = make(chan byte)
var counter = 0
func f() {
counter++
<-ch // Block this goroutine
}
func main() {
flag.Parse()
if *n <= 0 {
fmt.Fprintf(os.Stderr, "invalid number of goroutines")
os.Exit(1)
}
// Limit the number of spare OS threads to just 1
runtime.GOMAXPROCS(1)
// Make a copy of MemStats
var m0 runtime.MemStats
runtime.ReadMemStats(&m0)
t0 := time.Now().UnixNano()
for i := 0; i < *n; i++ {
go f()
}
runtime.Gosched()
t1 := time.Now().UnixNano()
runtime.GC()
// Make a copy of MemStats
var m1 runtime.MemStats
runtime.ReadMemStats(&m1)
if counter != *n {
fmt.Fprintf(os.Stderr, "failed to begin execution of all goroutines")
os.Exit(1)
}
fmt.Printf("Number of goroutines: %d\n", *n)
fmt.Printf("Per goroutine:\n")
fmt.Printf(" Memory: %.2f bytes\n", float64(m1.Sys-m0.Sys)/float64(*n))
fmt.Printf(" Time: %f µs\n", float64(t1-t0)/float64(*n)/1e3)
}