时间。睡眠会阻止goroutine吗？

我有下一个代码：

par.go

package main

import (
    "runtime";
    "time"
)

func main() {
    runtime.GOMAXPROCS(4)
    ch := make(chan int)
    n := 1
    for i := 0; i < n; i++ {
        go func() {
            time.Sleep(60 * time.Second)
            ch <- 1
        }();
    }
    for i := 0; i < n; i++ {
        <-ch
    }
}

然后，确认此进程中有多少线程：

$ ps -ef | grep par
shubunt+  3670 32131  0 12:35 pts/0    00:00:00 ./par
$ cat /proc/3670/status | grep -i threads
Threads:        5

你可以看到有5个线程

如果我在代码中更改

n

的值，则情况如下：

n := 100, Threads is 8
n := 10000, Threads is 9
n := 100000, Threads is 9
n := 1000000, Threads is 9
n := 2000000, Threads is 10

我知道，go调度器遵循

MPG

模型，这里

p=4

，所以

M=4

，

M

是

1:1

和

KSE

（内核线程）。如果任何goroutine处于任何阻塞状态，

P

将从当前的

M

中分离，如果找不到，则查找空闲的

M

或新的

M

所以，我的问题是：

time.Sleep

真的阻止了goroutine吗？如果不是，当我将

n

的值从

1

增加到

2000000

时，为什么会出现新线程？如果是的，那里有

60秒

，为什么要新建一点

M

，我希望那里有很多新线程

更新：

package main

import (
    "io/ioutil"
    "os"
    "runtime"
    "strconv"
)

func main() {
    runtime.GOMAXPROCS(2)
    data := make([]byte, 128*1024*1024)
    for i := 0; i < 200; i++ {
        go func(n int) {
            for {
                err := ioutil.WriteFile("testxxx"+strconv.Itoa(n), []byte(data), os.ModePerm)
                if err != nil {
                    println(err)
                    break
                }
            }
        }(i)
    }
    select {}
}

从中添加另一个示例

测试。转到：

package main

import (
    "io/ioutil"
    "os"
    "runtime"
    "strconv"
)

func main() {
    runtime.GOMAXPROCS(2)
    data := make([]byte, 128*1024*1024)
    for i := 0; i < 200; i++ {
        go func(n int) {
            for {
                err := ioutil.WriteFile("testxxx"+strconv.Itoa(n), []byte(data), os.ModePerm)
                if err != nil {
                    println(err)
                    break
                }
            }
        }(i)
    }
    select {}
}

主程序包
进口(
“io/ioutil”
“操作系统”
“运行时”
“strconv”
)
func main（）{
runtime.GOMAXPROCS（2）
数据：=生成（[]字节，128*1024*1024）
对于i:=0；i<200；i++{
go func（n int）{
为了{
err:=ioutil.WriteFile（“testxxx”+strconv.Itoa（n），[]字节（数据），os.ModePerm）
如果错误！=零{
println（err）
打破
}
}
}(一)
}
选择{}
}

如果不使用

Sleep

，请使用real IO，我的机器上的线程数将为

202

所以，我的问题也与上面两个例子的不同有关，我什么时候应该担心调度器为我生成太多的内核线程

[一] 是时候了。睡眠真的阻碍了goroutine吗

对

但是goroutine实际上是如何调度到线程的是a）复杂的，b）在每个版本中都不同，c）在不同的体系结构中可能不同，d）语言没有指定。而“MPG模型”是一个精确的模型，如果调度器是如何工作的，那么它只是一个模型

如果调度程序确定10个线程足以不运行200000个goroutines，因为它们都是

时间。Sleep

ing，那么10个线程就足够了

基本上，在围棋中没有什么需要担心或思考的东西（与其他语言形成鲜明对比，在其他语言中，对这些特性必须非常小心）。“阻塞”只是意味着下一条语句无法立即执行，因为实际语句尚未完成。如果原因从时间到睡眠什么都不做，除了等待、等待形成RAM、等待磁盘或等待网络数据，这种情况可能会发生过多。以相同的方式处理所有这些将简化调度程序，但使其成为一个糟糕的调度程序。所以，不，时间。睡眠并不会阻止我们的狂欢。问题是“block goroutine”并没有明确的含义。它不需要被定义为没有什么有趣的事情要知道

更新：

[W] 什么时候我应该担心调度器为我生成太多的内核线程

从来没有

有两种不同的场景：a）编写正常、合理的生产代码和B）编写手工编写的代码，这些代码经过精心设计，可以创建大量线程，这些线程都在磁盘IO中等待完成。当然，您可以故意欺骗调度程序和操作系统，并想出一个病态的程序来创建太多的线程（调度程序可能被欺骗的这个问题是问题4056中的地址），但这并不需要担心。只是不要故意做傻事

---

有很多方法可以欺骗你的电脑。编写快速代码是一种方法。种族检测器有助于识别他们。在写之前担心种族状况是一件好事（就像这样）。可能会创建太多线程，您可以向操作系统询问线程数。在不太可能的情况下，有太多：修复它。但这不太可能。这有点像OOM错误：编写OOM的代码非常简单，但在编写代码时无需经常担心OOM。如果您的经验表明您需要重新设计OOM，但您并没有通过担心OOM以及您需要了解的OOM、如何防止OOM以及如何处理OOM来启动任何琐碎的项目。除非你已经知道你的数据占用了很多内存。此处相同：如果您知道您的代码将执行大量并发磁盘IO，并且这是域固有的，那么您可能会担心这一点，并在代码中处理这一点，但每种语言的技术都是相同的。

总结我对这个问题的最终理解，以防有人感兴趣：

对于

time.Sleep

，如果我设置启动20个goroutines，接下来是

delve

的结果：

 ./dlv attach 2070
 Type 'help' for list of commands.
 (dlv) threads
 * Thread 2070 at 0x44d003 /usr/lib/go-1.12/src/runtime/sys_linux_amd64.s:536 runtime.futex
   Thread 2071 at 0x44d003 /usr/lib/go-1.12/src/runtime/sys_linux_amd64.s:536 runtime.futex
   Thread 2072 at 0x44d003 /usr/lib/go-1.12/src/runtime/sys_linux_amd64.s:536 runtime.futex
   Thread 2092 at 0x44d003 /usr/lib/go-1.12/src/runtime/sys_linux_amd64.s:536 runtime.futex
   Thread 2093 at 0x44d003 /usr/lib/go-1.12/src/runtime/sys_linux_amd64.s:536 runtime.futex
 (dlv) grs
   Goroutine 1 - User: /home/shubuntu1/gotrial/new/par.go:19 main.main (0x452686)
   Goroutine 2 - User: /usr/lib/go-1.12/src/runtime/proc.go:302    runtime.gopark (0x425f3f)
   Goroutine 3 - User: /usr/lib/go-1.12/src/runtime/proc.go:302 runtime.gopark (0x425f3f)
   Goroutine 4 - User: /usr/lib/go-1.12/src/runtime/proc.go:307 time.Sleep (0x43cc69)
   Goroutine 5 - User: /usr/lib/go-1.12/src/runtime/proc.go:307 time.Sleep (0x43cc69)
   Goroutine 6 - User: /usr/lib/go-1.12/src/runtime/proc.go:307 time.Sleep (0x43cc69)
   Goroutine 7 - User: /usr/lib/go-1.12/src/runtime/proc.go:307 time.Sleep (0x43cc69)
   Goroutine 8 - User: /usr/lib/go-1.12/src/runtime/proc.go:307 time.Sleep (0x43cc69)
   Goroutine 9 - User: /usr/lib/go-1.12/src/runtime/proc.go:307 time.Sleep (0x43cc69)
   Goroutine 10 - User: /usr/lib/go-1.12/src/runtime/proc.go:307 time.Sleep (0x43cc69)
   Goroutine 11 - User: /usr/lib/go-1.12/src/runtime/proc.go:307 time.Sleep (0x43cc69)
   Goroutine 12 - User: /usr/lib/go-1.12/src/runtime/proc.go:307 time.Sleep (0x43cc69)
   Goroutine 13 - User: /usr/lib/go-1.12/src/runtime/proc.go:307 time.Sleep (0x43cc69)
   Goroutine 14 - User: /usr/lib/go-1.12/src/runtime/proc.go:307 time.Sleep (0x43cc69)
   Goroutine 15 - User: /usr/lib/go-1.12/src/runtime/proc.go:307 time.Sleep (0x43cc69)
   Goroutine 16 - User: /usr/lib/go-1.12/src/runtime/proc.go:307 time.Sleep (0x43cc69)
   Goroutine 17 - User: /usr/lib/go-1.12/src/runtime/proc.go:307 time.Sleep (0x43cc69)
   Goroutine 18 - User: /usr/lib/go-1.12/src/runtime/proc.go:307 time.Sleep (0x43cc69)
   Goroutine 19 - User: /usr/lib/go-1.12/src/runtime/proc.go:307 time.Sleep (0x43cc69)
   Goroutine 20 - User: /usr/lib/go-1.12/src/runtime/proc.go:307 time.Sleep (0x43cc69)
   Goroutine 21 - User: /usr/lib/go-1.12/src/runtime/proc.go:307 time.Sleep (0x43cc69)
   Goroutine 22 - User: /usr/lib/go-1.12/src/runtime/proc.go:307 time.Sleep (0x43cc69)
   Goroutine 23 - User: /usr/lib/go-1.12/src/runtime/proc.go:307 time.Sleep (0x43cc69)
 * Goroutine 24 - User: /usr/lib/go-1.12/src/runtime/lock_futex.go:228 runtime.notetsleepg (0x409064)
 [24 goroutines]

 ./dlv attach 2455
 Type 'help' for list of commands.
 (dlv) threads
 * Thread 2455 at 0x460e90 /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall
   Thread 2456 at 0x4530f3 /usr/lib/go-1.12/src/runtime/sys_linux_amd64.s:536 runtime.futex
   Thread 2457 at 0x460f0a /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:53 syscall.Syscall6
   Thread 2458 at 0x460e90 /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall
   Thread 2459 at 0x460e90 /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall
   Thread 2460 at 0x460e90 /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall
   Thread 2461 at 0x460e90 /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall
   Thread 2462 at 0x460e90 /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall
   Thread 2463 at 0x460e90 /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall
   Thread 2464 at 0x460e90 /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall
   Thread 2465 at 0x460e90 /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall
   Thread 2466 at 0x460e90 /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall
   Thread 2468 at 0x460e90 /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall
   Thread 2469 at 0x460e90 /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall
   Thread 2470 at 0x460e90 /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall
   Thread 2471 at 0x460e90 /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall
   Thread 2472 at 0x460f0a /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:53 syscall.Syscall6
   Thread 2473 at 0x460f0a /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:53 syscall.Syscall6
   Thread 2474 at 0x460e90 /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall
   Thread 2475 at 0x460f0a /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:53 syscall.Syscall6
   Thread 2476 at 0x460f0a /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:53 syscall.Syscall6
   Thread 2477 at 0x4530f3 /usr/lib/go-1.12/src/runtime/sys_linux_amd64.s:536 runtime.futex
 (dlv) grs
   Goroutine 1 - User: /home/shubuntu1/gotrial/newnew/test.go:24 main.main (0x4754b0)
   Goroutine 2 - User: /usr/lib/go-1.12/src/runtime/proc.go:302 runtime.gopark (0x429d9f)
   Goroutine 3 - User: /usr/lib/go-1.12/src/runtime/proc.go:302 runtime.gopark (0x429d9f)
   Goroutine 4 - User: /usr/lib/go-1.12/src/runtime/proc.go:302 runtime.gopark (0x429d9f)
   Goroutine 5 - User: /usr/lib/go-1.12/src/runtime/proc.go:302 runtime.gopark (0x429d9f)
   Goroutine 6 - User: /usr/lib/go-1.12/src/runtime/proc.go:302 runtime.gopark (0x429d9f)
   Goroutine 7 - User: /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:53 syscall.Syscall6 (0x460f0a) (thread 2457)
   Goroutine 8 - User: /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:53 syscall.Syscall6 (0x460f0a) (thread 2476)
   Goroutine 9 - User: /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall (0x460e90) (thread 2461)
   Goroutine 10 - User: /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:53 syscall.Syscall6 (0x460f0a) (thread 2473)
   Goroutine 11 - User: /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall (0x460e90) (thread 2468)
   Goroutine 12 - User: /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall (0x460e90) (thread 2469)
 * Goroutine 13 - User: /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall (0x460e90) (thread 2455)
   Goroutine 14 - User: /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall (0x460e90) (thread 2459)
   Goroutine 15 - User: /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall (0x460e90) (thread 2460)
   Goroutine 16 - User: /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall (0x460e90) (thread 2471)
   Goroutine 17 - User: /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall (0x460e90) (thread 2464)
   Goroutine 18 - User: /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall (0x460e90) (thread 2462)
   Goroutine 19 - User: /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall (0x460e90) (thread 2466)
   Goroutine 20 - User: /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall (0x460e90) (thread 2474)
   Goroutine 21 - User: /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall (0x460e90) (thread 2470)
   Goroutine 22 - User: /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall (0x460e90) (thread 2463)
   Goroutine 23 - User: /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:53 syscall.Syscall6 (0x460f0a) (thread 2472)
   Goroutine 24 - User: /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall (0x460e90) (thread 2458)
   Goroutine 25 - User: /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:53 syscall.Syscall6 (0x460f0a) (thread 2475)
   Goroutine 26 - User: /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall (0x460e90) (thread 2465)
 [26 goroutines]
 (dlv)

您可以看到，在

时间内有许多goroutine.Sleep

而只有一些线程，这些线程正在运行

runtime.futex

此外，我们还可以知道，

golang sleep

将涉及一个

lock

，因此这可能是一些额外线程启动的原因，但是锁很快就被释放了，因此那里没有那么多线程，许多goroutine仍然可以重用同一个线程

对于

ioutil.WriteFile

，如果我设置为启动20个goroutines，接下来是

delve

的结果：

 ./dlv attach 2070
 Type 'help' for list of commands.
 (dlv) threads
 * Thread 2070 at 0x44d003 /usr/lib/go-1.12/src/runtime/sys_linux_amd64.s:536 runtime.futex
   Thread 2071 at 0x44d003 /usr/lib/go-1.12/src/runtime/sys_linux_amd64.s:536 runtime.futex
   Thread 2072 at 0x44d003 /usr/lib/go-1.12/src/runtime/sys_linux_amd64.s:536 runtime.futex
   Thread 2092 at 0x44d003 /usr/lib/go-1.12/src/runtime/sys_linux_amd64.s:536 runtime.futex
   Thread 2093 at 0x44d003 /usr/lib/go-1.12/src/runtime/sys_linux_amd64.s:536 runtime.futex
 (dlv) grs
   Goroutine 1 - User: /home/shubuntu1/gotrial/new/par.go:19 main.main (0x452686)
   Goroutine 2 - User: /usr/lib/go-1.12/src/runtime/proc.go:302    runtime.gopark (0x425f3f)
   Goroutine 3 - User: /usr/lib/go-1.12/src/runtime/proc.go:302 runtime.gopark (0x425f3f)
   Goroutine 4 - User: /usr/lib/go-1.12/src/runtime/proc.go:307 time.Sleep (0x43cc69)
   Goroutine 5 - User: /usr/lib/go-1.12/src/runtime/proc.go:307 time.Sleep (0x43cc69)
   Goroutine 6 - User: /usr/lib/go-1.12/src/runtime/proc.go:307 time.Sleep (0x43cc69)
   Goroutine 7 - User: /usr/lib/go-1.12/src/runtime/proc.go:307 time.Sleep (0x43cc69)
   Goroutine 8 - User: /usr/lib/go-1.12/src/runtime/proc.go:307 time.Sleep (0x43cc69)
   Goroutine 9 - User: /usr/lib/go-1.12/src/runtime/proc.go:307 time.Sleep (0x43cc69)
   Goroutine 10 - User: /usr/lib/go-1.12/src/runtime/proc.go:307 time.Sleep (0x43cc69)
   Goroutine 11 - User: /usr/lib/go-1.12/src/runtime/proc.go:307 time.Sleep (0x43cc69)
   Goroutine 12 - User: /usr/lib/go-1.12/src/runtime/proc.go:307 time.Sleep (0x43cc69)
   Goroutine 13 - User: /usr/lib/go-1.12/src/runtime/proc.go:307 time.Sleep (0x43cc69)
   Goroutine 14 - User: /usr/lib/go-1.12/src/runtime/proc.go:307 time.Sleep (0x43cc69)
   Goroutine 15 - User: /usr/lib/go-1.12/src/runtime/proc.go:307 time.Sleep (0x43cc69)
   Goroutine 16 - User: /usr/lib/go-1.12/src/runtime/proc.go:307 time.Sleep (0x43cc69)
   Goroutine 17 - User: /usr/lib/go-1.12/src/runtime/proc.go:307 time.Sleep (0x43cc69)
   Goroutine 18 - User: /usr/lib/go-1.12/src/runtime/proc.go:307 time.Sleep (0x43cc69)
   Goroutine 19 - User: /usr/lib/go-1.12/src/runtime/proc.go:307 time.Sleep (0x43cc69)
   Goroutine 20 - User: /usr/lib/go-1.12/src/runtime/proc.go:307 time.Sleep (0x43cc69)
   Goroutine 21 - User: /usr/lib/go-1.12/src/runtime/proc.go:307 time.Sleep (0x43cc69)
   Goroutine 22 - User: /usr/lib/go-1.12/src/runtime/proc.go:307 time.Sleep (0x43cc69)
   Goroutine 23 - User: /usr/lib/go-1.12/src/runtime/proc.go:307 time.Sleep (0x43cc69)
 * Goroutine 24 - User: /usr/lib/go-1.12/src/runtime/lock_futex.go:228 runtime.notetsleepg (0x409064)
 [24 goroutines]

 ./dlv attach 2455
 Type 'help' for list of commands.
 (dlv) threads
 * Thread 2455 at 0x460e90 /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall
   Thread 2456 at 0x4530f3 /usr/lib/go-1.12/src/runtime/sys_linux_amd64.s:536 runtime.futex
   Thread 2457 at 0x460f0a /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:53 syscall.Syscall6
   Thread 2458 at 0x460e90 /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall
   Thread 2459 at 0x460e90 /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall
   Thread 2460 at 0x460e90 /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall
   Thread 2461 at 0x460e90 /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall
   Thread 2462 at 0x460e90 /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall
   Thread 2463 at 0x460e90 /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall
   Thread 2464 at 0x460e90 /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall
   Thread 2465 at 0x460e90 /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall
   Thread 2466 at 0x460e90 /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall
   Thread 2468 at 0x460e90 /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall
   Thread 2469 at 0x460e90 /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall
   Thread 2470 at 0x460e90 /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall
   Thread 2471 at 0x460e90 /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall
   Thread 2472 at 0x460f0a /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:53 syscall.Syscall6
   Thread 2473 at 0x460f0a /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:53 syscall.Syscall6
   Thread 2474 at 0x460e90 /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall
   Thread 2475 at 0x460f0a /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:53 syscall.Syscall6
   Thread 2476 at 0x460f0a /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:53 syscall.Syscall6
   Thread 2477 at 0x4530f3 /usr/lib/go-1.12/src/runtime/sys_linux_amd64.s:536 runtime.futex
 (dlv) grs
   Goroutine 1 - User: /home/shubuntu1/gotrial/newnew/test.go:24 main.main (0x4754b0)
   Goroutine 2 - User: /usr/lib/go-1.12/src/runtime/proc.go:302 runtime.gopark (0x429d9f)
   Goroutine 3 - User: /usr/lib/go-1.12/src/runtime/proc.go:302 runtime.gopark (0x429d9f)
   Goroutine 4 - User: /usr/lib/go-1.12/src/runtime/proc.go:302 runtime.gopark (0x429d9f)
   Goroutine 5 - User: /usr/lib/go-1.12/src/runtime/proc.go:302 runtime.gopark (0x429d9f)
   Goroutine 6 - User: /usr/lib/go-1.12/src/runtime/proc.go:302 runtime.gopark (0x429d9f)
   Goroutine 7 - User: /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:53 syscall.Syscall6 (0x460f0a) (thread 2457)
   Goroutine 8 - User: /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:53 syscall.Syscall6 (0x460f0a) (thread 2476)
   Goroutine 9 - User: /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall (0x460e90) (thread 2461)
   Goroutine 10 - User: /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:53 syscall.Syscall6 (0x460f0a) (thread 2473)
   Goroutine 11 - User: /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall (0x460e90) (thread 2468)
   Goroutine 12 - User: /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall (0x460e90) (thread 2469)
 * Goroutine 13 - User: /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall (0x460e90) (thread 2455)
   Goroutine 14 - User: /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall (0x460e90) (thread 2459)
   Goroutine 15 - User: /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall (0x460e90) (thread 2460)
   Goroutine 16 - User: /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall (0x460e90) (thread 2471)
   Goroutine 17 - User: /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall (0x460e90) (thread 2464)
   Goroutine 18 - User: /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall (0x460e90) (thread 2462)
   Goroutine 19 - User: /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall (0x460e90) (thread 2466)
   Goroutine 20 - User: /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall (0x460e90) (thread 2474)
   Goroutine 21 - User: /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall (0x460e90) (thread 2470)
   Goroutine 22 - User: /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall (0x460e90) (thread 2463)
   Goroutine 23 - User: /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:53 syscall.Syscall6 (0x460f0a) (thread 2472)
   Goroutine 24 - User: /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall (0x460e90) (thread 2458)
   Goroutine 25 - User: /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:53 syscall.Syscall6 (0x460f0a) (thread 2475)
   Goroutine 26 - User: /usr/lib/go-1.12/src/syscall/asm_linux_amd64.s:27 syscall.Syscall (0x460e90) (thread 2465)
 [26 goroutines]
 (dlv)

您可以看到，在

syscall

的过程中有许多goroutine，而在

syscall

中也有许多线程，不像

runtime.futex中的
sleep
那样只涉及锁。
ioutil
涉及实块系统调用。这是因为epoll不适用于linux上的常规文件，所以不像network io那样具有网络轮询器句柄阻塞接口和非阻塞低级系统调用，请参阅

所以，我想如果我们不能承受太多的线程