golang 运行时：无法创建新的 OS 线程（已经有 2049；errno=12）

Question

我在 MacOs 上创建了很多 goroutine，程序执行时出现错误。

goRoutineId = 3710, i = 3683, len(chan) = 2049
runtime: failed to create new OS thread (have 2049 already; errno=12)
fatal error: runtime.newosproc

所以我想知道 "failed to create new OS thread" 是什么意思，这是操作系统的限制，只是 golang 没有能力创建更多的 goroutine？谢谢你帮助我。

Answer 1

这是OS的限制。我假设您使用的是 linux.

根据the source of go，它正在调用 clone 系统调用

ret := clone(cloneFlags, stk, unsafe.Pointer(mp), unsafe.Pointer(mp.g0), unsafe.Pointer(funcPC(mstart)))
sigprocmask(_SIG_SETMASK, &oset, nil)

if ret < 0 {
    print("runtime: failed to create new OS thread (have ", mcount(), " already; errno=", -ret, ")\n")
    if ret == -_EAGAIN {
        println("runtime: may need to increase max user processes (ulimit -u)")
    }
    throw("newosproc")
}

来自 manpage of clone(2), when the errno=12, the error reason is out of memory

ENOMEM Cannot allocate sufficient memory to allocate a task structure
              for the child, or to copy those parts of the caller's context
              that need to be copied.

golang 运行时：无法创建新的 OS 线程（已经有 2049；errno=12）

golang runtime: failed to create new OS thread (have 2049 already; errno=12)

go

goroutine