duanqiongchong0354
2018-04-20 11:15
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Go是否具有等效的“无限调用堆栈”?

I'm a newbie to Go, coming from Node.JS.

In Node, if I run this:

function run(tick = 0) {
  if (tick < 1000000) {
    return run(tick + 1);
  }

  return 0;
}

console.log(run());

The program will crash because the maximum call stack size was exceeded.

If I do this in Go:

package main

import "fmt"

func run(tick int) (int) {
    if (tick < 1000000) {
        return run(tick + 1)
    }

    return 0
}

func main() {
    fmt.Println(run(0))
}

This will run and print 0 to stdout.

My questions are:

  • Is there a maximum number of calls above which the Go example I gave would fail?
  • Is code like this an anti-pattern in Go?
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1条回答 默认 最新

  • dony39517 2018-04-20 11:32
    已采纳

    In Go, goroutines do not have a fixed stack size. Instead they start small (with like 4KB), and grow / shrink when needed, seemingly giving the feeling of an "infinite" stack (of course it can't be truly infinite).

    Yes, there is a limit. But this limit does not come from a call depth limit, but rather the stack memory limit. This limit is enforced by the Go runtime, but it is usually hundreds of MBs (or even a GB). On the Go Playground it's 250MB, which can be seen on this Go Playground Example.

    On my local Linux 64-bit machine it's 1 GB.

    Recommended reading: Dave Cheney: Why is a Goroutine's stack infinite?

    Returning to your example: increasing the max recursion call to 1e9 will run out of the stack:

    if (tick < 1000000000) { ... }
    

    This will result in:

    runtime: goroutine stack exceeds 1000000000-byte limit
    fatal error: stack overflow
    
    runtime stack:
    runtime.throw(0x4b4730, 0xe)
            /usr/local/go/src/runtime/panic.go:619 +0x81
    runtime.newstack()
            /usr/local/go/src/runtime/stack.go:1054 +0x71f
    runtime.morestack()
            /usr/local/go/src/runtime/asm_amd64.s:480 +0x89
    
    goroutine 1 [running]:
    main.run(0xffffde, 0x0)
            /home/icza/gows/src/play/play.go:5 +0x62 fp=0xc440088370 sp=0xc440088368 pc=0x483262
    main.run(0xffffdd, 0x0)
            /home/icza/gows/src/play/play.go:7 +0x36 fp=0xc440088390 sp=0xc440088370 pc=0x483236
    main.run(0xffffdc, 0x0)
    ...
    
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