如何从Golang程序中设置ulimit -n？

  • Z时代
  • 2024-01-10
  • 分类：问答

我的目的是从golang程序中设置ulimit -n，这样我就不必全局设置它，而将其限制在程序中。

找到相同的系统调用setrlimit和get

rlimit。（http://linux.die.net/man/2/setrlimit）

但是，当我尝试使用相同的示例程序时，在设置值时出现错误，提示参数无效。

    package main
    import (
         "fmt"
         "syscall"
     )
    func main() {
        var rLimit syscall.Rlimit
        err := syscall.Getrlimit(syscall.RLIMIT_NOFILE, &rLimit)
        if err != nil {
                fmt.Println("Error Getting Rlimit ", err)
        }
        fmt.Println(rLimit)
        rLimit.Max = 999999
        rLimit.Cur = 999999
        err = syscall.Setrlimit(syscall.RLIMIT_NOFILE, &rLimit)
        if err != nil {
            fmt.Println("Error Setting Rlimit ", err)
         }
         err = syscall.Getrlimit(syscall.RLIMIT_NOFILE, &rLimit)
         if err != nil {
            fmt.Println("Error Getting Rlimit ", err)
         }
         fmt.Println("Rlimit Final", rLimit)
         }

获得的输出为：

george@george-Not-Specified ~/work/odesk/progium/trial $ ./getRlimit 
{4294963002032703 0}
Error Setting Rlimit  invalid argument
Rlimit Final {4294963002032703 999999}
george@george-Not-Specified ~/work/odesk/progium/trial $ sudo ./getRlimit 
[sudo] password for george: 
{4294963002032703 0}
Error Setting Rlimit  invalid argument 
Rlimit Final {4294963002032703 999999}
george@george-Not-Specified ~/work/odesk/progium/trial $ uname -a
Linux george-Not-Specified 3.5.0-17-generic #28-Ubuntu SMP Tue Oct 9 19:32:08 UTC 2012 i686 i686 i686 GNU/Linux
george@george-Not-Specified ~/work/odesk/progium/trial $

因此，我能够获得rlimit设置限制失败并返回错误。即使失败，当我再次使用该值时，MAX值也已更改，但CUR值保持不变。该错误可能是由于我的内核出现问题还是程序错误？在哪里可以找到更多信息以及如何处理此类问题？

修复程序完成后可以工作。

george@george-Not-Specified ~/work/odesk/progium/trial $ go build getRlimit.go 
george@george-Not-Specified ~/work/odesk/progium/trial $ ./getRlimit 
{1024 4096}
Error Setting Rlimit  operation not permitted
Rlimit Final {1024 4096}
george@george-Not-Specified ~/work/odesk/progium/trial $ sudo ./getRlimit                                                                                               
[sudo] password for george: 
{1024 4096}
Rlimit Final {999999 999999}
george@george-Not-Specified ~/work/odesk/progium/trial $ uname -a
Linux george-Not-Specified 3.5.0-17-generic #28-Ubuntu SMP Tue Oct 9 19:32:08 UTC 2012    i686 i686 i686 GNU/Linux
george@george-Not-Specified ~/work/odesk/progium/trial $ go version
go version devel +7c42cfa28e24 Tue Jul 30 14:22:14 2013 +1000 linux/386

回答：

它按预期工作。

setrlimit（2）。

软限制是内核为相应资源强制执行的值。硬限制充当软限制的上限：无特权的进程只能将其软限制设置为0到硬限制之间的值，并且（不可逆地）降低其硬限制。特权进程（在Linux下：具有CAP_SYS_RESOURCE功能的进程）可以对两个限制值进行任意更改。

rlimit.go：

package main
import (
    "fmt"
    "syscall"
)
func main() {
    var rLimit syscall.Rlimit
    err := syscall.Getrlimit(syscall.RLIMIT_NOFILE, &rLimit)
    if err != nil {
        fmt.Println("Error Getting Rlimit ", err)
    }
    fmt.Println(rLimit)
    rLimit.Max = 999999
    rLimit.Cur = 999999
    err = syscall.Setrlimit(syscall.RLIMIT_NOFILE, &rLimit)
    if err != nil {
        fmt.Println("Error Setting Rlimit ", err)
    }
    err = syscall.Getrlimit(syscall.RLIMIT_NOFILE, &rLimit)
    if err != nil {
        fmt.Println("Error Getting Rlimit ", err)
    }
    fmt.Println("Rlimit Final", rLimit)
}

输出：

$ uname -a
Linux peterSO 3.8.0-26-generic #38-Ubuntu SMP Mon Jun 17 21:43:33 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux
$ go build rlimit.go
$ ./rlimit
{1024 4096}
Error Setting Rlimit  operation not permitted
Rlimit Final {1024 4096}
$ sudo ./rlimit
[sudo] password for peterSO:
{1024 4096}
Rlimit Final {999999 999999}

我成功参加rlimit.go了linux/amd64，你失败了linux/386。在Linux

32位发行版中Getrlimit以及SetrlimitLinux 32位发行版中都有一个执行错误。这些错误已得到修复。

使用Go default分支tip（包括错误修复），运行以下命令，并使用结果更新您的问题。

$ uname -a
Linux peterSO 3.8.0-26-generic #38-Ubuntu SMP Mon Jun 17 21:46:08 UTC 2013 i686 i686 i686 GNU/Linux
$ go version
go version devel +ba52f6399462 Thu Jul 25 09:56:06 2013 -0400 linux/386
$ ulimit -Sn
1024
$ ulimit -Hn
4096
$ go build rlimit.go
$ ./rlimit
{1024 4096}
Error Setting Rlimit  operation not permitted
Rlimit Final {1024 4096}
$ sudo ./rlimit
[sudo] password for peterSO: 
{1024 4096}
Rlimit Final {999999 999999}
$

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