doupian9798
2019-03-24 07:22 阅读 67
已采纳

屏幕锁定/关闭时,cmd.Run()会永久悬挂在Macos的golang中

I am running a golang app on Macos. It has some codes like the following:

for {
    time.Sleep(time.Second * 5)
    cmd := exec.Command("/usr/bin/osascript", "-e", `display dialog "hello" with title "hello"`)
    err := cmd.Run()
}

It works fine if I don't lock the screen (when the screen is always on). But the code err := cmd.Run() will hang forever if the screen is locked and off when that line executes. When I unlock the screen (turn it on), the for loop just hangs there forever and will never continue its execution.

I am not sure if this issue belongs to golang or how MacOS handles osascript. Can anyone please tell me how to workaround it? Thanks a lot.

PS: I use the same code in Linux and replace /usr/bin/osascript to /usr/bin/xmessage and this always works fine without any problems even if the screen is locked/off in Linux.

Edited:

My solution, use chrome instead:

cmd := exec.Command(`/Applications/Google Chrome.app/Contents/MacOS/Google Chrome`, "-new-window", "/path/hello.html")
  • 点赞
  • 写回答
  • 关注问题
  • 收藏
  • 复制链接分享

1条回答 默认 最新

  • 已采纳
    dou12754 dou12754 2019-03-24 07:48

    It seems to be related to how MacOS puts processes in idle when the screen locks. It makes the osasscriptchild process never finish execution and block the for loop.

    One thing you can do is run the command with a timeout context. I have tried and it works. Execution will resume when the screen is unlocked and timeout expires.

    Example:

    package main
    
    import (
        "context"
        "fmt"
        "os/exec"
        "time"
    )
    
    func main() {
        for {
            time.Sleep(time.Second * 5)
    
            // run your command with a timeout
            ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
            cmd := exec.CommandContext(
                ctx,
                "/usr/bin/osascript",
                "-e",
                `display dialog "hello" with title "hello"`,
            )
    
            err := cmd.Run()
            if err != nil {
                fmt.Println(err)
            }
            // don't forget to cancel your context to avoid context leak
            cancel()
        }
    }
    

    Alternatively, if you don't want a timeout you can check if the screen is locked before trying to call display dialog.

    package main
    
    import (
        "context"
        "fmt"
        "os"
        "os/exec"
        "strings"
        "time"
    )
    
    func main() {
        for {
            time.Sleep(time.Second * 5)
    
            ctx, cancel := context.WithTimeout(context.Background(), 1*time.Second)
            cmd := exec.CommandContext(
                ctx,
                "python",
                "-c",
                "import sys,Quartz; d=Quartz.CGSessionCopyCurrentDictionary(); print d",
            )
    
            var err error
            var b []byte
            if b, err = cmd.CombinedOutput(); err != nil {
                cancel()
                continue
            }
            cancel()
    
            // if screen is not locked
            if !strings.Contains(string(b), "CGSSessionScreenIsLocked = 1") {
                cmd = exec.Command(
                    "/usr/bin/osascript",
                    "-e",
                    "display dialog \"Hello\"",
                )
                cmd.Stdout = os.Stdout
                cmd.Stderr = os.Stderr
    
                err = cmd.Run()
                if err != nil {
                    fmt.Println("err: ", err)
                }
            }
        }
    }
    
    点赞 评论 复制链接分享

相关推荐