Timer failing to trigger in very specific circumstances-CodePudding

I'm trying to use a System.Threading.Timer to exit a program after a certain number of seconds, and it's failing in specific circumstances. I've boiled it down to a minimum test case.

using System;
using System.Collections.Generic;
using System.Threading;

class test {
    static void SetTimer() {
        new Timer(a => Environment.Exit(0), null, 1000L, 0L);
    }

    static void Main(string[] args) {
        SetTimer();
        for (;;) {
            var v = new List<int>();
        }
    }
}

The above program should exit after one second, but it just hangs indefinitely.

But every part of the above code is necessary. The timer has to be set in a separate function; if it is set directly in Main, the program exits after one second. The infinite loop has to be doing something nontrivial; if it just increments an integer variable, the program exits after one second.

It's not the C# compiler per se at fault; the equivalent code in F# behaves the same way.

This is with Visual Studio 2022 on Windows 10, and csc -version is 4.1.0-5.22109.6 (0c82c411).

Is this a .Net bug, or am I doing something wrong?

CodePudding user response：

The problem is that your new Timer is already gone before the callback is executed. You should add a static Timer timer in the class that retains the object so it can keep executing. Here's my answer:

using System;
using System.Collections.Generic;
using System.Threading;

class test
{
    static Timer timer;
    static void SetTimer()
    {
        timer = new Timer(a =>
        {
            Environment.Exit(0);

        }, null, 1000L, 1000L);
    }

    static void Main(string[] args)
    {
        SetTimer();

        for (; ; )
        {
            var v = new List<int>();
        }
    }
}