定时器，事件和垃圾收集：我失去了一些东西？ [英] Timer, event and garbage collection : am I missing something?

问题描述

考虑以下code：

class TestTimerGC : Form
{
    public TestTimerGC()
    {
        Button btnGC = new Button();
        btnGC.Text = "GC";
        btnGC.Click += (sender, e) => GC.Collect();
        this.Controls.Add(btnGC);

        System.Windows.Forms.Timer tmr = new System.Windows.Forms.Timer();
        tmr.Interval = 1000;
        tmr.Tick += (sender, e) => this.Text = DateTime.Now.ToString();
        tmr.Start();
    }
}

如果我没有记错，在 TMR 变量超出范围，定时器不任何地方引用，所以它应该是符合垃圾收集。但是，当我点击GC按钮，定时器将继续运行，所以我想这是没有收集...

If I'm not mistaken, after the tmr variable goes out of scope, the Timer isn't referenced anywhere, so it should be eligible for garbage collection. But when I click the GC button, the timer continues to run, so I guess it wasn't collected...

有没有人有一个解释是什么？

Does anyone have an explanation for that ?

PS：这当然不是一个真正的程序，我只是想证明这一点的人......但我证明没有工作;）的

推荐答案

好了，我想我知道这是怎么回事......我看了看计时器的code 类反射器，我发现下面的指令在已启用 setter方法​​：

OK, I think I know what's going on... I looked at the code of the Timer class with Reflector, and I found the following instruction in the setter of the Enabled property :

this.timerRoot = GCHandle.Alloc(this);

因此​​，在启动时，定时器分配的GCHandle 的本身，$ P $由GC pvents其收藏...

So, when it is started, the timer allocates a GCHandle for itself, which prevents its collection by the GC...

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