一个内存泄露的例子

一个内存泄露的例子

主窗口：

 

namespace WindowsFormsApplication17

{

public partial class Form1 : Form

{

public Form1()

{

InitializeComponent();

}

 

public event EventHandler Form1Test;

 

private void button1_Click(object sender, EventArgs e)

{

var sb = new StringBuilder();

sb.AppendLine(GetTotalMemory());

for (int i = 0; i < 5; i++)

{

var form2 = new Form2() { Parent = this };

form2.Form2Test += new EventHandler(form2_Form2Test); // register event in Form2 doesn't cause memory leak.

form2.Show();

form2.Close();

GC.Collect();

sb.AppendLine(GetTotalMemory());

}

 

MessageBox.Show(sb.ToString());

}

 

void form2_Form2Test(object sender, EventArgs e)

{

}

 

public static string GetTotalMemory()

{

// bytes in current process' managed heap.

return GC.GetTotalMemory(true) / 1024 + " K";

}

}

}

 

子窗口：

namespace WindowsFormsApplication17

{

public partial class Form2 : Form

{

public Form2()

{

InitializeComponent();

}

 

private byte[] strs = new byte[50 * 1024 * 1024]; // 50MB

//You can very well make a static

//member eligible for a collection by setting it to null. Otherwise, a static

//member would last for the life of the appdomain in which it lies.

private static byte[] strss = new byte[20 * 1024 * 1024]; // 20MB

 

public event EventHandler Form2Test;

public Form1 Parent { get; set; }

 

protected override void OnLoad(EventArgs e)

{

Parent.Form1Test += new EventHandler(Form2_Form1Test);

base.OnLoad(e);

}

 

void Form2_Form1Test(object sender, EventArgs e)

{

}

 

protected override void OnClosing(CancelEventArgs e)

{

base.OnClosing(e);

// if don't unregister this event from parent, causes memory leak.

Parent.Form1Test -= new EventHandler(Form2_Form1Test);

}

}

}

 

静态字段strss在调用了GC.Collect();后还是存在的，它不会被回收。

在子form中注册父form的事件，如果不取消注册会导致内存泄露。

相反，在父form中注册子form的事件，不会导致内存泄露。

如果注释掉Parent.Form1Test -= new EventHandler(Form2_Form1Test);

运行结果如下，内存泄露了：

 

如果执行这句代码，运行结果如下，内存不泄露：

 

posted on 2012-04-23 17:00 cutebear 阅读( ...) 评论( ...) 编辑 收藏

转载于:https://www.cnblogs.com/bear831204/archive/2012/04/23/2466686.html