原文写于：2008-02-04
这几天在看C#多线程的东东，确保多个线程不死锁是比较难的，但要死锁很容易。试着写了段死锁的代码，见下文。
环境：.NET 2.0
基本思路：学OS时的经典问题，两个线程抢占两个资源，线程1抢到了资源A，还需要资源B；线程2抢到了资源B，还需要资源A；结果就死锁了。
1
using System;
2 using System.Collections.Generic;
3 using System.Text;
4 using System.Threading;
5
6 namespace MultiThreadTest
7
{
8
class Program
9
{
10 static void Main(string[] args)
11 {
12 Deadlock#region Deadlock
13 Deadlock DL = new Deadlock();
14 Thread DL1 = new Thread(DL.StartFromLocker1);
15 Thread DL2 = new Thread(DL.StartFromLocker2);
16
17 DL1.Start();
18 DL2.Start();
19
#endregion
20 }
21
23 }
24
25 class Deadlock
26 {
27 object locker1 = new object();
28 object locker2 = new object();
29 string s1="StartFromLocker1", s2="StartFromLocker2";
30 string l1 = "locker1", l2 = "locker2";
31
32 public void StartFromLocker1()
33 {
34 lock(locker1)
35 {
36 Console.WriteLine("{0} got {1}", s1, l1);
37 Thread.Sleep(500);
38 Console.WriteLine("{0} waiting for {1}", s1, l2);
39 lock(locker2)
40 {
41 Console.WriteLine("{0} got {1}", s1, l2);
42 Thread.Sleep(500);
43 }
44 }
45 Console.WriteLine("leaving {0}", s1);
46 }
47
48 public void StartFromLocker2()
49 {
50 lock (locker2)
51 {
52 Console.WriteLine("{0} got {1}", s2, l2);
53 Thread.Sleep(500);
54 Console.WriteLine("{0} waiting for {1}", s2, l1);
55 lock (locker1)
56 {
57 Console.WriteLine("{0} got {1}", s2, l1);
58 Thread.Sleep(500);
59 }
60 }
61 Console.WriteLine("leaving {0}", s2);
62 }
63 };
64
}
运行结果：
StartFromLocker1 got locker1
StartFromLocker2 got locker2
StartFromLocker1 waiting for locker2
StartFromLocker2 waiting for locker1