Delphi多线程编程之三同步读写全局数据

开始研究最重要的多线程读写全局数据了，结合书上的例子，我修改成下面的情况：

1. unit Tst_Thread3U;
3. interface
5. uses
7.   Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,Dialogs, StdCtrls;
9. type
10.   TForm1 = class(TForm)
11.     Button1: TButton;
12.     Memo1: TMemo;
13.     Button2: TButton;
14.     Button3: TButton;
15. procedure Button1Click(Sender: TObject);
16. procedure Button2Click(Sender: TObject);
17. procedure Button3Click(Sender: TObject);
18. private
19. procedure ThreadsDone(Sender: TObject);
20. end;
22.   TMyThread=class(TThread)
23. protected
24. procedure Execute;override;
25. end;
27. var
28.   Form1: TForm1;
30. implementation
31. {$R *.dfm}
33. const
34.   MaxSize=128;
35. var
36.   NextNumber:Integer=0;
37.   DoneFlags:Integer=0;
38.   GlobalArry:array[1..MaxSize] of Integer;
39.   Lock:byte;   //1-不同步  2-临界区 3-互斥
40.   CS:TRTLCriticalSection; //临界区
41.   hMutex:THandle;  //互斥
43. function GetNextNumber:Integer;
44. begin
45.   Result:=NextNumber;
46.   inc(NextNumber);
47. end;
49. procedure TMyThread.Execute;
50. var
51.   i:Integer;
52. begin
53.   FreeOnTerminate:=True; //终止后自动free
54.   OnTerminate:=Form1.ThreadsDone;
55. if Lock<>3 then //非互斥情况
56. begin
57. if Lock=2 then EnterCriticalSection(CS); //建立临界区
58. for i := 1 to MaxSize do
59. begin
60.       GlobalArry[i]:=GetNextNumber;
61.       Sleep(5);
62. end;
63. if Lock=2 then LeaveCriticalSection(CS);//离开临界区
64. end else //-------互斥
65. begin
66. if WaitForSingleObject(hMutex,INFINITE)=WAIT_OBJECT_0 then
67. begin
68. for i := 1 to MaxSize do
69. begin
70.         GlobalArry[i]:=GetNextNumber;
71.         Sleep(5);
72. end;
73. end;
74.     ReleaseMutex(hMutex);   //释放
75. end;
76. end;
78. procedure TForm1.ThreadsDone(Sender: TObject);
79. var
80.   i:Integer;
81. begin
82.   Inc(DoneFlags);
83. if DoneFlags=2 then
84. begin
85. for i := 1 to MaxSize do
86.       Memo1.Lines.Add(inttostr(GlobalArry[i]));
87. if Lock=2 then DeleteCriticalSection(CS); //删除临界区
88.        If Lock=3 then CloseHandle(hMutex); //关闭互斥
89. end;
90. end;
92. //非同步
93. procedure TForm1.Button1Click(Sender: TObject);
94. begin
95.   Lock:=1;
96.   TMyThread.Create(False);
97.   TMyThread.Create(False);
98. end;
100. //临界区
101. procedure TForm1.Button2Click(Sender: TObject);
102. begin
103.   Lock:=2; 
104.   InitializeCriticalSection(CS); //初始化临界区
105.   TMyThread.Create(False);
106.   TMyThread.Create(False);
107. end;
109. //互斥
110. procedure TForm1.Button3Click(Sender: TObject);
111. begin
112.   Lock:=3; // 互斥
113.   hMutex:=CreateMutex(0,False,nil);
114.   TMyThread.Create(False);
115.   TMyThread.Create(False);
116. end;
118. end.

没有临界区和互斥的帮助，两个线程都不断地在Memo1输出，而且数字是乱的。