多线程同步 CS : TCriticalSection; 定义放在哪里？

[疯狂低调]

在主窗口中含有两个公共变量 pbArray 、pb，两个线程同时写入改两个变量的内容。 未防止同步错误，加入了 CS : TCriticalSection ，但不清楚下面的定义及使用方法是否有错？
另外：如果没有错误的话，在每个线程内部定义的局部 CS : TCriticalSection在进行同步操作时如何确定另外线程的 CS : TCriticalSection对象能够正确被使用，而不是同时都使用？
线程1

procedure TH1.Execute;
var
 n : integer;
 CS : TCriticalSection;
begin
  { Place thread code here }
  CS := TCriticalSection.Create;
  form1.Label1.Caption := IntToStr(self.ThreadID);
  while not Self.Terminated do
   begin
    sleep(20);
    for n := 0 to high(Form1.pbArray) do
     begin

        form1.ProgressBar1.Position := n;

        CS.Acquire;
        try
            form1.pbArray[n] := FormatDateTime('yyyy-mm-dd hh:nn:ss:zzz',now);
            form1.pb         := FormatDateTime('yyyy-mm-dd hh:nn:ss:zzz',now);
        finally
            CS.Release;
        end;
     end;

    //CRITICAL_SECTION
   end;

end;

线程2

procedure TH2.Execute;
var
 n : integer;
 CS : TCriticalSection;
begin

  { Place thread code here }
  CS := TCriticalSection.Create;
  form1.Label2.Caption := IntToStr(self.ThreadID);
  while not Self.Terminated do
   begin
    sleep(20);
    for n := 0 to high(Form1.pbArray) do
     begin

        form1.ProgressBar2.Position := n;

        CS.Acquire;
        try
            form1.pbArray[n] := FormatDateTime('yyyy-mm-dd hh:nn:ss:zzz',now);
            form1.pb         := FormatDateTime('yyyy-mm-dd hh:nn:ss:zzz',now);
        finally
        CS.Release;
        end;
     end;



   end;

end;

[mygodsos]

一、临界区
所谓临界区，就是一次只能由一个线程来执行的一段代码。如果把初始化数组的代码放在临界区内，另一个线程在第一个线程处理完之前是不会被执行的。
使用临界区的步骤：
1、先声明一个全局变量类型为TRTLCriticalSection；
2、在线程Create()前调用InitializeCriticalSection()过程来初始化，该函数定义是：
void WINAPI InitializeCriticalSection(LPCRITICAL_SECTION lpCriticalSection);
类型lpCriticalSection即是Delphi封装的TRTLCriticalSection。
3、在线程的需要放入临界区的代码前面使用EnterCriticalSection(lpCriticalSection)过程来开始建立临界区。在代码完成后用LeaveCriticalSection(lpCriticalSection)来标志临界区的结束。
4、在线程执行完后用DeleteCriticalSection(lpCriticalSection)来清除临界区。这个清除过程必须放在线程执行完后的地方，比如FormDesroy事件中。上面的例子中，若把该过程放在TMyThread.Create(False);后，会产生错误。

=================
主要目的是把读写全局数据的语句放在临界区去，这样在一个线程读写完成全，另一个线程会等待

[疯狂低调]

多谢楼上几位的帮忙，已对临界区有了些许的概念，似乎我只需要在写公共变量时加入临界区机制即可，读取操作应该不用临界区参与吧？

[mygodsos]

要区分读写的比较复杂，用用TMultiReadExclusiveWriteSynchronizer类来阻塞，可以写成TMREWSync

这样随便你，你想阻塞读或者写都成。

[lake_cx]

放在哪我管不着，我只能告诉你
一个TCriticalSection表示一个临界区，你就看成一张门，门里面只能有一个线程进去，如果里面有线程，其他线程就进不去，知道其他线程出来。
你如果创建了两个TCriticalSection，那就表示有两张门，如果线程要同步访问一个对象或内存，你应该只给它们搞一张门。

[疯狂低调]

随后我又写了如下的解决办法，请问高手哪种比较可取，需要注意些什么？

主窗体代码:

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, ComCtrls, unit2,unit3,SyncObjs;

type
  TForm1 = class(TForm)
    ProgressBar1: TProgressBar;
    ProgressBar2: TProgressBar;
    Button1: TButton;
    Label1: TLabel;
    Label2: TLabel;
    procedure Button1Click(Sender: TObject);
    procedure FormClose(Sender: TObject; var Action: TCloseAction);
    procedure FormCreate(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
  private
    { Private declarations }

    t1 : TH1;
    t2 : TH2;
  public
    { Public declarations }
    pbArray : array[0..2000] of string;
    pb : string;
    //CS : TCriticalSection;

  end;

var
  Form1: TForm1;
     Lock : TRTLCriticalSection;
implementation

{$R *.dfm}

 
procedure TForm1.Button1Click(Sender: TObject);
begin

 t1 := TH1.Create(false);

 t2 := TH2.Create(false);

end;

procedure TForm1.FormClose(Sender: TObject; var Action: TCloseAction);
begin
 t1.Terminate;
 t2.Terminate;

 FreeAndNil(t1);
 FreeAndNil(t2);
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
InitializeCriticalSection(Lock);
end;

procedure TForm1.FormDestroy(Sender: TObject);
begin
DeleteCriticalSection(Lock);

end;

end.

线程1代码：

unit Unit2;

interface

uses
  Classes,SysUtils,SyncObjs,Windows;

type
  TH1 = class(TThread)
  private
    { Private declarations }
  protected
    procedure Execute; override;
  end;

implementation

{ Important: Methods and properties of objects in visual components can only be
  used in a method called using Synchronize, for example,

      Synchronize(UpdateCaption);

  and UpdateCaption could look like,

    procedure TH1.UpdateCaption;
    begin
      Form1.Caption := 'Updated in a thread';
    end; }

{ TH1 }
 uses
  unit1;
procedure TH1.Execute;
var
 n : integer;
 //CS : TCriticalSection;
begin
  { Place thread code here }
  //CS := TCriticalSection.Create;
  form1.Label1.Caption := IntToStr(self.ThreadID);
  while not Self.Terminated do
   begin
    sleep(20);
    for n := 0 to high(Form1.pbArray) do
     begin

        form1.ProgressBar1.Position := n;

        //CS.Acquire;
        EnterCriticalSection(lock);

        try
            form1.pbArray[n] := FormatDateTime('yyyy-mm-dd hh:nn:ss:zzz',now);
            form1.pb         := FormatDateTime('yyyy-mm-dd hh:nn:ss:zzz',now);
        finally
            //CS.Release;
        LeaveCriticalSection(lock);
        end;
     end;

    //CRITICAL_SECTION
   end;

end;

end.

{

var criticalsection: TCriticalsection;
创建：criticalsection := TCriticalsection.create;
使用：
criticalsection.enter;
try
...
finally
criticalsection.leave;
end;
}

线程2代码

unit Unit3;

interface

uses
  Classes,SysUtils,SyncObjs,Windows;

type
  TH2 = class(TThread)
  private
    { Private declarations }
  protected
    procedure Execute; override;
  end;

implementation

{ Important: Methods and properties of objects in visual components can only be
  used in a method called using Synchronize, for example,

      Synchronize(UpdateCaption);

  and UpdateCaption could look like,

    procedure TH2.UpdateCaption;
    begin
      Form1.Caption := 'Updated in a thread';
    end; }

{ TH2 }
uses
 unit1;
procedure TH2.Execute;
var
 n : integer;
 //CS : TCriticalSection;
begin

  { Place thread code here }
  //CS := TCriticalSection.Create;
  form1.Label2.Caption := IntToStr(self.ThreadID);
  while not Self.Terminated do
   begin
    sleep(20);
    for n := 0 to high(Form1.pbArray) do
     begin

        form1.ProgressBar2.Position := n;
        EnterCriticalSection(lock);

        try
            form1.pbArray[n] := FormatDateTime('yyyy-mm-dd hh:nn:ss:zzz',now);
            form1.pb         := FormatDateTime('yyyy-mm-dd hh:nn:ss:zzz',now);
        finally
            //CS.Release;
        LeaveCriticalSection(lock);
        end;


        {
        CS.Acquire;
        try
            form1.pbArray[n] := FormatDateTime('yyyy-mm-dd hh:nn:ss:zzz',now);
            form1.pb         := FormatDateTime('yyyy-mm-dd hh:nn:ss:zzz',now);
        finally
        CS.Release;
        end;
        }
     end;



   end;

end;

end.

[CaiBirdy]

内核对象比全局变量还全局，，你认为它是放哪里的。。？