关于多线程同步向Memo1中写数据的问题（高手请进）

Question

以下代码
unit Unit1;interfaceuses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, Buttons;type  TMainThread = class(TThread)
  private
    FCount: LongInt;
    procedure WriteFcout;
  public
    procedure Execute; override;
    constructor Create(IsSuspend: Boolean);
  end;
  TCenterThread = class(TThread)
  private
    FCount: LongInt;
    procedure WriteFcout;
  public
    procedure Execute; override;
    constructor Create(IsSuspend: Boolean);
  end;
  TForm1 = class(TForm)
    Button1: TButton;
    Memo1: TMemo;
    procedure Button1Click(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
    procedure FormShow(Sender: TObject);
  private
    { Private declarations }
    FP: TStringList;
  public
    { Public declarations }  end;var
  Form1: TForm1;
  ThreadLock: LongInt;
  MainThread: TMainThread;
  CenterThread: TCenterThread;
implementation{$R *.dfm}constructor TMainThread.Create(IsSuspend: Boolean);
begin
  inherited Create(IsSuspend);
  FreeOnTerminate := True;
  FCount := 0;
end;procedure TMainThread.Execute;
var i: Integer;
begin
  i := 0;
  while i < 10 do
  begin
    Inc(FCount);
    Synchronize(WriteFcout);    
    InterlockedIncrement(ThreadLock);
    if CenterThread.Suspended then
      CenterThread.Resume;
    Inc(i);
  end;
end;procedure TMainThread.WriteFcout;
begin
  Form1.Memo1.Lines.Add('A');
end;constructor TCenterThread.Create(IsSuspend: Boolean);
begin
  inherited Create(IsSuspend);
  FreeOnTerminate := True;
  FCount := 0;
end;procedure TCenterThread.Execute;
var i: LongInt;
begin
  while not Terminated do
  begin
    if ThreadLock > 0 then
    begin
      InterlockedDecrement(ThreadLock);
      Inc(FCount);
      Synchronize(WriteFcout);    
   end
    else
      Suspend;
  end;
end;procedure TCenterThread.WriteFcout;
begin
  Form1.Memo1.Lines.Add('B');
end;procedure TForm1.Button1Click(Sender: TObject);
var i: LongInt;
begin
  if MainThread.Suspended then
    MainThread.Resume;
end;
procedure TForm1.FormDestroy(Sender: TObject);
begin
  MainThread.Terminate;
  CenterThread.Terminate;
end;procedure TForm1.FormShow(Sender: TObject);
begin
  MainThread := TMainThread.Create(True);
  CenterThread := TCenterThread.Create(True);
  ThreadLock := 0;
end;end.
按 Button1后得 Memo1中得到结果如下。
A
B
A
A
A
A
A
A
A
A
A
请问是什么原因
理想结果应该是10个A，10个B 交替出现，但是在只有10个A、1个B 请问是什么原因

Answer 1

你把ThreadLock的值打印出来就知道是怎么回事了。

Answer 2

procedure TCenterThread.Execute;
var i: LongInt;
begin
while not Terminated do
begin
  if ThreadLock > 0 then
  begin
    Sleep(1);
    Inc(FCount);
    Synchronize(WriteFcout);
    InterlockedDecrement(ThreadLock);    if MainThread.Suspended then
      MainThread.Resume;
    Suspend;
  end
end;
end;
procedure TMainThread.Execute;
var i: Integer;
begin
  i := 0;
  while i < 10 do
  begin
    Sleep(1);
    Inc(FCount);
    Synchronize(WriteFcout);
    InterlockedIncrement(ThreadLock);    if CenterThread.Suspended then
      CenterThread.Resume;
    Inc(i);
    Suspend;
  end;
end;

Answer 3

并不是用了多线程就会提高程序的效率，如果不是多cpu，有时效率反而会降低

Answer 4

唤醒并不等于马上执行，只有请求到cpu时间才可能执行，感觉是两个线程同时请求，先处理哪个是不一定的，

Answer 5

补充
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