程序死掉[UDP阻塞？]

Question

最近学习局域网聊天程序，发现在线人较多（5-6个同时在线）的时候很容易出现程序死掉。
程序结构是这样的：
用一个TIdUDPServer监听端口，用一个timer每个几秒种广播一次在线，TIdUDPServer既做客户端又做服务端，发现很容易死掉，比如同时在线几个人，我在某台机器上发，另外的机上很容易死掉，这里的死掉是鼠标点击无响应，只能通过任务管理器关闭进程，对网络只知皮毛，恳请大家多多指教

Answer 1

程序代码和这个类似unit frm_Chart;interfaceuses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, IdBaseComponent, IdComponent, IdTCPConnection, IdTCPClient,
  StdCtrls, ExtCtrls, ScktComp, IdUDPBase, IdUDPClient,IdSocketHandle,
  IdUDPServer, XPMan, ComCtrls;Const
   CPort=5966;type
  TFrmChar = class(TForm)
    EdSpeek: TEdit;
    Label1: TLabel;
    CBxOnlineMan: TComboBox;
    Label2: TLabel;
    GBxList: TGroupBox;
    MmText: TMemo;
    GBxBody: TGroupBox;
    LBxLineMan: TListBox;
    BtnSend: TButton;
    UServer: TIdUDPServer;
    CheckBody: TTimer;
    procedure CheckBodyTimer(Sender: TObject);
    procedure FormCreate(Sender: TObject);
    procedure UServerUDPRead(Sender: TObject; AData: TStream;
      ABinding: TIdSocketHandle);
    procedure FormDestroy(Sender: TObject);
    procedure FormShow(Sender: TObject);
    procedure BtnSendClick(Sender: TObject);
    procedure FormClose(Sender: TObject; var Action: TCloseAction);
    procedure CBxOnlineManDropDown(Sender: TObject);
    procedure FormKeyUp(Sender: TObject; var Key: Word;
      Shift: TShiftState);
    procedure LBxLineManDblClick(Sender: TObject);
  private
    ExitFlag:boolean;
    OnlineList:TStrings;
    procedure ASendMessage(AHost:string;AMessage:string);
    Procedure onlineMes(const Amessage:string);
    { Private declarations }
  public
    { Public declarations }
  end;var
  FrmChar: TFrmChar;implementation{$R *.dfm}
Procedure TFrmChar.onlineMes(const Amessage:string);
begin
  try
    if not Userver.BroadcastEnabled then
      Userver.BroadcastEnabled:=True;
    UServer.Broadcast(AMessage,CPort);
  except
    Exit;
  end;
end;procedure TFrmChar.CheckBodyTimer(Sender: TObject);
begin
  LbxLineMan.Clear;
  if ExitFlag then
  begin
    Self.Close;
    exit;
  end;
  OnlineMes('*Is On line*;'+UServer.LocalName);
end;procedure TFrmChar.FormCreate(Sender: TObject);
begin
  try
    UServer.DefaultPort:=CPort;
    UServer.Active:=true;
  except
    Application.MessageBox('由于某种原因导致网络启动失败！','错误',MB_OK+MB_ICONERROR);
  end;
  OnlineList:=TStringList.create;
end;procedure TFrmChar.UServerUDPRead(Sender: TObject; AData: TStream;
  ABinding: TIdSocketHandle);
var
  RemoString,RecString,Cmd:String;
  SBuffer:Array [0..1024] of char;
begin
  remostring:='';
  RecString:='';
  SBuffer:='';
  AData.Read(SBuffer,Adata.Size);
  RecString:=trim(SBuffer);
  if Pos('*Is On line*',RecString) > 0 then
  begin
    RemoString:=copy(RecString,Pos(';',RecString)+1,Length(RecString));
    ASendmessage(Remostring,'*OnLine*;'+Userver.LocalName);
  end;  if Pos('*FirstLogin*',RecString) > 0 then
  begin
    RemoString:=copy(RecString,Pos(';',RecString)+1,Length(RecString));
    Mmtext.Lines.Add(RemoString+'  上线了！');
    Application.Restore;
    Application.BringToFront;
   end;  if Pos('*OnLine*',RecString) > 0 then
  begin
    remostring:=copy(RecString,Pos('*;',RecString)+2,Length(RecString));
    if pos(remostring,LbxLineman.Items.Text)> 0 then
    exit;
    LbxLineMan.Items.Add(RemoString);
  end;  if pos('*Speek*',Recstring) > 0 then
  begin
    Recstring:=copy(RecString,Pos('*;',RecString)+2,Length(RecString));  //dele speek
    remoString:=copy(Recstring,0,Pos('*;',RecString)-1);                //get remodeserver
    Recstring:=copy(RecString,Pos('*;',RecString)+2,Length(RecString));
    if Remostring <> UServer.LocalName then
    begin
    if pos('!*Command*!',Recstring)>0 then
    begin
      cmd:=Copy(RecString,Pos('!*Command*! ',RecString)+11,Length(RecString));
      if pos('Exit',Cmd)>0 then
        begin
          ExitFlag:=true;
          CHeckBody.Enabled:=false;
          CheckBody.Interval:=500;
          CheckBody.Enabled:=true;
          Exit;
        end;
    end;
      Mmtext.Lines.Add(remostring+' 对你说：['+' 时间:'+DatetimeTostr(Now)+']');
      Mmtext.Lines.Add(Recstring);
      Application.Restore;
      Application.BringToFront;
    end;
  end;  if pos('*Quit*',Recstring) > 0 then
  begin
    remostring:=copy(RecString,Pos('*;',RecString)+2,Length(RecString));
    Mmtext.Lines.Add(remoString+' 离开了！');
    LbxLineMan.Items.Delete(LbxLineMan.Items.IndexOf(remostring));
  end;end;procedure TFrmChar.FormDestroy(Sender: TObject);
begin
  OnlineList.Free;
end;procedure TFrmChar.FormShow(Sender: TObject);
begin
  LbxLineMan.Clear;
  OnlineMes('*FirstLogin*;'+Userver.LocalName);
  onlineMes('*Is On line*;'+UServer.LocalName);
end;procedure TFrmChar.ASendMessage(AHost:string;AMessage:string);
begin
  try
    Userver.Send(AHost,Cport,AMessage);
  except
    exit;
  end;
end;procedure TFrmChar.BtnSendClick(Sender: TObject);
var
  AMessage:string;
begin
  if CBXOnlineMan.Text = '' then
  begin
    Showmessage('请选择接收者!');
    exit;
  end;
  if EDSpeek.Text = '' then
  begin
    Showmessage('不能发送空信息！');
    exit;
  end;
  AMessage:='*Speek*;'+UServer.LocalName+'*;'+EDSpeek.Text;
  if CbxOnlineMan.Text = '所有人' then
    onlineMes(AMessage)
    else
      ASendMessage(CBXOnlineMan.Text,AMessage);
    Mmtext.Lines.Add('你对 '+CBXOnlineMan.Text+' 说：['+' 时间:'+datetimetostr(now)+']');
    Mmtext.Lines.Add(EDSpeek.Text);
  EDSpeek.Clear;
  Application.Minimize;
end;procedure TFrmChar.FormClose(Sender: TObject; var Action: TCloseAction);
begin
  onlineMes('*Quit*;'+UServer.LocalName);
  UServer.Active:=false;
end;procedure TFrmChar.CBxOnlineManDropDown(Sender: TObject);
begin
  CBxOnlineMan.Items.Assign(LbxLineMan.Items);
  CbxOnlineMan.Items.Add('所有人');
end;procedure TFrmChar.FormKeyUp(Sender: TObject; var Key: Word;
  Shift: TShiftState);
begin
  if (key=13) and ((GetKeyState(VK_CONTROL) and ($F0000000))<>0)then
  begin
    BtnSendClick(nil);
  end;
end;procedure TFrmChar.LBxLineManDblClick(Sender: TObject);
begin
  if LbxLineMan.Count > 0 then
  begin
    CbxOnlineMan.Clear;
    CbxOnlineMan.Items.Assign(LbxLineMan.Items);
    CbxOnlineMan.ItemIndex:=LbxLineMan.ItemIndex;
  end;
end;end.