多线程中全局变量的冲突?

Question

使用idtcpserver,设置了全局变量online,一个个下线时正常，但是同时下线时出错，只能下线一个，代码如下:procedure Tmain.IdTCPServer1Execute(AThread: TIdPeerThread);
 var
 i:integer;
 msg:RmessageData;
 rec:RrectiveData;
begin
  
 athread.Connection.ReadBuffer(msg,sizeof(msg));
if msg.command='offOnline' then
  begin
   EnterCriticalSection(cs);
   try
     tmpmsg:=msg;//全局变量，将msg传给Synchronize(offonline);
     for i:=0 to high(online) do  //删除下线用户的联机节点
       begin
         if msg.userName=online[i].userName then
           begin
             online[i]:=online[high(online)];
             setlength(online,high(online));
             break;
           end;
       end;
    
     for i:=0 to high(online) do   //发送下线用户的用户名
       begin
         rec.command:='deleOnline';
         rec.userName:=msg.userName;
         online[i].AThread.Connection.WriteBuffer(rec,sizeof(rec));
       end;
     finally
       LeaveCriticalSection(cs);
     end;
     athread.Synchronize(offonline);   end;

Answer 1

经过测试,问题出在这段代码上:
for i:=0 to high(online) do   //发送下线用户的用户名
       begin
         rec.command:='deleOnline';
         rec.userName:=msg.userName;
         online[i].AThread.Connection.WriteBuffer(rec,sizeof(rec));
       end;
大家帮我看下出错的原因是什么,要怎样改才可以?

Answer 2

问题已解决,改后代码如下:
 if msg.command = 'offOnline' then   //客户端下线事件
  begin
    cs.Acquire;
    try
      for i := 0 to high(online) do  //删除下线用户的联机节点
      begin
        if msg.userName = online[i].userName then
        begin
          online[i] := online[high(online)];
          setlength(online,high(online));
          break;
        end;
      end;
    finally
      cs.Release;
    end;
    cs.Acquire;
    try
      for i := 0 to listview1.Items.Count-1 do
      begin
        if listview1.Items.Item[i].Caption = msg.userName then
        begin
          listview1.Items.Item[i].Delete;
          break;
        end;
      end;
      memo1.Lines.Add('用户 '+msg.userName+' 下线了');
    finally
      cs.Release;
    end;
    for i := 0 to high(online) do   //发送下线用户的用户名
    begin
      rec.command := 'deleOnline';
      rec.userName := msg.userName;
      online[i].AThread.Connection.WriteBuffer(rec,sizeof(rec));     end;
  end;