Delphi 7 + Indy + Multithread clients

Question

My PC is connected to two electronic devices that send data using a TCP connection. I would like to develop a Delphi program able to log all this data. In the following code I create two TCPClients using two threads. I am able to log data from one device using one thread, but when two threads are runnning the application freezes. I don´t have experience programming in Delphi, sorry if there are too many mistakes... I am using Delphi 7. What can I do to avoid freezing the app?

Thanks in advance

//************************************************************************//
type TThreadConn1 = class(TThread)
    private
    protected
        procedure Execute; override;
    end;

type TThreadConn2 = class(TThread)
    private
    protected
        procedure Execute; override;
    end;


var
    Form1: TForm1;
    TCP1: TThreadConn1;
    TCP2: TThreadConn2;
    flag1: bool;
    flag2: bool;


implementation
{$R *.dfm}

//******************************Connection 1******************************//
procedure TThreadConn1.Execute;  //Connect+loop read buffer+disconnect
begin
    Form1.IdTCPClient1.Connect;  
    While flag1 = false do   
        Form1.IdTCPClient1.CurrentReadBuffer;
    Form1.IdTCPClient1.Disconnect;
end; 

procedure TForm1.ButtonConnection1Click(Sender: TObject);
begin
    flag1:=false;
    TCP1 := TThreadConn1.Create(false);  //Launch thread 
end;

procedure TForm1.ButtonDisconnection1Click(Sender: TObject);
begin
    flag1:=true;
    if (TCP1.Terminated = false) then
        TCP1.Terminate;   //Is it ok to finish this way a thread?
    end;

//******************************Connection2******************************//
procedure TThreadConn2.Execute;  //Connect+loop read buffer+disconnect
begin
    Form1.IdTCPClient2.Connect;
    While flag2 = false do   
        Form1.IdTCPClient1.CurrentReadBuffer;
    Form1.IdTCPClient2.Disconnect;
end; { of procedure }

procedure TForm1.ButtonConnection2Click(Sender: TObject);
begin
    flag2:=false;
    TCP2 := TThreadConn2.Create(false);
end;

procedure TForm1.ButtonDisconnection2Click(Sender: TObject);
begin
    flag2:=true;
    if (TCP2.Terminated = false) then
        TCP2.Terminate;
end;
end.

Answer 1

You don't need to create two separate threads that do the same thing. Create one class and then instantiate multiple copies of it. Try this instead:

type
  TThreadConn = class(TThread)
  private
    FClient: TIdTCPClient;
  protected
    procedure Execute; override;
  public
    constructor Create(AClient: TIdTCPClient);
  end;

var
  TCP1: TThreadConn = nil;
  TCP2: TThreadConn = nil;

constructor TThreadConn.Create(AClient: TIdTCPClient);
begin
  inherited Create(False);
  FClient := AClient;
end;

procedure TThreadConn.Execute;
begin
  FClient.Connect;  
  try
    while Terminated = false do   
      FClient.CurrentReadBuffer;
  finally
    FClient.Disconnect;
  end;
end; 

procedure TForm1.ButtonConnection1Click(Sender: TObject);
begin
  TCP1 := TThreadConn.Create(TIdTCPClient1);
end;

procedure TForm1.ButtonDisconnection1Click(Sender: TObject);

begin if (TCP1 <> nil) then begin TCP1.Terminate; TCP1.WaitFor; FreeAndNil(TCP1); end; end;

procedure TForm1.ButtonConnection2Click(Sender: TObject);

begin TCP2 := TThreadConn.Create(IdTCPClient2); end;

procedure TForm1.ButtonDisconnection2Click(Sender: TObject);
begin
  if (TCP2 <> nil) then
  begin
    TCP2.Terminate;
    TCP2.WaitFor;
    FreeAndNil(TCP2);
  end;
end;