type
  TPingThread = class(TThread)
  private
    FClient: TClient;
    FOnPingDone: TNotifyEvent;
  protected
    procedure Execute; override;
  public
    constructor Create(const AHost: string);
    destructor Destroy; override;
    property OnPingDone: TNotifyEvent read FOnPingDone write FOnPingDone;
    property ReturnValue;
  end;
  
implementation
  
constructor TPingThread.Create(const AHost: string);
begin
  FOnPingDone:= nil;
  FreeOnTerminate:= True;
  FClient:= TClient.Create(AHost);
  FClient.Port:= 80;
  inherited Create(False);
end;

destructor TPingThread.Destroy;
begin
  FClient.Free;
  inherited;
end;

procedure TPingThread.Execute;
begin
  if Assigned(FClient) then
      ReturnValue:= Integer(FClient.IsAlive);
  if Assigned(FOnPingDone) then
      FOnPingDone(Self);
end;

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Unexpected Memory Leak
---------------------------
An unexpected memory leak has occurred. The unexpected small block leaks are:

1 - 12 bytes: TObject x 1
21 - 28 bytes: AnsiString x 1
61 - 68 bytes: Unknown x 1
69 - 76 bytes: TPingThread x 1
93 - 100 bytes: TClient x 1

---------------------------
OK  
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