[fpc-pascal] How to find where my app consumes CPU?

[Bo Berglund]

On Tue, 18 May 2021 21:40:15 +0000, Alexander Grotewohl via fpc-pascal
<fpc-pascal at lists.freepascal.org> wrote:

>if it's waiting on keyboard input you might be better off using select() for 
>that instead of looping and checking for keyboard input each go around.
>
>sleep() might already do something similar with a zero timeout but even that 
>would probably be insufficient

As I tried to explain at the start of this thread my application runs as a
*systemd service* on Linux, so there is absolutely no keyboard input.

The main program looks like this after initializations etc:

  try
    try
      bSTerm := False;
      bSInt := False;
      bsHup := False;
      {$IFDEF UNIX}
      fpSignal(SigTerm, SignalHandler(@handleSignal));
      fpSignal(SigInt, SignalHandler(@handleSignal));
      fpSignal(SigHup, SignalHandler(@handleSignal));
      {$ENDIF}

      Debug_Writeln('Enter eternal loop');
      FLogServ.StdLog('Enter eternal loop');

      While not (bSTerm or bSInt or bsHup) do
      begin
        //Here is where the server runs as defined elsewhere
        //Eternal loop to wait for system messages
        Sleep(1); //To not hog the CPU
        CheckSynchronize; //To get thread comm working
      end;

      Debug_Writeln('Exit eternal loop');
      FLogServ.StdLog('Exit eternal loop');
    except
      on E: Exception do
      begin
        FLogServ.ExceptionLog('Unhandled exception: ' + E.Message);
      end;
    end;
  finally
    ShutdownServer;
  end;

As you can see it sits in the eternal loop until the system sends a "signal" to
it to stop. So systemd does that if I issue a sudo systemctl stop myservice and
this works fine.
Could this tiny loop consume 6-7% CPU cycles?


-- 
Bo Berglund
Developer in Sweden