parallelize local simulation run

[ManuelaRunge]

The code below runs a batch file that loop through simulation in batches of 5 (separate batch files) but breaks if single simulation returns error, also the combine trajectories should only start after all trajectories were generated.
Running the code outside runScenarios works well (except those that break) and is faster as sequential run.

            file = open(os.path.join(trajectories_dir, 'runSimulations_loop.bat'), 'w')
            file.write('ECHO Run simulation number %x% to  %y%' + '\n' +
                       '\nFOR /L %%j IN (%x%,1,%y%) DO ( "{}" -c "{}" -m "{}") >> "{}/log/log_%x%_to_%y%.txt"'.format(
                get_cms_cmd(exe_dir, temp_exp_dir),
                os.path.join(temp_dir, "model_%%j" + ".cfg"),
                os.path.join(temp_dir, "simulation_%%j" + ".emodl"),
                os.path.join(trajectories_dir)
            ) + "\n ECHO end")

            file = open(os.path.join(trajectories_dir, 'runSimulations_parallel.bat'), 'w')
            file.write('@echo off' \
                        '\ncd {dir}\nfor /l %%i in (1,5,{nscen}]) do call :loop %%i' \
                        '\ngoto :eof' \
                        '\n\n:loop \ncall :checkinstances \nif %INSTANCES% LSS 5 (' \
                        '\n    echo Starting processing instance for %1' \
                        '\n    @set x=%1' \
                        '\n    @set step=%1+5' \
                        '\n    @set /a y=%x%+%step%' \
                        '\n    copy runSimulations_loop.bat runSimulations_loop%1.bat' \
                        '\n    start /min runSimulations_loop%1.bat 2 sec' \
                        '\n    goto :eof' \
                        '\n) \necho Waiting for instances to close ...\nping -n 2 ::1 >nul 2>&1\ngoto loop\ngoto :eof' \
                        '\n:checkinstances\nfor /f "usebackq" %%t in (`tasklist /fo csv /fi "imagename eq wait.bat"^|find /c /v ""`) do set INSTANCES=%%t' \
                        '\ngoto :eof' \
                        '\npause'.format(nscen=str(scen_num), dir=trajectories_dir))

(code modified from template on stackoverflow - example code)