<!-- GENERATED by tools/generators/examplesDocsEmitter.py from python/ - do not edit -->
(testmodels-fileheaderthreadstest)=
# fileHeaderThreadsTest.py

You can view and download this file on Github: [fileHeaderThreadsTest.py](https://github.com/jgerstmayr/EXUDYN/tree/master/python/TestModels/fileHeaderThreadsTest.py)

```{code-block} python
:linenos:

#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
# This is an EXUDYN example
#
# Details:  The version line of the solution and sensor file headers names the number of threads of the
#           computation (#1450): "#Exudyn version = ...; FLOAT64; 2 thread(s)". A mass point is solved with
#           parallel.numberOfThreads = 2 and with 1; the result counts the threads read back from both files.
#
# Author:   Johannes Gerstmayr
# Date:     2026-10-07
#
# Copyright:This file is part of Exudyn. Exudyn is free software. You can redistribute it and/or modify it under the terms of the Exudyn license. See 'LICENSE.txt' for more details.
#
#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

import exudyn as exu
from exudyn.utilities import * #includes itemInterface and rigidBodyUtilities

testIsActive = exu.sys.get('testIsActive', False)

SC = exu.SystemContainer()
mbs = SC.AddSystem()
oMass = mbs.CreateMassPoint(referencePosition=[0,0,0], mass=1, gravity=[0,-9.81,0])
mbs.AddSensor(SensorBody(bodyNumber=oMass, storeInternal=False, fileName='solution/fileHeaderThreadsSensor.txt',
                         outputVariableType=exu.OutputVariableType.Position))
mbs.Assemble()

def ThreadsInHeader(fileName):
    """the number at the end of the version line of a written file"""
    with open(OutputFilePath(fileName), 'r') as file:
        for line in file:
            if line.startswith('#Exudyn version = '):
                return int(line.split(';')[-1].split()[0]) #'... FLOAT64; 2 thread(s)'
    return 0

result = 0
for nThreads in [2, 1]:
    simulationSettings = exu.SimulationSettings()
    simulationSettings.timeIntegration.numberOfSteps = 10
    simulationSettings.timeIntegration.endTime = 0.1
    simulationSettings.timeIntegration.verboseMode = 0
    simulationSettings.parallel.numberOfThreads = nThreads
    simulationSettings.solution.file.name = 'solution/fileHeaderThreadsSolution.txt'
    mbs.SolveDynamic(simulationSettings)

    solutionThreads = ThreadsInHeader('solution/fileHeaderThreadsSolution.txt')
    sensorThreads = ThreadsInHeader('solution/fileHeaderThreadsSensor.txt')
    exu.Print('requested', nThreads, 'threads; solution file:', solutionThreads, ', sensor file:', sensorThreads)
    result += 10*nThreads*(solutionThreads == nThreads) + nThreads*(sensorThreads == nThreads)

exu.Print('solution of fileHeaderThreadsTest=', result) #33 if both files name the threads in both runs
exu.sys['testResult'] = result
```