Simulation with Resultfile or Flags Fail to execute

[NilsDressler]

Description

When calling
OMPython.simulaute(resultfile='/home/user/modelica/testfile0.mat')
with a result file (and most likely also with other flags, the following log message is shown

Failed to simulate simulation: [Errno 2] No such file or directory: '/tmp/tmp37u5_obx/Package.Simulation -r=/home/user/modelica/testfile0.mat'

Steps to reproduce

Minimal Example that fails

from os.path import expanduser
from OMPython import ModelicaSystem

home_dir = expanduser("~")

model_path = home_dir + '/modelica/resultfilebug/'
model_file_name = 'BouncingBall.mo'
model_name = 'BouncingBall' 
mod = ModelicaSystem(model_path + model_file_name, model_name )

mod.buildModel()

result_file_path = home_dir + '/modelica/resultfilebug/resultfiles/'
result_file_name = 'resultfile_0.mat'

mod.simulate(resultfile=result_file_path+result_file_name)

Throws followingexception:

Exception has occurred: FileNotFoundError (note: full exception trace is shown but execution is paused at: _run_module_as_main)
[Errno 2] No such file or directory: '/tmp/tmpj5k_1p6k/BouncingBall -r=~/modelica/resultfilebug/resultfiles/resultfile_0.mat'

Even though the file exists in my file system

ls /tmp/tmpqmbz5d57/BouncingBall
/tmp/tmpqmbz5d57/BouncingBall

Running

user@machine:~$ /tmp/tmpqmbz5d57/BouncingBall -r=/home/user/modelica/resultfilebug/resultfiles/resultfile_0.mat

LOG_ASSERT | debug | simulation_input_xml.c: Error: can not read file BouncingBall_init.xml as setup file to the generated simulation code.
Execution failed!

While

user@machine:/tmp/tmpq5rla9at$ ./BouncingBall -r=/home/user/modelica/resultfilebug/resultfiles/resultfile_0.mat

LOG_SUCCESS | info | The initialization finished successfully without homotopy method.
LOG_SUCCESS | info | The simulation finished successfully.

Expected behavior

The model should just build and return the following log messages

LOG_SUCCESS       | info    | The initialization finished successfully without homotopy method.
LOG_SUCCESS       | info    | The simulation finished successfully.

Screenshots

If applicable, add screenshots to help explain your problem.

Version and OS

• Python Version: Python 3.10.12
• OMPython Version: 3.5.1
• OpenModelica Version: 1.22.3
• OS: Windows 11 64 bit - Code run from WSL :Ubuntu 22.04.4 LTS

Additional context

When digging into the problem and debugging I came across this:

The error message suggests that the subprocess is unable to find the executable file /tmp/tmpqmbz5d57/BouncingBall -r=/home/user/modelica/testfile0.mat

The issue here is that the provided cmd is being interpreted as a single command with spaces in its name. Instead, you should separate the executable path and the command-line arguments into separate elements of the cmd list.

So the problem is created within

p = subprocess.Popen(cmd, env=my_env)

A solution to the problem is how cmd is created. If it is a list with

• getExeFile
• override
• csvinput
• r
• simflags

as seperate list entries, it works with my system configuration

[NilsDressler]

I also found a working solution that made the code work for my system.

Before I make a pull request I'm wondering the following.
What format are the simFlags expected to be ?
A long string containing the flags like
mod.simulate(simflags='-flag1 -flag2 -...')
or a list containing the flags as sting
mod.simulate(simflags=['-flag1', '-flag2' '-...'])

I couldn't really find an answer to that in the documentation.
I can make a solution that works for both cases, but that might be unnecessary complicated if just on of them is a valid input.

[InigoGastesi]

Hi, I have the same problem, I have found out that OMPython creates a command like this

cmd = '/tmp/tmpltwurgv3/variable_torque -overrideFile=/tmp/tmpltwurgv3/variable_torque_override.txt -r=variable_torque_size_50.mat'  
subprocess.Popen(cmd)

But doing the following test works nice

import subprocess
cmd = [
    "/tmp/tmpltwurgv3/variable_torque",
    "-overrideFile=/tmp/tmpltwurgv3/variable_torque_override.txt",
    "-r=variable_torque_size_50.mat"
]
p = subprocess.Popen(cmd)

So I suppose that the format of simFlags are like this mod.simulate(simflags=['-flag1', '-flag2' '-...'])

[j-emils]

I have the same problem.

[NilsDressler]

@InigoGastesi
Yes this was also the solution i found and how i fixed i in the commit i made.
If you give the subprocess a python list containing the path to the executable at index 0 and then all the flags in the subsequent indices, it works. Compared to the current implementation you only have to remove the initial blank space from the flags.

[InigoGastesi]

@NilsDressler I using your commit now in my project, thank you

[arun3688]

@NilsDressler the issue is fixed with this commit fa56e30 and thanks for @NilsDressler for fixing the issue

[InigoGastesi]

Hi @arun3688, I think that this issue is not fixed in that commit. In that commit the only think that is fixed is the problem with the subprocess

[arun3688]

@InigoGastesi Yes that is true, but still the issue fixes the subprocess problem in linux.
@NilsDressler It is not allowed to provide result file path in the simulate() API, you can only provide the name for the result file and the result file will always be generated in the temp directory. see the docs here https://openmodelica.org/doc/OpenModelicaUsersGuide/1.22/ompython.html#simulation

The model can be simulated using the simulate API in the following ways,

1. without any arguments
2. resultfile (keyword argument) - (only filename is allowed and not the location)
3. simflags (keyword argument) - runtime simulationflags supported by OpenModelica

An example of how to use the simflags is also provided in the documentation

[InigoGastesi]

@arun3688 I'm checking your last comment and in the following code

filename = f'{model_name}_size_{size}'
print(filename) # voltage_torqueVariable_size_50
mod.simulate(resultfile=f'{filename}.mat') #Para simular el modelo, empleo el método ".simulate()"

I have this error

[Errno 2] No such file or directory: '/tmp/tmp9y_av4ml/voltage_torqueVariable -overrideFile=/tmp/tmp9y_av4ml/voltage_torqueVariable_override.txt -r=voltage_torqueVariable_size_50.mat'

I checked it and the file exists. Also, I tried do the same without .mat extension and the same problem appears. As you can see in the print there is only filename

[arun3688]

@InigoGastesi what happens if you directly use mod.simulate(resultfile="voltage_torqueVariable_size_50.mat")

[InigoGastesi]

Same error :(

[arun3688]

@InigoGastesi strange what happens if you just run mod.simulate()