I’m having trouble using python’s multiprocessing module. This is the first time I’ve tried using the module. I’ve tried simplifying my processing to the bare bones, but keep getting the same error. I’m using python 2.7.2, and Windows 7.
The script I’m trying to run is called learnmp.py, and the error message says that the problem is that it can't find module learnmp.
import multiprocessing
def doSomething():
"""worker function"""
print 'something'
return
if __name__ == '__main__':
jobs = []
for i in range(2):
p = multiprocessing.Process(target=doSomething)
jobs.append(p)
p.start()
The error is :
File “<string>”, line 1, in <module> File “C:\Python27\ArcGISx6410.1\lib\multiprocessing\forking.py”, line 373,
in main prepare(preparation_data) File “C:\Python27\ArcGISx6410.1\lib\multiprocessing\forking.py”, line 482,
in prepare file, path_name, etc = imp.find_module (main_name, dirs)
ImportError: No module named learnmp
What’s causing the error, and how can I solve it?
EDIT: I still don't know what was causing the error, but changing the file name eliminated it.
I know it's been a while, but I ran into this same error, also using the version of Python distributed with ArcGIS, and I've found a solution which at least worked in my case.
The problem that I had was that I was calling my program name, Test.py, as test.py. Note the difference in case.
c:\python27\arcgisx6410.2\python.exe c:\temp\test.py
c:\python27\arcgisx6410.2\python.exe c:\temp\Test.py
This isn't normally an issue if you're not using the multiprocessing library. However, when you write:
if __name__ == '__main__':
what appears to be happening is that the part of the program in main is being bound to the name of the python file. In my case that was test. However, there is no test, just Test. So although Windows will allow case-incorrect filenames in cmd, PowerShell, and in batch files, Python's multiprocessing library balks at this and throws a nasty series of errors.
Hopefully this helps someone.
Looks like you might be going down a rabbit-hole looking into multiprocessing. As the traceback shows, your python install is trying to look in the ArcGIS version of python before actually looking at your system install.
My guess is that the version of python that ships with ArcGIS is slightly customized for some reason or another and can't find your python script. The question then becomes:
Why is your Windows machine looking in ArcGIS for python?
Without looking at your machine at a slightly lower level I can't quite be sure, but if I had to guess, you probably added the ArcGIS directory to your PATH variable in front of the standard python directory, so it looks in ArcGIS first. If you move the ArcGIS path to the end of your PATH variable it should resolve the problem.
Changing your PATH variable: http://www.computerhope.com/issues/ch000549.htm
Microsoft Visual C++ 9.0 is required for some python modules to work in windows,so download below package it will work.
http://aka.ms/vcpython27
This package contains the compiler and set of system headers necessary for producing binary wheels for Python 2.7 packages.
Related
I am new with programming, so it is maybe harder for me to understand but I have the following issue:
I have a script that imports "eurostag.dll", which according to its manual, should work until Python 3.6. (but the manual is not updated, so it may work also with later updates, I assume).\ The issue is that I have Python 3.8. and when running the script I receive the following message:
"Failed to load EUROSTAG library (Could not find module 'D:\Eurostag\eustag_esg.dll' (or one of its dependencies). Try using the full path with constructor syntax.)"
I have tried to move the .dll library where the script is, but nothing changed. I tried also changing the directory with os.chdir, but the same message appears (with the same 'D:\Eurostag\eustag_esg.dll', so the directory was not changed.
Does anybody know if there is any workaround for this?
Thank you!
So I am trying to write some python code that will do two things, that seem to be mutually exclusive on my machine. My PC's host operating system is windows and I run Kali-Linux in WSL2 when I need to test my code on Linux. My code's main function creates two separate multiprocessing.Process objects, assigning a different thread, starting them both one after the other and then calling for them both to be joined. The plan is to allow each to run a simple server application simultaneously on different ports. This does not work when running python3 in PowerShell, as it seems to require access to os.fork() which doesn't work in said environment. When I found this out I pivoted to running in WSL2 which worked fantastically, for a time. After a while of experimenting with some ideas I decided to take some of my code and spin it off into its own file, which I placed in its own 'Libs' folder. WSL2 however, was unable to import this new file, instead giving me the exception ModuleNotFoundError: No module named 'NetStuff'. I originally had added:
sys.path.append('./Libs')
as has worked for me in the past, however when I found that WSL2 was unable to find my module, I printed out sys.path and it revealed that rather than appending my $current_working_directory/Libs like I intended, I was just appending the literal string, which wasn't useful. I then decided to try:
sys.path.append(str(pathlib.Path().resolve()) + '/Libs')
which at the bare minimum shows up as I would expect in sys.path. This, however still didn't work, python was unable to find my module and would unceremoniously crash every time. This led me to try something else, I ran my code in python3 under PowerShell again, which had no issue importing my module, it did still crash due to lacking os.fork() but the import gave no issues. Confused and annoyed I opened my code in IDLE 3.9 which, for some inexplicable reason, was able to import the file, and seemingly use os.fork(). The only major issue with running in IDLE is that it is seemingly incapable of understanding ascii colour escape characters. Given that the goal is to run my code in bash, and ideally also PowerShell, I am not satisfied with this as a solution. I returned to trying to fix the issue in WSL2 by adding my module to /home/Noah/bin, and appending this directory to sys.path, but this has still not so much as given me a new symptom.
I am utterly at a loss at this point. none of the fixes I know off hand are working, and neither are the new ones I've found online. I can't tell if I'm just missing something fundamental about python or if I'm running into a bug, if it's the latter, i can't seem to find other people with the same issue. As a result of my confusion and frustration I am appealing to you, kind users of stackoverflow.
The following is the snippet that is causing me problems in WSL2:
path0 = ('/home/Noah/bin')
path1 = (str(pathlib.Path().resolve()) + '/Libs')
sys.path.append(path0)
sys.path.append(path1)
print(sys.path)
import NetStuff
The following is output of print(sys.path) in WSL2:
['/mnt/c/Users/Noah/VSCodeRepos/Python/BlackPack', '/usr/lib/python39.zip', '/usr/lib/python3.9', '/usr/lib/python3.9/lib-dynload', '/home/noah/.local/lib/python3.9/site-packages', '/usr/local/lib/python3.9/dist-packages', '/usr/lib/python3/dist-packages', '/home/Noah/bin', '/mnt/c/Users/Noah/VSCodeRepos/Python/BlackPack/Libs']
The following is the error being thrown by WSL2:
Traceback (most recent call last):
File "/mnt/c/Users/Noah/VSCodeRepos/Python/BlackPack/BlackPackServer.py", line 21, in <module>
import NetStuff
ModuleNotFoundError: No module named 'NetStuff'
I am specifically hoping to fix the issue with WSL2 at the moment as I am fairly certain that getting the code to run on PowerShell is merely going to require rewriting my code so that it doesn't rely on os.fork(). Thank you for reading my problem, and if I left out any information that you would like to see just tell me and I'll add it in an edit!
Edit: I instantly realized that I should specify that my host machine is running windows 10.
module path lost in multiprocessing spawn (ModuleNotFoundError)
The so-called solution of inserting sys-path above the importing of the module does not work for me.
Here is my main.py
import multiprocessing
from testing import customfunction
customfunction(1,2,3)
if __name__ == "__main__":
process = multiprocessing.Process(target=customfunction)
process.start()
process.join()
print("DONE")
The main.py works fine up to process.start()
This means customfunction has been imported properly
Here is my testing.py
import random
def customfunction(size, test, hello):
random.seed(size)
print(random.random())
return random.random()
Both main.py and testing.py are in the same folder. A separate folder with an init.py file did not work as well.
I get this error:
from testing import customfunction
ModuleNotFoundError: No module named 'testing'
I can not wrap my head around why does the process created not retain the system pathing in order to import the file. If i place the multiprocessing creation in customfunction it doesn't work either, the same error occurs.
The link I shared at the top does not work for me as well.
Thank you for taking the time to read. If you believe this is a duplicate of another question, please link it and explain, I am new to python.
EDIT:
I am using Windows 10 as my OS
I have installed Spyder 4.1.4 using Anaconda Navigator, Python 3.7.7.
I installed using a executable package.
I have tested this code on VS Code as well.
I am running this via the two IDEs mentioned(E.G VS Code Powershell console and Spyder's Python Console by clicking run)
I generally currently believe it is an issue specific to my computer, and I'll like to know if its replicable in other Windows Systems and whether or not the linked "solution" in the first line works. With that I may be able to pinpoint my errors
This should work if you invoke multiprocessing.Process(target=customfunction, args=(1,2,3)) instead. I can't think of a reason why this would not work on Linux.
Can you update your question and provide the following information?
What OS are you using?
What version of Python are you running, and how was it installed?
How are you running main.py (e.g. from the command line, from an IDE, etc.)?
Any other details about your system configuration that might help others answer your question?
No multiprocessing print outputs (Spyder)
The solution mentioned here seems to solve my problem, I never expected either VS Code or Spyder's Console to have an issue with multiprocessing, but running the code in an external system terminal works.
Thank you to Melih Elibol for helping me think more clearly about the problem, I am new to python.
I am attempting to use the PyMultinest package. The full error text I am encountering is AttributeError:dlsym(RTLD_DEFAULT, run): symbol not found in the __getitem__() function in ctypes/__init__.py. I'll include more text and code below, but I am mostly trying to understand what this error is telling me - my Google Fu is apparently lacking, and the StackExchange questions I have seen relating to this error seem to be hyper-focused on solving a specific instance of this error. So - What is this error trying to tell me is wrong?
More context. I attempt to execute the PyMultinest (PMN) package as directed in the PMN documentation. PMN is, effectively, a Python wrapper for a C program. Running PMN requires a fair bit of setup code (several ancillary functions need to be defined, as well as a host of variables), which I'm not including here by default because it's ... a lot, but I can if needed. The PMN execution line I use is
pmn.run(Loglike, Prior, ndims, n_live_points=1000, n_params=n_params, outputfiles_basename='./'+ProjectName+'/temp_', resume=False, verbose=True)
This returns the error traceback
File "[redacted]", line 139, in <module>
pmn.run(Loglike, Prior, ndims, n_live_points=1000, n_params=n_params, outputfiles_basename='./'+ProjectName+'/temp_', resume=False, verbose=True)
File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/pymultinest/run.py", line 254, in run
lib.run(*args_converted)
File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/ctypes/__init__.py", line 386, in __getattr__
func = self.__getitem__(name)
File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/ctypes/__init__.py", line 386, in __getitem__
func = self._FuncPtr((name_or_ordinal, self))
AttributeError: dlsym(RTLD_DEFAULT, run): symbol not found
If it helps, I have determined that the name variable being passeed through self.__getitem__(), and thus into self._FuncPtr(), is run. Although, that might be obvious looking at the AttributeError message.
I am running Python 3.8 (as shown above) on a MacOS machine. Last summer, I was able to execute PMN on this machine using extremely similar code to that which I am using now. I am currently trying to optimize my code from last summer, which is why I'm surprised it isn't simply "working".
So far my attempts at fixing this have been mostly centered on reinstalling PMN. I have done a clean install (pip uninstall/pip install) of the PMN package, as well as following the PMN documentation to rebuild the C portion of the package. I have included the source directories of the C software in my Path variables - or at least, I tried to, I am assuming I was successful, but I'm not very familiar with Macs.
Ultimately, I just wish I understood what Python was telling me with this error better. It would help me direct my own attempts at solving the issue. I suspect it is saying "We don't know where to find this 'run' command you're asking for," in which case I need to figure out why my Path variable changes aren't working. Am I on the right path?
Some hints how to resolve this are given in these issues:
https://github.com/JohannesBuchner/PyMultiNest/issues/160
https://github.com/JohannesBuchner/PyMultiNest/issues/163
It is important to cleanly recompile (empty build folder) when the environment changes, so that cmake recognises changed libraries and compilers.
Check if you are running everything with python3 and not python (works as python 2.x is you have both version 2 and 3 installed)
Check is all the PyMultiNest python files are rewritten in python 3 style, e.g. $ print "something" becomes $ print("something")
My supervisor was accidentally running on python 2.7 and got the same error, so your error might as well be due to mismatch of python version usages.
Run command flutter pub cache clean and flutter clean and after that run flutter pub get now relaunch your emulator it worked for me.
I am currently learning Python and I work on a project where I need a launcher to launch a series of the same script.
So, I have the launcher calling my other script, and I need the second script to import modules for it to work. But then I get the infamous ModuleNotFound: no module named "". When I launch the file myself, it works properly as intended and the module is found.
LAUNCHER
i=0
while i<1000:
print('Creating file number '+str(i)+'')
os.system('C:\\Users\\Gauthier\\Desktop\\file.py')
time.sleep(int(frequency))
print('File number '+str(i)+' created')
i+=1
I guess that must be a miscomprehension on my side, but after reading tens of questions on stackeoverflow and other forums, the official documentation and some tutorials, I can't find the proper way to import a module in a script which is itself launched by another file.
As file.py requests data from APIs, I cannot just read the script with
exec(open('file.py').read())
because I need multiple instances of the same script to be launched at the same time.
I am sorry if I missed something obvious, but it's been days -- I've uninstalled Python multiple times, tried a lot of different ways to call a file from another-- but I finally came here to ask for help.
Thanks!
I simple work around could be that you can add the path in
sys.path.append('/usr/lib64/python2.7/')
sys.path.append('<path to your modules>')
and then import your packages.
A similar statement can be used as many times and can be used to import your modules as well.