'NoneType' object has no attribute 'encoding'

[xiuyuan shi]

Hi,
I am a new user of pyomo. When i solve my model using python script "results=opt.solve(instance,tee=True,warmstart=True)", I get "'NoneType' object has no attribute 'encoding'" Error as following. When I use "results=opt.solve(instance)", it return solution status "unkown" without error . But, when I use command line "pyomo --stream-solver --solver=gurobi -c" there is no error and return optimal results.

I do not know what is the problem.  Can anybody help me, thanks a lot.

Exception in thread Thread-2:
Traceback (most recent call last):
  File "C:\Python34\lib\threading.py", line 920, in _bootstrap_inner
    self.run()
  File "C:\Python34\lib\threading.py", line 868, in run
    self._target(*self._args, **self._kwargs)
  File "C:\Python34\lib\site-packages\pyutilib\subprocess\processmngr.py", line 175, in _stream_reader
    encoding = sys.__stdout__.encoding
AttributeError: 'NoneType' object has no attribute 'encoding'
Exception in thread Thread-3:
Traceback (most recent call last):
  File "C:\Python34\lib\threading.py", line 920, in _bootstrap_inner
    self.run()
  File "C:\Python34\lib\threading.py", line 868, in run
    self._target(*self._args, **self._kwargs)
  File "C:\Python34\lib\site-packages\pyutilib\subprocess\processmngr.py", line 175, in _stream_reader
    encoding = sys.__stdout__.encoding
AttributeError: 'NoneType' object has no attribute 'encoding'

[Siirola, John D]

OK, I have an idea of what might be going on here – my guesses are either that you are running within an IDE that is fouling up an assumption in PyUtilib.subprocess, or else a UNICODE issue in python 3.4 that is fouling up the output processing in pyutilib.subprocess when we are streaming output.  By chance, is your computer set up to use a non-ASCII (or non-UTF-8) character set by default (i.e., set up for a non-English locale)?

 

1)      A potential workaround (and this is really a shot in the dark):  try adding the following to the top of your script:

 

import sys

reload(sys)

sys.setdefaultencoding(‘utf-8’)

 

2)      Let’s try actually fixing the root problem…  can you tell us:

a.       what OS?

b.      is your computer set up to run in either a language other than English or a locale other than en_US?

c.       what version of Pyomo (run “pyomo --version” at the command line and share the output)?

d.      are you running in some form of a debugger or IDE?

e.      can you share the script fragment that is running the solver (e.g, the lines starting with “opt = SolverFactory” through the actual call to opt.solve)?

 

Resolving the issue in PyUtilib may take some work (the core PyUtilib developers all develop in the en_US locale, and testing other locales is a bit challenging).

 

john

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[xiuyuan shi]

Dear John,

Thanks a lot for your help. I have tried your suggestions and found it is really the problem of default python IDLE I used. When I switch to other ide like spyder, sublime, no such problem happened. But, still there is a problem that "The solver returned a status of:unknown". I think it should be 'optimal'. Here is the script:

from pyomo.environ import *
from pyomo.opt import SolverFactory,SolverStatus
from pyomo.core import Var

opt=SolverFactory("gurobi")
from CSP import model

instance=model.create_instance('csp.dat')
results=opt.solve(instance,tee=True)
instance.solutions.load_from(results)
print ("The solver returned a status of:"+str(results.Solution.Status))

The OS is Win10, and the locale I changed to en_US. The pyomo version is 4.2.10784.

Best regards

在 2016年2月17日星期三 UTC+8下午12:57:22，John写道：