TimeOut in

[somnath chakrabarti]

Hi Python Tutor members,

 

I have a requirement where I am trying to give a solution for Magic Square puzzle for sizes ranging from 3 to 5 and using different Solvers. I have the below MS class derived from Problem class which is defined in constraint.py. The Problem class has a method called getSolution() which I am overriding in derived class MS. In MS.getSolution(solver), I am trying to start a threading.Timer object that will execute MS.onTimeout() method when time exceeds 100 secs i.e. if there is delay more than 100 secs for the Problem.getSolution() method, the timer thread will execute onTimeout and cancel the timer thread.

Once the timer thread is canceled, the control must return back to the magic_square(n,solver=BacktrackingSolver()) function at the control point ms.p.join() and it would print the time taken. Finally, it will close the thread in magic_square.

 

Below is the code that I have written to do the timeout implementation. But I am getting error as follows. Can anybody please help me where I am going wrong?

 

%%%%%%Error Message %%%%%%%%%%%%%%%%%%%%%%%%%%%

 

Traceback (most recent call last):
  File "C:\Users\Somnath\Documents\NetBeansProjects\CSC671\src\csc671.py", line 125, in <module>
<constraint.BacktrackingSolver object at 0x02845F50>
    ms_t.magic_square(size,func_solver())
Magic Square:
None
  File "C:\Users\Somnath\Documents\NetBeansProjects\CSC671\src\ms_t.py", line 65, in magic_square
    print ms.getSolution(solver)
 Time Exceeded Limit.None

Time Exceeded Limit.
  File "C:\Users\Somnath\Documents\NetBeansProjects\CSC671\src\ms_t.py", line 39, in getSolution
    self.p = threading.Timer(100, self.onTimeout())
  File "C:\Users\Somnath\Documents\NetBeansProjects\CSC671\src\ms_t.py", line 52, in onTimeout
    if self.p.isAlive():
AttributeError: 'MS' object has no attribute 'p'
Exception in thread Thread-1:
Traceback (most recent call last):
  File "C:\Python26\lib\threading.py", line 525, in __bootstrap_inner
    self.run()
  File "C:\Python26\lib\threading.py", line 477, in run
    self.__target(*self.__args, **self.__kwargs)
  File "C:\Users\Somnath\Documents\NetBeansProjects\CSC671\src\ms_t.py", line 39, in getSolution
    self.p = threading.Timer(100, self.onTimeout())
  File "C:\Users\Somnath\Documents\NetBeansProjects\CSC671\src\ms_t.py", line 52, in onTimeout
    if self.p.isAlive():
AttributeError: 'MS' object has no attribute 'p'

 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

 

Below is the code -->

 

 

from __future__ import generators
from constraint import *
import time
#import thread
import threading
#import sys
#import signal
global t

class MS(Problem):
    start = 0
    end = 0
    def __init__(self,solver=None,size=3):
        Problem.__init__(self,solver)
        Problem.addVariables(self,range(0,size*size),range(1,size*size+1))
        self.addConstraints(size)
        self.solution = {}
    def addConstraints(self,size):
        magic_sum = (size*(size*size + 1))/2
        Problem.addConstraint(self,AllDifferentConstraint(),range(0,size*size))
        Problem.addConstraint(self,ExactSumConstraint(magic_sum),[i for i in range(0,size*size,size+1)])
        Problem.addConstraint(self,ExactSumConstraint(magic_sum),[i for i in range(size-1,size*(size-1)+1,size-1)])
        for row in range(size):
            Problem.addConstraint(self,ExactSumConstraint(magic_sum),[row*size+i for i in range(size)])
        for col in range(size):
            Problem.addConstraint(self,ExactSumConstraint(magic_sum),[col+size*i for i in range(size)])
    def getSolution(self,solver):
        Problem.setSolver(self,solver)
        self.p = threading.Timer(100, self.onTimeout())
        self.start=time.time()
        self.p.start()
        try:
            self.solution=Problem.getSolution(self)
        finally:
            self.end=time.time()
        self.p.cancel()
    # dummy signal handler for timeout
    def onTimeout(self):
        print None
        print 'Time Exceeded Limit.'
        if self.p.isAlive():
            self.p.cancel()

 

def magic_square(n,solver=BacktrackingSolver()):
        ms=MS(solver,n)
        print solver
        print 'Magic Square:'
        t = threading.Thread(None,ms.getSolution,None,(solver,),{})
        t.start()
        print ms.getSolution(solver)
        ms.p.join()
        print 'Time taken: %1.3f' % (ms.end-ms.start)
        t.cancel()

 

--
Thanks and regards,
Somnath Chakrabarti.

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[Alan Gauld]

"somnath chakrabarti" <chakrabarti.somnath@...> wrote

> Below is the code that I have written to do the timeout implementation.
> But
> I am getting error as follows. Can anybody please help me where I am
> going
> wrong?

I have no idea how this framework is upposed to work but my
guess is that the problem lies here:

>    def getSolution(self,solver):
>        Problem.setSolver(self,solver)
>        self.p = threading.Timer(100, self.onTimeout())

Thios looks like you should be providing a callback
function self.onTimeout but you are calling the function
instead of referencing it. This calls the method before
self.p has been defined.

You need to remove the parentheses after Timeout.

I think...

--
Alan Gauld
Author of the Learn to Program web site
http://www.alan-g.me.uk/ 


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[somnath chakrabarti]

Hi Alan,

 

I am importing the constraint library package in the beginning that is having classes Problem, Solver and all the methods that I am calling. Now, as you said after making the change from 

 

        self.p = threading.Timer(100, self.onTimeout)

 

I am getting the below error. I am also attaching the constraint.py package that my code is using

 

- Somnath

 

 

%%%%%%% Error Message %%%%%%%%%%%%%%%%%%%%

 

<constraint.BacktrackingSolver object at 0x02846F10>
Magic Square:
Exception in thread Thread-1:
Traceback (most recent call last):
  File "C:\Python26\lib\threading.py", line 525, in __bootstrap_inner
    self.run()
  File "C:\Python26\lib\threading.py", line 477, in run
    self.__target(*self.__args, **self.__kwargs)
  File "C:\Users\Somnath\Documents\NetBeansProjects\CSC671\src\ms_t.py", line 43, in getSolution
    self.solution=Problem.getSolution(self)
  File "C:\Users\Somnath\Documents\NetBeansProjects\CSC671\src\constraint.py", line 215, in getSolution
    return self._solver.getSolution(domains, constraints, vconstraints)
  File "C:\Users\Somnath\Documents\NetBeansProjects\CSC671\src\constraint.py", line 524, in getSolution
    return iter.next()
  File "C:\Users\Somnath\Documents\NetBeansProjects\CSC671\src\constraint.py", line 506, in getSolutionIter
    pushdomains):
  File "C:\Users\Somnath\Documents\NetBeansProjects\CSC671\src\constraint.py", line 1173, in __call__
    domain.hideValue(value)
  File "C:\Users\Somnath\Documents\NetBeansProjects\CSC671\src\constraint.py", line 787, in hideValue
    list.remove(self, value)
ValueError: list.remove(x): x not in list
None
Time taken: 0.047

Traceback (most recent call last):
  File "C:\Users\Somnath\Documents\NetBeansProjects\CSC671\src\csc671.py", line 125, in <module>
    ms_t.magic_square(size,func_solver())
  File "C:\Users\Somnath\Documents\NetBeansProjects\CSC671\src\ms_t.py", line 68, in magic_square
    t.cancel()
AttributeError: 'Thread' object has no attribute 'cancel'
None
Time Exceeded Limit.

On Sun, Nov 8, 2009 at 12:17 PM, Alan Gauld <alan.gauld@...> wrote:

"somnath chakrabarti" <chakrabarti.somnath@...> wrote

Below is the code that I have written to do the timeout implementation. But
I am getting error as follows. Can anybody please help me where I am going
wrong?

I have no idea how this framework is upposed to work but my
guess is that the problem lies here:

  def getSolution(self,solver):
      Problem.setSolver(self,solver)
      self.p = threading.Timer(100, self.onTimeout())

Thios looks like you should be providing a callback
function self.onTimeout but you are calling the function
instead of referencing it. This calls the method before
self.p has been defined.

You need to remove the parentheses after Timeout.

I think...

--
Alan Gauld
Author of the Learn to Program web site
http://www.alan-g.me.uk/

_______________________________________________
Tutor maillist  -  Tutor@...
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--
Thanks and regards,
Somnath Chakrabarti.


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[OkaMthembo]

Hi Somnath,

I think the exception simply means that the thread object or class does not have a cancel function. maybe read docs on Python threads to see what functions can be called on those?

On Sun, Nov 8, 2009 at 9:09 PM, somnath chakrabarti <chakrabarti.somnath@...> wrote:

Hi Alan,

 

I am importing the constraint library package in the beginning that is having classes Problem, Solver and all the methods that I am calling. Now, as you said after making the change from 

 

        self.p = threading.Timer(100, self.onTimeout)

 

I am getting the below error. I am also attaching the constraint.py package that my code is using

 

- Somnath

 

 

%%%%%%% Error Message %%%%%%%%%%%%%%%%%%%%

 

<constraint.BacktrackingSolver object at 0x02846F10>
Magic Square:

Exception in thread Thread-1:
Traceback (most recent call last):
  File "C:\Python26\lib\threading.py", line 525, in __bootstrap_inner
    self.run()
  File "C:\Python26\lib\threading.py", line 477, in run
    self.__target(*self.__args, **self.__kwargs)

  File "C:\Users\Somnath\Documents\NetBeansProjects\CSC671\src\ms_t.py", line 43, in getSolution

    self.solution=Problem.getSolution(self)

  File "C:\Users\Somnath\Documents\NetBeansProjects\CSC671\src\constraint.py", line 215, in getSolution
    return self._solver.getSolution(domains, constraints, vconstraints)
  File "C:\Users\Somnath\Documents\NetBeansProjects\CSC671\src\constraint.py", line 524, in getSolution
    return iter.next()
  File "C:\Users\Somnath\Documents\NetBeansProjects\CSC671\src\constraint.py", line 506, in getSolutionIter
    pushdomains):
  File "C:\Users\Somnath\Documents\NetBeansProjects\CSC671\src\constraint.py", line 1173, in __call__
    domain.hideValue(value)
  File "C:\Users\Somnath\Documents\NetBeansProjects\CSC671\src\constraint.py", line 787, in hideValue
    list.remove(self, value)
ValueError: list.remove(x): x not in list
None
Time taken: 0.047

Traceback (most recent call last):
  File "C:\Users\Somnath\Documents\NetBeansProjects\CSC671\src\csc671.py", line 125, in <module>

    ms_t.magic_square(size,func_solver())

  File "C:\Users\Somnath\Documents\NetBeansProjects\CSC671\src\ms_t.py", line 68, in magic_square
    t.cancel()
AttributeError: 'Thread' object has no attribute 'cancel'
None
Time Exceeded Limit.

On Sun, Nov 8, 2009 at 12:17 PM, Alan Gauld <alan.gauld@...> wrote:

"somnath chakrabarti" <chakrabarti.somnath@...> wrote

Below is the code that I have written to do the timeout implementation. But
I am getting error as follows. Can anybody please help me where I am going
wrong?

I have no idea how this framework is upposed to work but my
guess is that the problem lies here:

  def getSolution(self,solver):
      Problem.setSolver(self,solver)
      self.p = threading.Timer(100, self.onTimeout())

Thios looks like you should be providing a callback
function self.onTimeout but you are calling the function
instead of referencing it. This calls the method before
self.p has been defined.

You need to remove the parentheses after Timeout.

I think...

--
Alan Gauld
Author of the Learn to Program web site
http://www.alan-g.me.uk/

_______________________________________________
Tutor maillist  -  Tutor@...
To unsubscribe or change subscription options:
http://mail.python.org/mailman/listinfo/tutor

--
Thanks and regards,
Somnath Chakrabarti.

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To unsubscribe or change subscription options:
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--
Regards,
Lloyd

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