Python & Tkinter -> About calling a long running f

Question

Am a new in GUI programming and I am trying to make a GUI for one of my python parser.

I know that :

• Tkinter is single threaded. Screen updates happen on each trip through the event loop. Any time you have a long running command you are preventing the event loop from completing an iteration, thus preventing the processing of events, thus preventing redraws.

• My program call a big function that takes about 5 minutes to be ran entirely. So I guess the only solution is tu use thread for the long running command. BUT, my long running command in already threaded so I don't really know how to proceed.

--> As soon as I click on BUT1 in the GUI, the program freeze until the function is entirely done. I'd like to run this function in the backgroung, so the program will not freeze.

--> I'm not looking for a complete solution but if someone can put me on a good track, it will be wonderful !

• Main.py -> The GUI
• Module_1.py -> The function that we call by clicking on the button BUT1

Thank you in advance !

Here is Main.py --> the GUI

#!/usr/bin/python
# -*- coding: utf-8 -*-


from Tkinter import *
import sys
import tkMessageBox
import tkFileDialog
import Module_1
import csv

from time import strftime, gmtime
DATE = strftime("_%d_%b_%Y")


class App:

    def __init__(self, master):

        self.frame = Frame(master, borderwidth=5, relief=RIDGE)
        self.frame.grid()

        class IORedirector(object):
            def __init__(self,TEXT_INFO):
                self.TEXT_INFO = TEXT_INFO

        class StdoutRedirector(IORedirector):
            def write(self,str):
                self.TEXT_INFO.config(text=self.TEXT_INFO.cget('text') + str)


        self.TEXT_HEADER = self.text_intro = Label(self.frame, bg="lightblue",text="THIS IS \n MY SUPER PROGRAM") 
        self.TEXT_HEADER.grid(row=0, column=0, columnspan=2, sticky=W+E+N+S)

        self.MENU = Frame(self.frame, borderwidth=5, relief=RIDGE, height=12) 
        self.MENU.grid(row=1, column=0, sticky=N)

        self.button = Button(self.MENU, text="QUIT", bg="red", command=self.frame.quit)
        self.button.grid(row=4, column=0)

        self.BUT1 = Button(self.MENU, text="BUT1", command=self.BUT1)
        self.BUT1.grid(row=0, column=0,sticky=W+E)



        self.TEXT_INFO = Label(self.frame, height=12, width=40, text="SOME TEXT", bg="grey",borderwidth=5, relief=RIDGE)
        self.TEXT_INFO.grid(row=1, column=1, sticky = N+W)

        sys.stdout = StdoutRedirector(self.TEXT_INFO)


    def BUT1(self):
        self.BUT1.config(text="RUNNING") 
        self.TEXT_INFO.config(text="BUT1 LAUNCHED")

        Module_1.main("BUT1")
        ## HERE WE NEED TO RUN THE FUNCTION
        ## THE PROGRAMM FREEZE HERE UNTIL THE FUNCTION IS ENTIRELY RUN

        self.TEXT_INFO.config(text="BUT1 FINISHED")
        self.BUT1.config(text="DONE")


root = Tk()
app = App(root)

root.mainloop()

And here is Module_1.py --> contain the big function

#!/usr/bin/python
# -*- coding: utf-8 -*-

import Queue
import threading
import urllib2
import time
from bs4 import BeautifulSoup as soup
from urllib2 import urlopen
import re
import os
import random
import sys
import logging
import csv
from time import strftime, gmtime
import os
import random
import shutil
import sys
import re
import logging
from threading import RLock
from time import strftime, gmtime
import csv
import urllib
from urllib import urlretrieve
from grab.spider import Spider, Task

logging.basicConfig(level=logging.CRITICAL) # Loggin to DEBUG / INFO
log = logging.getLogger()

DATE = strftime("_%d_%b_%Y")


class SPIDER1(Spider):
    initial_urls = ['URL_THAT_I_NEED_TO_PARSE']

    def __init__(self):
        super(SPIDER1, self).__init__(
            thread_number=20,
            network_try_limit=20,
            task_try_limit=20
        )
        self.result = {}

    def task_initial(self, grab, task):
        for opt in grab.css_list("select[name='Template$TestCentreSearch1$SubRegionList'] option")[1:]:
            grab.set_input('Template$TestCentreSearch1$SubRegionList', opt.attrib['value'])
            grab.submit(extra_post={
                '__EVENTTARGET': 'Template$TestCentreSearch1$SubRegionList'
            }, make_request=False)
            yield Task('parse', grab=grab, country=opt.text_content())

    def task_parse(self, grab, task):
        log.info('downloaded %s' % task.country)
        city_gen = (x.text_content() for x in grab.css_list(".TestCentreSearchLabel+br+span"))
        title_gen = (x.text_content() for x in grab.css_list(".TestCentreSearchTitle"))
        id_gen = (x.attrib['href'][-36:] for x in grab.css_list(".TestCentreSearchLink"))
        for x in zip(city_gen, title_gen, id_gen):
            self.result[x[2]] = {
                'country': task.country,
                'city': x[0],
                'name': x[1],
                'id': x[2],
                'price':'',
                'currency':'',
                'fee':''
            }
            yield Task('info', 'URL_URL=%s' % x[2], id=x[2])

    def task_info(self, grab, task):
        for label in grab.css_list(".TestCentreViewLabel"):
            if label.text_content().strip()=="Test Fee:":
                fees = label.getnext().text_content().strip()
                self.result[task.id]['fee'] = fees
                price = re.findall('\d[\d\., ]+\d',fees)
                if price:
                    price = re.findall('\d[\d\., ]+\d',fees)[0]
                    self.result[task.id]['price'] = price.replace(' ','').replace(',','.')
                    currency = re.findall('[A-Z]{2,3}[$|€|£]?',fees)
                    if not currency:
                        currency = re.findall('[$|€|£]',fees)
                        if not currency:
                            currency = fees.replace(price,'').strip().replace('  ','')
                    if isinstance(currency,list):
                        currency = currency[0]
                    self.result[task.id]['currency'] = currency
                #log.info('      %(price)s   %(currency)s     -   %(fee)s ' % self.result[task.id])
                break


    def dump(self, path):
        """
        Save result as csv into the path
        """
        with open(path, 'w') as file:
            file.write("ID;Country;State;City;Name;Price;Currency;Original Fee\n")
            for test_center in sorted(self.result.values(), key=lambda x: "%(country)s%(city)s%(name)s" % x):
                file.write(("%(id)s;%(country)s;;%(country)s;%(name)s;%(price)s;%(currency)s;%(fee)s\n" % test_center).encode('utf8'))


def main(choice):
    parser, path, name = None, None, None

    def run(name,parser,path):
        log.info('Parsing %s...' % name)
        parser.run()
        parser.dump(path)
        log.info('Parsing %s completed, data was dumped into %s' % (name, path))
        log.info(parser.render_stats())


    if choice == "NONE":
        # DO NOTHING
        # HERE I'D LIKE TO HAVE ANOTHER CALL TO ANOTHER THREADED FUNCTION

    elif choice == "BUT1":
        run('Function1',SPIDER1(),'C:\LOL\Output1'+DATE+'.csv')

So by clicking on BUT1, we run the main("BUT1") function contained in the Module_1.py file with argument BUT1 that launch -> run('Function1',SPIDER1(),'C:\LOL\Output1'+DATE+'.csv') And then the program freeze until the parser has finished is work .. :)

Answer 1

The problem is simple: BUT1 won't return until the call to main returns. As long as main (and thus, BUT1) doesn't return, your GUI will be frozen.

For this to work you must put main in a separate thread. It's not sufficient that main spawns other threads if all it's doing is waiting for those threads.

Answer 2

If you call root.update() occasionally from the BUT1 function, that should prevent the GUI from freezing. You could also do that from a python thread with a fixed interval.

For example, updating every 0.1 seconds:

from threading import Thread
from time import sleep

self.updateGUIThread = Thread(target=self.updateGUI)

def updateGUI(self):
    while self.updateNeeded
        root.update()
        sleep(0.1)

After the big function completes you can set self.updateNeeded to False.