Why does my python script with sleep in infinite loop stop running?

Question

I'm working on a python script to transfer data from an .xlsx file to a html: I read/parse the excel with pandas and use beautifulsoup to edit the html (reading the paths to these two files from two .txt's). This, on its own, works. However, this script has to run constantly so everything is called in an infinite while that loops every 15 minutes, each time messages being displayed on the console.

My problem is the following: for some reason, after an aleatoric number of loops, the code just doesn't run anymore, and by that I mean no text on the console and no changes in the html file. When this happens, I have to rerun it in order to get it to function again.

Here is the main function:

def mainFunction():
    if getattr(sys, 'frozen', False):
        application_path = os.path.dirname(sys.executable)
    elif __file__:
        application_path = os.path.dirname(__file__)

    excelFiles = open(str(application_path) +"\\pathsToExcels.txt")
    htmlFiles = open(str(application_path) +"\\pathsToHTMLs.txt")
    sheetFiles = open(str(application_path) +"\\sheetNames.txt")

    print("Reading file paths ...")
    linesEx = excelFiles.readlines()
    linesHtml = htmlFiles.readlines()
    linesSheet = sheetFiles.readlines()

    print("Begining transfer")
    for i in range (len(linesEx)):
        excel = linesEx[i].strip()
        html = linesHtml[i].strip()
        sheet = linesSheet[i].strip()

        print("Transfering data for " + sheet)
        updater = UpdateHtml(excel, sheet, str(application_path) + "\\pageTemplate.html", html)
        updater.refreshTable()
        updater.addData()
        updater.saveHtml()

    print("Transfer done")
    excelFiles.close()
    htmlFiles.close()
    sheetFiles.close()

UpdateHtml is the one actually responsible for the data transfer.

The "__main__" which also contains the while loop:

if __name__ == "__main__":
    while(True):
        print("Update at " + str(datetime.now()))
        mainFunction()
        print("Next update in 15 minutes\n")
        time.sleep(900)

And finally, the batch code that launches this

python "C:\Users\Me\PythonScripts\excelToHtmlTransfer.py"

pause

From what I've noticed through trials, this situation doesn't occur when sleep is set to under 5 minutes (still happens for 5 minutes) or if it's omitted altogether.

Does anyone have any clue why this might be happening? Or any alternatives to sleep in this context?

EDIT: UpdateHtml:

import pandas as pd
from bs4 import BeautifulSoup

class UpdateHtml:
    def __init__(self, pathToExcel, sheetName, pathToHtml, pathToFinalHtml):
        with open(pathToHtml, "r") as htmlFile:
            self.soup = BeautifulSoup(htmlFile.read(), features="html.parser")
        self.df = pd.read_excel (pathToExcel, sheet_name=sheetName)
        self.html = pathToFinalHtml
        self.sheet = sheetName
    
    def refreshTable(self):
       #deletes the inner html of all table cells
        for i in range(0, 9):
            td = self.soup.find(id = 'ok' + str(i))
            td.string = ''
            td = self.soup.find(id = 'acc' + str(i))
            td.string = ''
            td = self.soup.find(id = 'nok' + str(i))
            td.string = ''
            td = self.soup.find(id = 'problem' + str(i))
            td.string = '' 

    def prepareData(self):
        #changes the names of columns according to their data
        counter = 0
        column_names = {}
        for column in self.df.columns: 
            if 'OK' == str(self.df[column].values[6]):
                column_names[self.df.columns[counter]]  = 'ok'
            elif 'Acumulate' == str(self.df[column].values[6]):
                column_names[self.df.columns[counter]]  = 'acc'
            elif 'NOK' == str(self.df[column].values[6]):
                column_names[self.df.columns[counter]]  = 'nok'
            elif 'Problem Description' == str(self.df[column].values[7]):
                column_names[self.df.columns[counter]]  = 'prob'
            counter += 1
            
        self.df.rename(columns = column_names, inplace=True)

    def saveHtml(self):
        with open(self.html, "w") as htmlFile:
            htmlFile.write(self.soup.prettify())
    
    def addData(self):
        groupCounter = 0
        index = 0

        self.prepareData()

        for i in range(8, 40):
            #Check if we have a valid value in the ok column
            if pd.notna(self.df['ok'].values[i]) and str(self.df['ok'].values[i]) != "0":
                td = self.soup.find(id = 'ok' + str(index))
                td.string = str(self.df['ok'].values[i])
            #Check if we have a valid value in the accumulate column
            if pd.notna(self.df['acc'].values[i]) and str(self.df['acc'].values[i]) != "0":
                td = self.soup.find(id = 'acc' + str(index))
                td.string = str(self.df['acc'].values[i])
            #Check if we have a valid value in the nok column
            if pd.notna(self.df['nok'].values[i]) and str(self.df['nok'].values[i]) != "0":
                td = self.soup.find(id = 'nok' + str(index))
                td.string = str(self.df['nok'].values[i])
            #Check if we have a valid value in the problem column
            if pd.notna(self.df['prob'].values[i]):
                td = self.soup.find(id = 'problem' + str(index))
                td.string = str(self.df['prob'].values[i])
            if groupCounter == 3:
                index += 1
                groupCounter = 0
            else:
                groupCounter += 1

The excel I'm working with is a bit strange hence why I perform so many (seemingly) redundant operations. Still, it has to remain in its current form. The main thing is the fact that the 'rows' that contain data is actually formed out of 4 regular rows, hence the need for groupCounter .

Answer 1

Found a workaround for this problem. Basically what I did was move the loop in the batch script, as so:

:whileLoop
python "C:\Users\Me\PythonScripts\excelToHtmlTransfer.py"
timeout /t 900 /nobreak
goto :whileLoop

After leaving it to run for a few hours the situation didn't occur anymore, however unfortunately I still don't know what caused it.