PyQt5 - Threading

[reginald]

I need help in implementing a worker thread in the code of an app I wrote. The app takes and search user inputs in a SQL db - everything works, but the GUI tends to freeze (Not responding) during long queries, hence the need to implement threading. I have looked at several examples but can't figure out how to apply them to my code. Any help would be appreciated.

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#!/usr/bin/env python   import pyodbc import sys   from PyQt5.QtWidgets import QMainWindow, QApplication, QTableWidgetItem, QMessageBox from PyQt5.QtGui import QRegExpValidator from PyQt5.QtCore import QRegExp from PyQt5 import uic   from ui_pysearch import Ui_pySearch   class pySearchMain(QMainWindow):     def __init__(self):         QMainWindow.__init__(self)         self.ui = Ui_pySearch()         self.ui.setupUi(self)         self.ui.tableWidget_ResultsIncident.setHorizontalHeaderLabels(["A", "B", "C"])         self.ui.tableWidget_ResultsCompany.setHorizontalHeaderLabels(["A", "B", "C"])           self._set_validators()         self.ui.Button_Search.clicked.connect(self._save_pushed)       def _set_validators(self):         reg_ex = QRegExp(r"[A-Za-z0-9]{0,6}")         val_company_custid = QRegExpValidator(reg_ex, self.ui.Input_lineEdit_CompanyPIN)         self.ui.Input_lineEdit_CompanyPIN.setValidator(val_company_custid)           reg_ex = QRegExp(r"[A-Za-z ]{0,25}")         val_company_name = QRegExpValidator(reg_ex, self.ui.Input_lineEdit_CompanyName)         self.ui.Input_lineEdit_CompanyName.setValidator(val_company_name)           reg_ex = QRegExp(r"[A-Za-z ]{0,25}")         val_incident_service = QRegExpValidator(reg_ex, self.ui.Input_lineEdit_IncidentService)         self.ui.Input_lineEdit_IncidentService.setValidator(val_incident_service)       def _save_pushed(self):           self.ui.tableWidget_ResultsIncident.clearContents()         self.ui.tableWidget_ResultsCompany.clearContents()           Company_CustID = self.ui.Input_lineEdit_CompanyPIN.text()         Company_Name = self.ui.Input_lineEdit_CompanyName.text()         Incident_Service = self.ui.Input_lineEdit_IncidentService.text()           Set_Company_RecID = set()         Set_Company_CustID = set()         Set_Company_CustID_Substring = set()         Set_Company_Name = set()         Set_Company_Name_Substring = set()         Set_IncidentNumber_CompanyName = set()         Set_IncidentNumber_Service = set()           Match_Input_lineEdit = 1         Match_RecID_CompanyCustID = -1         Match_RecID_CompanyName = -1           if len(str(Company_CustID)) == 6:             with pyodbc.connect('DRIVER={ODBC Driver 17 for SQL Server};SERVER=ServerIP;DATABASE=Sqldbname;UID=db_username;PWD=db_password') as DB_Connect:                 SearchCursor = DB_Connect.cursor()                 SearchCursor.execute("select RecId, CustID, Name from Company")                 for row in SearchCursor.fetchall():                     if str(row[1]).lower() == str(Company_CustID).lower():                         Match_RecID_CompanyCustID = row[0]                         Set_Company_RecID.add(str(row[1]))         if len(str(Company_CustID)) > 1:             with pyodbc.connect('DRIVER={ODBC Driver 17 for SQL Server};SERVER=ServerIP;DATABASE=Sqldbname;UID=db_username;PWD=db_password') as DB_Connect:                 SearchCursor = DB_Connect.cursor()                 SearchCursor.execute("select RecId, CustID, Name from Company")                 for row in SearchCursor.fetchall():                     if str(row[1]).lower().rfind(str(Company_CustID).lower()) != -1:                         Set_Company_CustID_Substring.add(row[0])                         Set_Company_RecID.add(str(row[1]))         if len(str(Company_Name)) > 2:             with pyodbc.connect('DRIVER={ODBC Driver 17 for SQL Server};SERVER=ServerIP;DATABASE=Sqldbname;UID=db_username;PWD=db_password') as DB_Connect:                 SearchCursor = DB_Connect.cursor()                 SearchCursor.execute("select RecId, CustID, Name from Company")                 for row in SearchCursor.fetchall():                     if str(row[2]).lower() == str(Company_Name).lower():                         Match_RecID_CompanyName = row[0]                         Set_Company_RecID.add(str(row[1]))                     if str(row[2]).lower().rfind(str(Company_Name).lower()) != -1:                         Set_Company_Name_Substring.add(row[0])                         Set_Company_RecID.add(str(row[1]))         if Match_RecID_CompanyCustID != -1:             with pyodbc.connect('DRIVER={ODBC Driver 17 for SQL Server};SERVER=ServerIP;DATABASE=Sqldbname;UID=db_username;PWD=db_password') as DB_Connect:                 SearchCursor = DB_Connect.cursor()                 SearchCursor.execute("select IncidentNumber from Incident")                 for row in SearchCursor.fetchall():                     if row[0] == Match_RecID_CompanyCustID:                         Set_Company_CustID.add(int(row[0]))         if Match_RecID_CompanyName != -1:             with pyodbc.connect('DRIVER={ODBC Driver 17 for SQL Server};SERVER=ServerIP;DATABASE=Sqldbname;UID=db_username;PWD=db_password') as DB_Connect:                 SearchCursor = DB_Connect.cursor()                 SearchCursor.execute("select IncidentNumber, CompanyLink_RecID from Incident")                 for row in SearchCursor.fetchall():                     if row[1] == Match_RecID_CompanyName:                         Set_Company_Name.add(int(row[0]))         if len(str(Company_Name)) > 2:             with pyodbc.connect('DRIVER={ODBC Driver 17 for SQL Server};SERVER=ServerIP;DATABASE=Sqldbname;UID=db_username;PWD=db_password') as DB_Connect:                 SearchCursor = DB_Connect.cursor()                 SearchCursor.execute("select IncidentNumber, CompanyName from Incident")                 for row in SearchCursor.fetchall():                     if str(row[1]).lower() == str(Company_Name).lower():                         Set_IncidentNumber_CompanyName.add(int(row[0]))                     if str(row[1]).lower().rfind(str(Company_Name).lower()) != -1:                         Set_IncidentNumber_CompanyName.add(int(row[0]))         if len(Incident_Service) > 2:             with pyodbc.connect('DRIVER={ODBC Driver 17 for SQL Server};SERVER=ServerIP;DATABASE=Sqldbname;UID=db_username;PWD=db_password') as DB_Connect:                 SearchCursor = DB_Connect.cursor()                 SearchCursor.execute("select IncidentNumber, Service from Incident")                 for row in SearchCursor.fetchall():                     if (row[1].lower()).rfind(Incident_Service.lower()) != -1:                         Set_IncidentNumber_Service.add(int(row[0]))         if len(Set_Company_CustID_Substring) != 0:             with pyodbc.connect('DRIVER={ODBC Driver 17 for SQL Server};SERVER=ServerIP;DATABASE=Sqldbname;UID=db_username;PWD=db_password') as DB_Connect:                 SearchCursor = DB_Connect.cursor()                 SearchCursor.execute("select IncidentNumber, CompanyLink_RecID from Incident")                 for row in SearchCursor.fetchall():                     for Set_Company_CustID_Substring_Item in Set_Company_CustID_Substring:                         if row[1] == Set_Company_CustID_Substring_Item:                             Set_Company_CustID.add(int(row[0]))         if len(Set_Company_Name_Substring) != 0:             with pyodbc.connect('DRIVER={ODBC Driver 17 for SQL Server};SERVER=ServerIP;DATABASE=Sqldbname;UID=db_username;PWD=db_password') as DB_Connect:                 SearchCursor = DB_Connect.cursor()                 SearchCursor.execute("select IncidentNumber, CompanyLink_RecID from Incident")                 for row in SearchCursor.fetchall():                     for Set_Company_Name_Substring_Item in Set_Company_Name_Substring:                         if row[1] == Set_Company_Name_Substring_Item:                             Set_Company_Name.add(int(row[0]))             if len(Set_Company_CustID) == 0 and len(Company_CustID) != 0:             Match_Input_lineEdit = 0         if len(Set_Company_Name) == 0 and len(Company_Name) != 0:             Match_Input_lineEdit = 0         if len(Set_IncidentNumber_Service) == 0 and len(Incident_Service) != 0:             Match_Input_lineEdit = 0         if len(Set_IncidentNumber_CompanyName) == 0 and len(Company_Name) != 0:             Match_Input_lineEdit = 0             Match_Input_lineEdit = 0         if Match_Input_lineEdit == 0:             alert = QMessageBox()             alert.setText('No results')             self.ui.tableWidget_ResultsIncident.clearContents()             self.ui.tableWidget_ResultsIncident.setRowCount(0)             alert.exec_()             return         List_Of_All_Sets = [Set_Company_CustID, Set_Company_Name, Set_IncidentNumber_Service, Set_IncidentNumber_CompanyName]           try:             Set_Intersection = set.intersection(*(s for s in List_Of_All_Sets if s))             if len(Set_Intersection) == 0:                 alert = QMessageBox()                 alert.setText('No results')                 self.ui.tableWidget_ResultsIncident.clearContents()                 self.ui.tableWidget_ResultsIncident.setRowCount(0)                 alert.exec_()         except TypeError:             alert = QMessageBox()             alert.setText('No results')             self.ui.tableWidget_ResultsIncident.clearContents()             self.ui.tableWidget_ResultsIncident.setRowCount(0)             alert.exec_()         else:             if self.ui.radioButton_Search_Incident.isChecked():                 self.ui.tableWidget_ResultsIncident.setRowCount(0)                 tableWidget_ResultsIncident_row_num = self.ui.tableWidget_ResultsIncident.rowCount()                 with pyodbc.connect(                     'DRIVER={ODBC Driver 17 for SQL Server};SERVER=ServerIP;DATABASE=Sqldbname;UID=db_username;PWD=db_password') as DB_Connect:                     Set_Intersection_Cursor = DB_Connect.cursor()                       Set_Intersection_Cursor.execute("select CompanyLink_RecID, IncidentNumber from Incident")                     for Set_Intersection_Cursor_Incident_Item in Set_Intersection_Cursor.fetchall():                         for Set_Intersection_Item in Set_Intersection:                             if Set_Intersection_Cursor_Incident_Item[1] == Set_Intersection_Item:                                 Match_Intersection_RecID = Set_Intersection_Cursor_Incident_Item[0]                                   Set_Intersection_Cursor.execute("select RecId, CustID, Name from Company")                                 for Set_Intersection_Cursor_Company_Item in Set_Intersection_Cursor.fetchall():                                     if Set_Intersection_Cursor_Company_Item[0] == Match_Intersection_RecID:                                         self.ui.tableWidget_ResultsIncident.insertRow(tableWidget_ResultsIncident_row_num)                                         self.ui.tableWidget_ResultsIncident.setItem(tableWidget_ResultsIncident_row_num, 0, QTableWidgetItem(str(Set_Intersection_Item)))                                         self.ui.tableWidget_ResultsIncident.setItem(tableWidget_ResultsIncident_row_num, 1, QTableWidgetItem(str(Set_Intersection_Cursor_Company_Item[1])))                                           Set_Intersection_Cursor.execute("select IncidentNumber, Priority, Service, TypeOfIncident, CellNum, CreatedDateTime, Status, TACPrime, Owner from Incident")                                         for row in Set_Intersection_Cursor.fetchall():                                             if row[0] == Set_Intersection_Item:                                                 self.ui.tableWidget_ResultsIncident.setItem(tableWidget_ResultsIncident_row_num, 2, QTableWidgetItem(str(row[1]))) #Priority                                             if row[0] == Set_Intersection_Item:                                                 self.ui.tableWidget_ResultsIncident.setItem(tableWidget_ResultsIncident_row_num, 3, QTableWidgetItem(str(row[2]))) #Service               if len(Set_Company_RecID) != 0 and self.ui.radioButton_Search_Company.isChecked():                 self.ui.tableWidget_ResultsCompany.setColumnWidth(0, 215)                 self.ui.tableWidget_ResultsCompany.setColumnWidth(1, 215)                 self.ui.tableWidget_ResultsCompany.setColumnWidth(2, 215)                   self.ui.tableWidget_ResultsCompany.setRowCount(0)                 tableWidget_ResultsCompany_row_num = self.ui.tableWidget_ResultsCompany.rowCount()                 with pyodbc.connect(                     'DRIVER={ODBC Driver 17 for SQL Server};SERVER=ServerIP;DATABASE=Sqldbname;UID=db_username;PWD=db_password') as DB_Connect:                     Company_RecID_Cursor = DB_Connect.cursor()                       Company_RecID_Cursor.execute("select RecID, CustID, Name from Company")                     for Company_RecID_Cursor_Item in Company_RecID_Cursor.fetchall():                         for Set_Company_RecID_Item in Set_Company_RecID:                             if Company_RecID_Cursor_Item[1] == Set_Company_RecID_Item:                                 self.ui.tableWidget_ResultsCompany.insertRow(tableWidget_ResultsCompany_row_num)                                 self.ui.tableWidget_ResultsCompany.setItem(tableWidget_ResultsCompany_row_num, 0, QTableWidgetItem(str(Set_Company_RecID_Item)))                                 self.ui.tableWidget_ResultsCompany.setItem(tableWidget_ResultsCompany_row_num, 1, QTableWidgetItem(str(Company_RecID_Cursor_Item[2])))                                 self.ui.tableWidget_ResultsCompany.setItem(tableWidget_ResultsCompany_row_num, 2, QTableWidgetItem(str(Company_RecID_Cursor_Item[0])))   if __name__ == '__main__':     app = QApplication(sys.argv)     main = pySearchMain()     main.show()     sys.exit(app.exec_())

[deanhystad]

What exactly do you want to run in a separate thread? Is it already in it's own function?

[reginald]

For additional context: The current UI consists of a QMainWindow with QLineEdit boxes for inputs and a QPushButton to initiate the search. I'm looking to add a progress bar (and a cancel button) alongside the worker thread - As it is now, _set_validators grabs the user input and _save_pushed searches the db (Lines 39-130) and displays the results (Lines 166-211) in a QTabWidget object (within the QMainWindow). So I supposes these two sets of codes are the ones I need to run a separate thread(s) to prevent the GUI from hanging.

[deanhystad]

To run in a separate thread you will need 1 function that will do all the work. It should grab all the values it needs, maybe disable the pushbutton, draw the progress bar and cancel button, perform all the work, erase the progress bar and cancel button, and enable the pushbutton. In the simplified example below this is the "thread_func". The "button_func" is the function that is called when the button is pressed.

Things may be as simple as:

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def thread_func(a1, a2, a3):     Disable pushbutton     Draw progress bar and cancel button     Call functions that do the work     Erase the progress bar and cancel button     Enable pushbutton   def button_func():     x = threading.Thread(target=thread_func, args=(a1, 2, a3))  # Whatever args to pass     x.start

The cancel button would set some flag that the processing code would monitor. You can kill a thread, but it is better to let the application exit gracefully. The worker code will also have to update the progress bar periodically.