[PyQt] SSH port forwarding and connection to SQL Server in separate threads freezes

[jan_pips]

Below full code

import pymssql
import sqlalchemy as ORM

class dbhMSSQL(object):
    def __init__(self, config):
        self.dialect = "mssql"
        self.driver = "pymssql"
        self.username = "parameter provided from GUI"
        self.password = "parameter provided from GUI"
        self.host = "host"
        self.port = "port"
        self.database = "database"
 
    def engine_create(self):
        self.conn_string = "{0}+{1}://{2}:{3}@{4}:{5}/{6}".format(self.dialect, self.driver, self.username, self.password, self.host, self.port, self.database)
        self.engine = ORM.create_engine(self.conn_string)
 
    def connection_check(self):
        try:
            dbc_main = self.engine.connect()
            result = self.engine.execute(
                "SELECT * FROM sys.dm_exec_connections"
            ).fetchall()
            dbc_main.close()
            return True
        except Exception as ex:
            return False