| #File: synchmultithread.py
#Using locks for synchronization in a multithreaded script import sys import cx_Oracle import threading from xml.dom.minidom import parseString from urllib import urlopen #subclass of threading.Thread class SynchThread(threading.Thread): def __init__(self, cur, query, dom): threading.Thread.__init__(self) self.cur = cur self.query = query[1] self.tag = query[0] self.dom = dom def run(self): self.cur.execute(self.query) rslt = self.cur.fetchone()[0] self.cur.close() mutex.acquire() sal = self.dom.getElementsByTagName('salary')[0] newtag = self.dom.createElement(self.tag) newtext = self.dom.createTextNode('%s'%rslt) newtag.appendChild(newtext) sal.appendChild(newtag) mutex.release() #main thread starts here domdoc = parseString(' dbconn = cx_Oracle.connect('hr', 'hr', '127.0.0.1/XE',threaded=True) mutex = threading.Lock() queries = {} queries['avg'] = "SELECT AVG(salary) FROM employees" queries['max'] = "SELECT MAX(salary) FROM employees" th = [] for i, query in enumerate(queries.items()): cur = dbconn.cursor() th.append(SynchThread(cur, query, domdoc)) th[i].start() #forcing the main thread to wait until all child threads are done for t in th: t.join() #printing out the result xml document domdoc.writexml(sys.stdout) |
