SYNCHRONIZATION IN PYTHON

The concept of avoiding multiple threads to access the same functionality at a time is known as Synchronization. We can apply synchronization by calling acquire() and release() methods of thread lock.

Example –

import threading
import time
class MyThread(threading.Thread):
    def __init__(self,id,name,count):
        threading.Thread.__init__(self)
        self.id=id
        self.name=name
        self.count=count
    def run(self):
        print 'Starting '+self.name
        threadLock.acquire()
        print_time(self.name,self.count,3)
        threadLock.release()
def print_time(tname,delay,count):
    while count:
        time.sleep(delay)
        print "%s %s "%(tname,time.ctime(time.time()))
        count -=1
threadLock=threading.Lock()
threads = []
thread1=MyThread(1,"Thread1",1)
thread2=MyThread(2,"Thread2",2)
thread1.start()
thread2.start()
threads.append(thread1)
threads.append(thread2)
for i in threads:
    i.join()
print "Exiting thread"

Output –

Starting Thread1

Starting Thread2

Thread1 Tue Feb 07 20:47:03 2017

Thread1 Tue Feb 07 20:47:04 2017

Thread1 Tue Feb 07 20:47:05 2017

Thread2 Tue Feb 07 20:47:07 2017

Thread2 Tue Feb 07 20:47:09 2017

Thread2 Tue Feb 07 20:47:11 2017

Exiting thread

Old Version Multithreading

import thread
import time
def print_time(tname,delay):
    count=0
    while count<5:
        time.sleep(delay)
        count +=1
        print '%s %s '%(tname,time.ctime(time.time()))

try:
    thread.start_new_thread(print_time,("Thread1",2,))
    thread.start_new_thread(print_time,("Thread2",4,))

except:
    print 'Error : Unable to start'

while 1:
    pass

Output –

Thread1 Tue Feb 07 21:02:54 2017

Thread2 Tue Feb 07 21:02:56 2017

Thread1 Tue Feb 07 21:02:56 2017

Thread1 Tue Feb 07 21:02:58 2017

Thread2 Tue Feb 07 21:03:00 2017

Thread1 Tue Feb 07 21:03:01 2017

Thread1 Tue Feb 07 21:03:03 2017

Thread2 Tue Feb 07 21:03:04 2017

Thread2 Tue Feb 07 21:03:09 2017

Thread2 Tue Feb 07 21:03:13 2017