Python Programming/Threading

Threading in python is used to run multiple threads (tasks, function calls) at the same time. Note that this does not mean that they are executed on different CPUs. Python threads will NOT make your program faster if it already uses 100 % CPU time. In that case, you probably want to look into parallel programming. If you are interested in parallel programming with python, please see here.

Python threads are used in cases where the execution of a task involves some waiting. One example would be interaction with a service hosted on another computer, such as a webserver. Threading allows python to execute other code while waiting; this is easily simulated with the sleep function.

Make a thread that prints numbers from 1-10 and waits a second between each print:

importthreading
importtime
defloop1_10():
 for i in range(1, 11):
 time.sleep(1)
 print(i)
threading.Thread(target=loop1_10).start()

#!/usr/bin/env python
importthreading
importtime
classMyThread(threading.Thread):
 defrun(self): # Default called function with mythread.start()
 print("{} started!".format(self.getName())) # "Thread-x started!"
 time.sleep(1) # Pretend to work for a second
 print("{} finished!".format(self.getName())) # "Thread-x finished!"
defmain():
 for x in range(4): # Four times...
 mythread = MyThread(name = "Thread-{}".format(x)) # ...Instantiate a thread and pass a unique ID to it
 mythread.start() # ...Start the thread, run method will be invoked
 time.sleep(.9) # ...Wait 0.9 seconds before starting another
if __name__ == '__main__':
 main()

The output looks like this:

Thread-0 started!
Thread-1 started!
Thread-0 finished!
Thread-2 started!
Thread-1 finished!
Thread-3 started!
Thread-2 finished!
Thread-3 finished!

• Book:Python Programming