CODEWITHSUNDEEP
pythonmultithreadingpython-2.7python-multithreading
Ravichandra
Ravichandra

Reputation: 2352

parallel threading without waiting for other thread in python

Hi I am trying to run two threads here function1 and function2. I what function1 to run first and while function1 is paused at time.sleep(1000).I expert function2 to start immediately along with function1 and continue it function.

import thread
import time


# Define a function for the thread
def function1( threadName, delay):
    print "%s: %s" % ( threadName, time.ctime(time.time()) )
    time.sleep(1000)

def function2( threadName, delay):
   count = 0
   while count < 5:
      time.sleep(delay)
      count += 1
      print "%s: %s" % ( threadName, time.ctime(time.time()) )


# Create two threads as follows
try:
   thread.start_new_thread( function1, ("Thread-1", 2, ) )
   thread.start_new_thread( function2, ("Thread-2", 4, ) )
except:
   print "Error: unable to start thread"

while True:
    pass

Return

 Thread-1: Tue Sep 22 19:10:03 2015

Upvotes: 0

Views: 1192

Answers (1)

Myk Willis
Myk Willis

Reputation: 12879

You're never going to get truly deterministic scheduling of this nature, but I think the main problem here is probably that when the main thread does

while True:
    pass

it is in a busy wait state, during which it will take virtually all of the available CPU. In Python, even if you have multiple cores on your machine, you'll only see one (non-IO-blocked) thread running at a time.

If you want to launch one or more threads and then wait for them to finish, it's probably easiest to use the higher-level threading interface:

from threading import Thread
t = Thread(target=function1, args=("Thread-1", 2))
# ...
t.join()  # wait for thread to exit

All that being said, your code seems to behave as you are expecting it to on my machine:

C:\Python27\python.exe C:/dev/python/scratch/concurrent.py
Thread-1: Tue Sep 22 13:37:51 2015
Thread-2: Tue Sep 22 13:37:55 2015
Thread-2: Tue Sep 22 13:37:59 2015
Thread-2: Tue Sep 22 13:38:03 2015
Thread-2: Tue Sep 22 13:38:07 2015
Thread-2: Tue Sep 22 13:38:11 2015

Upvotes: 1

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