Threading

Threading#

Sources#

Example1 - runtime messages#

In following exmaple:

  • Define the myThread class as an ancestor of the threading.Thread class - it will describe the behaviour of the thread:

    • The run method is executed when the thread is started - in this case method:

      • Spends time according to the delay parameter of the class;

      • Increases the value of counter by one.

  • Create and run two instances of myThread:

    • With delay 0.5 and 1;

    • With name “first” and “second”;

  • In cycle every 0.5 seconds check is threads still alife and print counter values for each instance;

  • Result:

    • counter of instance named “first” updated at each step;

    • counter of instance named “second” is updated once every two steps.

import threading
import time

steps_count = 5

class myThread(threading.Thread):
    def __init__(self, delay, name):
        super().__init__()
        self.counter = 0
        self.delay = delay
        self.name = name

    def run(self):
        for i in range(steps_count):
            time.sleep(self.delay)
            self.counter += 1

threads = []

# Create new threads
thread1 = myThread(0.5, "first")
thread2 = myThread(1, "second")

begin_time = time.time()
# Start new Threads
thread1.start()
thread2.start()

# Add threads to thread list
threads.append(thread1)
threads.append(thread2)

is_any_thread_live = True
while is_any_thread_live:
    time.sleep(0.5)

    dislpay_line = \
        f"====={round(time.time() - begin_time, 1)}" + \
        " seconds after begining====="
    print(dislpay_line)
    for t in threads:
        print(t.name + " counter = " + str(t.counter))
    
    for t in threads:
        if t.is_alive():
            # if any thread alife
            # i leave the cycle
            break
    else:
        # if we tried all threads
        # and there aren't any alife 
        # set flag for cycle leaving
        is_any_thread_live = False

=====0.5 seconds after begining=====
first counter = 1
second counter = 0
=====1.0 seconds after begining=====
first counter = 2
second counter = 1
=====1.5 seconds after begining=====
first counter = 3
second counter = 1
=====2.0 seconds after begining=====
first counter = 4
second counter = 2
=====2.5 seconds after begining=====
first counter = 5
second counter = 2
=====3.0 seconds after begining=====
first counter = 5
second counter = 3
=====3.5 seconds after begining=====
first counter = 5
second counter = 3
=====4.0 seconds after begining=====
first counter = 5
second counter = 4
=====4.5 seconds after begining=====
first counter = 5
second counter = 4
=====5.0 seconds after begining=====
first counter = 5
second counter = 5
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