Viktor T2

from threading import *

def work(i):
    for _ in range(100):
        print(f"hello i'm a thread #{i}")

t1 = Thread(target=work, args=(1,))
t2 = Thread(target=work, args=(2,))
t1.start()
t2.start()
t1.join()
t2.join()

from threading import *

lock = Lock()

def work(i):
    for _ in range(100):
        with lock:
            print(f"hello i'm a thread #{i}")

t1 = Thread(target=work, args=(1,))
t2 = Thread(target=work, args=(2,))
t1.start()
t2.start()
t1.join()
t2.join()

from threading import *
from time import sleep


class GlobalState:
    def __init__(self, x):
        self.x = x
        
    def set_x(self, x):
        self.x = x

def reader(state: GlobalState):
    if state.x % 2 == 0:
        sleep(0.01)  # simulate OS context switch
        print(f"{state.x=} is even")
    else:
        print(f"{state.x=} is odd")
        

def changer(state: GlobalState):
    state.set_x(state.x + 1)

state = GlobalState(2)
t1 = Thread(target=reader, args=(state,))
t2 = Thread(target=changer, args=(state,))
t1.start()
t2.start()
t1.join()
t2.join()

from threading import *
from time import sleep


class GlobalState:
    def __init__(self, x):
        self.x = x
        self.lock = Lock()
        
    def set_x(self, x):
        self.x = x

def reader(state: GlobalState):
    with state.lock:
        if state.x % 2 == 0:
            sleep(0.01)  # simulate OS context switch
            print(f"{state.x=} is even")
        else:
            print(f"{state.x=} is odd")
        

def changer(state: GlobalState):
    with state.lock:
        state.set_x(state.x + 1)

state = GlobalState(2)
t1 = Thread(target=reader, args=(state,))
t2 = Thread(target=changer, args=(state,))
t1.start()
t2.start()
t1.join()
t2.join()

from threading import *
from random import *

class GlobalState:
    def __init__(self):
        self.x = []
        
    def do_something_changing(self):
        if random() < 0.5:
            self.x.append(1)
        elif self.x:
            self.x.pop()

def reader(state: GlobalState):
    for _ in range(10000000):
        if len(state.x) % 2 == 0:
            if len(state.x) % 2 != 0:  # wtf how it's possible?
                print(f"length {len(state.x)} was even before context switch")

def changer(state: GlobalState):
    for _ in range(10000000):
        state.do_something_changing()

state = GlobalState()
t1 = Thread(target=reader, args=(state,))
t2 = Thread(target=changer, args=(state,))
t1.start()
t2.start()
t1.join()
t2.join()