parallel.py

import threading
import datetime
import time
import random

class SimpleThreadClass(threading.Thread):
  def run(self):
    for i in range(3):
      now = datetime.datetime.now()
      print("I am: ")
      print(self.getName())
      print("The time is: ")
      print(now)

PrintLock = threading.Lock()

class SafeSimpleThreadClass(threading.Thread):
  def run(self):
    for i in range(3):
      now = datetime.datetime.now()
      PrintLock.acquire(True)
      print("I am: ")
      print(self.getName())
      print("The time is: ")
      print(now)
      PrintLock.release()

def test_threads(t_class, n=2):
  for i in range(n):
    t = t_class()
    t.start()

#test_threads(SimpleThreadClass, 2)

class Philosopher(threading.Thread):
  running = True
  def __init__(self, xname, forkOnLeft, forkOnRight):
    threading.Thread.__init__(self)
    self.name = xname
    self.forkOnLeft = forkOnLeft
    self.forkOnRight = forkOnRight
    self.count = 0

  def safe_print(self, *args):
    PrintLock.acquire()
    print(self.name + ":", *args)
    PrintLock.release()

  def run(self):
    self.safe_print("Hi!")
    while(self.running):  # Philosopher is thinking (but really is sleeping).
      time.sleep(random.uniform(3,13))
      self.safe_print("I'm hungry.")
      self.dine()
    self.safe_print("Ate", self.count, "times.")

  def dine(self):
    fork1, fork2 = self.forkOnLeft, self.forkOnRight
    locked = False
    while self.running:
      fork1.acquire(True)
      locked = fork2.acquire(False)
      if locked:
        break
      fork1.release()
      self.safe_print("Swapping forks")
      fork1, fork2 = fork2, fork1

    if locked:
      self.dining()
      fork2.release()
      fork1.release()


  def dining(self):
    self.safe_print("Starting to eat.")
    self.count += 1
    time.sleep(random.uniform(1,10))
    self.safe_print("Finished eating, leave to think.")


def DiningPhilosophers(t=100, seed=507129):
    forks = [threading.Lock() for i in range(5)]
    names = ('Aristotle', 'Kant', 'Buddha', 'Marx', 'Russel')
    philosophers = [Philosopher(names[i], forks[i%5], forks[(i+1)%5]) for i in range(5)]
    random.seed(seed)
    Philosopher.running = True
    for p in philosophers:
      p.start()
    time.sleep(t)
    Philosopher.running = False
    print("Now we're finishing.")

#DiningPhilosophers()