import threading
def worker():
 """thread worker function"""
 print('Worker')
threads = []
for i in range(5):
 t = threading.Thread(target=worker)
 threads.append(t)
 t.start()

import threading
def worker(num):
 """thread worker function"""
 print('Worker: %s' % num)
threads = []
for i in range(5):
 t = threading.Thread(target=worker, args=(i,))
 threads.append(t)
 t.start()

import threading
import time
def worker():
 print(threading.current_thread().getName(), 'Starting')
 time.sleep(0.2)
 print(threading.current_thread().getName(), 'Exiting')
def my_service():
 print(threading.current_thread().getName(), 'Starting')
 time.sleep(0.3)
 print(threading.current_thread().getName(), 'Exiting')
t = threading.Thread(name='my_service', target=my_service)
w = threading.Thread(name='worker', target=worker)
w2 = threading.Thread(target=worker) # use default name
w.start()
w2.start()
t.start()

import logging
import threading
import time
def worker():
 logging.debug('Starting')
 time.sleep(0.2)
 logging.debug('Exiting')
def my_service():
 logging.debug('Starting')
 time.sleep(0.3)
 logging.debug('Exiting')
logging.basicConfig(
 level=logging.DEBUG,
 format='[%(levelname)s] (%(threadName)-10s) %(message)s',
)
t = threading.Thread(name='my_service', target=my_service)
w = threading.Thread(name='worker', target=worker)
w2 = threading.Thread(target=worker) # use default name
w.start()
w2.start()
t.start()

import threading
import time
import logging
def daemon():
 logging.debug('Starting')
 time.sleep(0.2)
 logging.debug('Exiting')
def non_daemon():
 logging.debug('Starting')
 logging.debug('Exiting')
logging.basicConfig(
 level=logging.DEBUG,
 format='(%(threadName)-10s) %(message)s',
)
d = threading.Thread(name='daemon', target=daemon, daemon=True)
t = threading.Thread(name='non-daemon', target=non_daemon)
d.start()
t.start()

import threading
import time
import logging
def daemon():
 logging.debug('Starting')
 time.sleep(0.2)
 logging.debug('Exiting')
def non_daemon():
 logging.debug('Starting')
 logging.debug('Exiting')
logging.basicConfig(
 level=logging.DEBUG,
 format='(%(threadName)-10s) %(message)s',
)
d = threading.Thread(name='daemon', target=daemon, daemon=True)
t = threading.Thread(name='non-daemon', target=non_daemon)
d.start()
t.start()
d.join()
t.join()

import threading
import time
import logging
def daemon():
 logging.debug('Starting')
 time.sleep(0.2)
 logging.debug('Exiting')
def non_daemon():
 logging.debug('Starting')
 logging.debug('Exiting')
logging.basicConfig(
 level=logging.DEBUG,
 format='(%(threadName)-10s) %(message)s',
)
d = threading.Thread(name='daemon', target=daemon, daemon=True)
t = threading.Thread(name='non-daemon', target=non_daemon)
d.start()
t.start()
d.join(0.1)
print('d.isAlive()', d.isAlive())
t.join()

import random
import threading
import time
import logging
def worker():
 """thread worker function"""
 pause = random.randint(1, 5) / 10
 logging.debug('sleeping %0.2f', pause)
 time.sleep(pause)
 logging.debug('ending')
logging.basicConfig(
 level=logging.DEBUG,
 format='(%(threadName)-10s) %(message)s',
)
for i in range(3):
 t = threading.Thread(target=worker, daemon=True)
 t.start()
main_thread = threading.main_thread()
for t in threading.enumerate():
 if t is main_thread:
 continue
 logging.debug('joining %s', t.getName())
 t.join()

import threading
import logging
class MyThread(threading.Thread):
 def run(self):
 logging.debug('running')
logging.basicConfig(
 level=logging.DEBUG,
 format='(%(threadName)-10s) %(message)s',
)
for i in range(5):
 t = MyThread()
 t.start()

import threading
import logging
class MyThreadWithArgs(threading.Thread):
 def __init__(self, group=None, target=None, name=None,
  args=(), kwargs=None, *, daemon=None):
 super().__init__(group=group, target=target, name=name,
  daemon=daemon)
 self.args = args
 self.kwargs = kwargs
 def run(self):
 logging.debug('running with %s and %s',
  self.args, self.kwargs)
logging.basicConfig(
 level=logging.DEBUG,
 format='(%(threadName)-10s) %(message)s',
)
for i in range(5):
 t = MyThreadWithArgs(args=(i,), kwargs={'a': 'A', 'b': 'B'})
 t.start()

import threading
import time
import logging
def delayed():
 logging.debug('worker running')
logging.basicConfig(
 level=logging.DEBUG,
 format='(%(threadName)-10s) %(message)s',
)
t1 = threading.Timer(0.3, delayed)
t1.setName('t1')
t2 = threading.Timer(0.3, delayed)
t2.setName('t2')
logging.debug('starting timers')
t1.start()
t2.start()
logging.debug('waiting before canceling %s', t2.getName())
time.sleep(0.2)
logging.debug('canceling %s', t2.getName())
t2.cancel()
logging.debug('done')

import logging
import threading
import time
def wait_for_event(e):
 """Wait for the event to be set before doing anything"""
 logging.debug('wait_for_event starting')
 event_is_set = e.wait()
 logging.debug('event set: %s', event_is_set)
def wait_for_event_timeout(e, t):
 """Wait t seconds and then timeout"""
 while not e.is_set():
 logging.debug('wait_for_event_timeout starting')
 event_is_set = e.wait(t)
 logging.debug('event set: %s', event_is_set)
 if event_is_set:
 logging.debug('processing event')
 else:
 logging.debug('doing other work')
logging.basicConfig(
 level=logging.DEBUG,
 format='(%(threadName)-10s) %(message)s',
)
e = threading.Event()
t1 = threading.Thread(
 name='block',
 target=wait_for_event,
 args=(e,),
)
t1.start()
t2 = threading.Thread(
 name='nonblock',
 target=wait_for_event_timeout,
 args=(e, 2),
)
t2.start()
logging.debug('Waiting before calling Event.set()')
time.sleep(0.3)
e.set()
logging.debug('Event is set')

import logging
import random
import threading
import time
class Counter:
 def __init__(self, start=0):
 self.lock = threading.Lock()
 self.value = start
 def increment(self):
 logging.debug('Waiting for lock')
 self.lock.acquire()
 try:
 logging.debug('Acquired lock')
 self.value = self.value + 1
 finally:
 self.lock.release()
def worker(c):
 for i in range(2):
 pause = random.random()
 logging.debug('Sleeping %0.02f', pause)
 time.sleep(pause)
 c.increment()
 logging.debug('Done')
logging.basicConfig(
 level=logging.DEBUG,
 format='(%(threadName)-10s) %(message)s',
)
counter = Counter()
for i in range(2):
 t = threading.Thread(target=worker, args=(counter,))
 t.start()
logging.debug('Waiting for worker threads')
main_thread = threading.main_thread()
for t in threading.enumerate():
 if t is not main_thread:
 t.join()
logging.debug('Counter: %d', counter.value)

import logging
import threading
import time
def lock_holder(lock):
 logging.debug('Starting')
 while True:
 lock.acquire()
 try:
 logging.debug('Holding')
 time.sleep(0.5)
 finally:
 logging.debug('Not holding')
 lock.release()
 time.sleep(0.5)
def worker(lock):
 logging.debug('Starting')
 num_tries = 0
 num_acquires = 0
 while num_acquires < 3:
 time.sleep(0.5)
 logging.debug('Trying to acquire')
 have_it = lock.acquire(0)
 try:
 num_tries += 1
 if have_it:
 logging.debug('Iteration %d: Acquired',
  num_tries)
 num_acquires += 1
 else:
 logging.debug('Iteration %d: Not acquired',
  num_tries)
 finally:
 if have_it:
 lock.release()
 logging.debug('Done after %d iterations', num_tries)
logging.basicConfig(
 level=logging.DEBUG,
 format='(%(threadName)-10s) %(message)s',
)
lock = threading.Lock()
holder = threading.Thread(
 target=lock_holder,
 args=(lock,),
 name='LockHolder',
 daemon=True,
)
holder.start()
worker = threading.Thread(
 target=worker,
 args=(lock,),
 name='Worker',
)
worker.start()

import threading
lock = threading.Lock()
print('First try :', lock.acquire())
print('Second try:', lock.acquire(0))

import threading
lock = threading.RLock()
print('First try :', lock.acquire())
print('Second try:', lock.acquire(0))

import threading
import logging
def worker_with(lock):
 with lock:
 logging.debug('Lock acquired via with')
def worker_no_with(lock):
 lock.acquire()
 try:
 logging.debug('Lock acquired directly')
 finally:
 lock.release()
logging.basicConfig(
 level=logging.DEBUG,
 format='(%(threadName)-10s) %(message)s',
)
lock = threading.Lock()
w = threading.Thread(target=worker_with, args=(lock,))
nw = threading.Thread(target=worker_no_with, args=(lock,))
w.start()
nw.start()

import logging
import threading
import time
def consumer(cond):
 """wait for the condition and use the resource"""
 logging.debug('Starting consumer thread')
 with cond:
 cond.wait()
 logging.debug('Resource is available to consumer')
def producer(cond):
 """set up the resource to be used by the consumer"""
 logging.debug('Starting producer thread')
 with cond:
 logging.debug('Making resource available')
 cond.notifyAll()
logging.basicConfig(
 level=logging.DEBUG,
 format='%(asctime)s (%(threadName)-2s) %(message)s',
)
condition = threading.Condition()
c1 = threading.Thread(name='c1', target=consumer,
  args=(condition,))
c2 = threading.Thread(name='c2', target=consumer,
  args=(condition,))
p = threading.Thread(name='p', target=producer,
  args=(condition,))
c1.start()
time.sleep(0.2)
c2.start()
time.sleep(0.2)
p.start()

import threading
import time
def worker(barrier):
 print(threading.current_thread().name,
 'waiting for barrier with {} others'.format(
 barrier.n_waiting))
 worker_id = barrier.wait()
 print(threading.current_thread().name, 'after barrier',
 worker_id)
NUM_THREADS = 3
barrier = threading.Barrier(NUM_THREADS)
threads = [
 threading.Thread(
 name='worker-%s' % i,
 target=worker,
 args=(barrier,),
 )
 for i in range(NUM_THREADS)
]
for t in threads:
 print(t.name, 'starting')
 t.start()
 time.sleep(0.1)
for t in threads:
 t.join()

import threading
import time
def worker(barrier):
 print(threading.current_thread().name,
 'waiting for barrier with {} others'.format(
 barrier.n_waiting))
 try:
 worker_id = barrier.wait()
 except threading.BrokenBarrierError:
 print(threading.current_thread().name, 'aborting')
 else:
 print(threading.current_thread().name, 'after barrier',
 worker_id)
NUM_THREADS = 3
barrier = threading.Barrier(NUM_THREADS + 1)
threads = [
 threading.Thread(
 name='worker-%s' % i,
 target=worker,
 args=(barrier,),
 )
 for i in range(NUM_THREADS)
]
for t in threads:
 print(t.name, 'starting')
 t.start()
 time.sleep(0.1)
barrier.abort()
for t in threads:
 t.join()

import logging
import threading
import time
class ActivePool:
 def __init__(self):
 super(ActivePool, self).__init__()
 self.active = []
 self.lock = threading.Lock()
 def makeActive(self, name):
 with self.lock:
 self.active.append(name)
 logging.debug('Running: %s', self.active)
 def makeInactive(self, name):
 with self.lock:
 self.active.remove(name)
 logging.debug('Running: %s', self.active)
def worker(s, pool):
 logging.debug('Waiting to join the pool')
 with s:
 name = threading.current_thread().getName()
 pool.makeActive(name)
 time.sleep(0.1)
 pool.makeInactive(name)
logging.basicConfig(
 level=logging.DEBUG,
 format='%(asctime)s (%(threadName)-2s) %(message)s',
)
pool = ActivePool()
s = threading.Semaphore(2)
for i in range(4):
 t = threading.Thread(
 target=worker,
 name=str(i),
 args=(s, pool),
 )
 t.start()

import random
import threading
import logging
def show_value(data):
 try:
 val = data.value
 except AttributeError:
 logging.debug('No value yet')
 else:
 logging.debug('value=%s', val)
def worker(data):
 show_value(data)
 data.value = random.randint(1, 100)
 show_value(data)
logging.basicConfig(
 level=logging.DEBUG,
 format='(%(threadName)-10s) %(message)s',
)
local_data = threading.local()
show_value(local_data)
local_data.value = 1000
show_value(local_data)
for i in range(2):
 t = threading.Thread(target=worker, args=(local_data,))
 t.start()

import random
import threading
import logging
def show_value(data):
 try:
 val = data.value
 except AttributeError:
 logging.debug('No value yet')
 else:
 logging.debug('value=%s', val)
def worker(data):
 show_value(data)
 data.value = random.randint(1, 100)
 show_value(data)
class MyLocal(threading.local):
 def __init__(self, value):
 super().__init__()
 logging.debug('Initializing %r', self)
 self.value = value
logging.basicConfig(
 level=logging.DEBUG,
 format='(%(threadName)-10s) %(message)s',
)
local_data = MyLocal(1000)
show_value(local_data)
for i in range(2):
 t = threading.Thread(target=worker, args=(local_data,))
 t.start()