About 7 min
1. 知识
全局解释器锁GIL
2. 多线程
threading.Thread(target, name, args, daemon, ...)threading.active_count()threading.current_thread()threading.enumerate()
Instance:
.join().start().setDaemon().is_alive()
2.1. 停止flag
一种 stop_threads 变量的方式
import threading
import time
def run():
while True:
time.sleep(0.1)
print('thread running')
if stop_threads:
break
stop_threads = False
t1 = threading.Thread(target=run)
t1.start()
time.sleep(1)
stop_threads = True
t1.join()
print('thread killed')
'''
thread running
thread running
thread running
thread running
thread running
thread running
thread running
thread running
thread running
thread running
thread killed
'''
# -------------------------
import threading
import time
class Dog():
def __init__(self):
self.stop_threads = False
t1 = threading.Thread(target=self.run)
t1.start()
time.sleep(1)
self.stop_threads = True
t1.join()
print('thread killed')
pass
def run(self):
while True:
print('thread running')
if self.stop_threads:
break
dog = Dog()
一种让 stop_threads 变成函数的方式
import threading
import time
def run(stop_threads):
while True:
print('thread running')
if stop_threads():
break
stop_threads = False
# args 只有一个参数时，必须有逗号，不然不是 tuple
t1 = threading.Thread(target=run, args=(lambda: stop_threads,))
t1.start()
time.sleep(1)
stop_threads = True
t1.join()
print('thread killed')
# -----------------------
# 写成类
import threading
import time
def run(stop_threads):
while True:
print('thread running')
if stop_threads():
break
class Dog():
def __init__(self):
self.stop_threads = False
t1 = threading.Thread(target=run, args=(lambda: self.stop_threads,))
t1.start()
time.sleep(1)
self.stop_threads = True
t1.join()
print('thread killed')
pass
dog = Dog()
# ---------------------
# 成员函数
import threading
import time
class Dog():
def __init__(self):
self.stop_threads = False
t1 = threading.Thread(target=self.run, args=(lambda: self.stop_threads,))
t1.start()
time.sleep(1)
self.stop_threads = True
t1.join()
print('thread killed')
pass
def run(self, stop_threads):
while True:
print('thread running')
if stop_threads():
break
dog = Dog()
2.2. 守护线程
设置daemon=True(默认False)会标记其为守护线程。
- 当主进程已经结束后，如果剩下的线程只有守护线程时，守护进程直接退出。
- 当主进程没有结束，那么剩下的线程只有守护线程时，守护进程也不会退出。
比如，我有两个线程，一个read线程一直在print消息，另一个write线程则在input。我们想设置一个退出信号q，让write线程退出后，read线程也跟着退出。
import threading
import time
def read():
i=0
while True:
print(i)
i += 1
time.sleep(1)
def write():
while True:
s = input()
if s=='q':
break
if __name__ == '__main__':
print('test begin...')
tw=threading.Thread(target=write)
tr=threading.Thread(target=read, daemon=True)
tw.start()
tr.start()
for i in range(5):
print('main', i)
time.sleep(1)
'''
# main的5秒后输入q，则主线程已经退出，write线程一退出，read线程立马退出。
(nerf) PS D:\git\gpuhot> & D:/Applications/miniconda/envs/nerf/python.exe d:/git/gpuhot/src/gpuhot/1.py
test begin...
0
main 0
1
main 1
2
main 2
3
main 3
main 4
4
5
6
q7
# main的5秒内输入q，则write线程退出，但主线程还没退出，read线程就仍在跑。
# 当过了5秒，主线程退出后，read线程立马退出。
(nerf) PS D:\git\gpuhot> & D:/Applications/miniconda/envs/nerf/python.exe d:/git/gpuhot/src/gpuhot/1.py
test begin...
0
main 0
1
main 1
q
2
main 2
main 3
3
main 4
4
'''
2.3. join让主进程等待
'''
等待子线程结束后，主线程才继续输出 `'world'`.
'''
import threading
import time
def print666():
time.sleep(5)
print('666')
if __name__ == '__main__':
t = threading.Thread(target=print666)
t.start()
print('hello')
t.join();
print('world')
'''
hello
666
world
'''
'''
陷入死循环。因为主线程在等read结束，而read守护线程只有当主线程结束才自动退出。
'''
import threading
import time
def read():
i=0
while True:
print(i)
i+=1
time.sleep(1)
def write():
while True:
s=input()
if s=='q':
break
if __name__ == '__main__':
print('test begin...')
tw=threading.Thread(target=write)
tr=threading.Thread(target=read, daemon=True)
tw.start()
tr.start()
tr.join()
print('main')
2.4. 内容
列表、对象、字典都是可以保存的
'''
列表
'''
import threading
import time
def get_i_lists(i, i_lists):
i_lists.append(i)
time.sleep(5)
pass
if __name__ == "__main__":
threads = []
i_lists = []
for i in range(10):
t = threading.Thread(target=get_i_lists, args=(i, i_lists))
threads.append(t)
for t in threads:
t.setDaemon(True)
t.start()
print("hello")
for t in threads:
t.join()
print("world")
for i in i_lists:
print(i)
'''
hello
world
0
1
2
3
4
5
6
7
8
9
'''
2.5. 生产者消费者
import queue
import threading
import time
from numpy import mat
def produce(material_queue: queue.Queue, product_queue: queue.Queue):
while material_queue.qsize() > 0:
materail = material_queue.get()
time.sleep(1)
product_queue.put(materail + " producted")
print(
f"name = {threading.current_thread().name}, product_queue's size = {product_queue.qsize()}"
)
def consume(product_queue: queue.Queue):
while True:
product = product_queue.get()
time.sleep(1)
print(
f"name = {threading.current_thread().name}, product_queue's size = {product_queue.qsize()}"
)
material_queue = queue.Queue()
for i in range(10):
material_queue.put("material" + str(i))
product_queue = queue.Queue()
# 几个生产者
for i in range(3):
producer = threading.Thread(target=produce, args=(material_queue, product_queue))
producer.start()
# 几个消费者
for i in range(2):
consumer = threading.Thread(target=consume, args=(product_queue,))
consumer.start()
'''
name = Thread-2 (produce), product_queue's size = 1
name = Thread-3 (produce), product_queue's size = 2
name = Thread-1 (produce), product_queue's size = 2
name = Thread-2 (produce), product_queue's size = 2
name = Thread-3 (produce), product_queue's size = 3
name = Thread-5 (consume), product_queue's size = 4
name = Thread-1 (produce), product_queue's size = 4
name = Thread-4 (consume), product_queue's size = 4
name = Thread-2 (produce), product_queue's size = 3
name = Thread-5 (consume), product_queue's size = 3
name = Thread-4 (consume), product_queue's size = 4
name = Thread-1 (produce), product_queue's size = 4
name = Thread-3 (produce), product_queue's size = 5
name = Thread-5 (consume), product_queue's size = 3
name = Thread-4 (consume), product_queue's size = 3
name = Thread-2 (produce), product_queue's size = 4
name = Thread-5 (consume), product_queue's size = 2
name = Thread-4 (consume), product_queue's size = 2
name = Thread-5 (consume), product_queue's size = 0
name = Thread-4 (consume), product_queue's size = 0
'''
2.6. 锁
'''
没有带锁
'''
import threading
import time
from attr import dataclass
@dataclass
class Accout:
balance: int = 1000
def run(accout: Accout, amount: int):
# 只有这里的sleep，不出问题
# time.sleep(0.1)
if accout.balance >= amount:
# 这里的sleep（耗时操作），就会出问题。因为多个线程都已经通过了if判断，然后都进入了这里，然后都sleep了，然后都减了钱
time.sleep(0.1)
accout.balance -= amount
print(f"balance = {accout.balance}")
else:
print("not enough money")
accout = Accout()
for i in range(2):
t = threading.Thread(target=run, args=(accout, 800))
t.start()
'''
balance = 200
balance = -600
'''
import threading
import time
from attr import dataclass
@dataclass
class Accout:
balance: int = 1000
def run(accout: Accout, amount: int):
with lock:
if accout.balance >= amount:
time.sleep(0.1)
accout.balance -= amount
print(f"balance = {accout.balance}")
else:
print("not enough money")
lock = threading.Lock()
accout = Accout()
for i in range(2):
t = threading.Thread(target=run, args=(accout, 800))
t.start()
'''
balance = 200
not enough money
'''
3. 线程池
- 要么直接提交一个列表，要么依次提交单个元素。
- 要么按列表的提交顺序返回（需要都执行完）；要么按谁先完成的顺序返回（不需要都执行完了）。
'''
线程池
'''
import time
import concurrent.futures
import threading
sleep_time = [ 5, 1, 3, 2, 4, 5, 1, 2, 3, 4 ]
def run(i):
r = sleep_time[i]
time.sleep(r)
print(f"thread {i} start, sleep {r} seconds")
return i
i_list = [ i for i in range(10) ]
with concurrent.futures.ThreadPoolExecutor() as executor:
results = executor.map(run, i_list)
for result in results:
print(result)
print('-'*20)
with concurrent.futures.ThreadPoolExecutor() as executor:
futures = []
for i in range(10):
future = executor.submit(run, i)
futures.append(future)
for future in futures:
print(future.result())
print('-'*20)
with concurrent.futures.ThreadPoolExecutor() as executor:
futures = []
for i in range(10):
future = executor.submit(run, i)
futures.append(future)
# 按谁先完成的顺序重新组织
futures = concurrent.futures.as_completed(futures)
for future in futures:
print(future.result())
'''
thread 1 start, sleep 1 seconds
thread 6 start, sleep 1 seconds
thread 7 start, sleep 2 seconds
thread 3 start, sleep 2 seconds
thread 2 start, sleep 3 seconds
thread 8 start, sleep 3 seconds
thread 9 start, sleep 4 seconds
thread 4 start, sleep 4 seconds
thread 5 start, sleep 5 seconds
thread 0 start, sleep 5 seconds
0
1
2
3
4
5
6
7
8
9
--------------------
thread 6 start, sleep 1 seconds
thread 1 start, sleep 1 seconds
thread 7 start, sleep 2 seconds
thread 3 start, sleep 2 seconds
thread 2 start, sleep 3 seconds
thread 8 start, sleep 3 seconds
thread 4 start, sleep 4 seconds
thread 9 start, sleep 4 seconds
thread 0 start, sleep 5 seconds
thread 5 start, sleep 5 seconds
0
1
2
3
4
5
6
7
8
9
--------------------
thread 6 start, sleep 1 seconds
thread 1 start, sleep 1 seconds
6
1
thread 3 start, sleep 2 seconds
thread 7 start, sleep 2 seconds
3
7
thread 2 start, sleep 3 seconds
thread 8 start, sleep 3 seconds
2
8
thread 9 start, sleep 4 seconds
thread 4 start, sleep 4 seconds
9
4
thread 0 start, sleep 5 seconds
thread 5 start, sleep 5 seconds
0
5
'''
4. 多进程
5. 协程
6. 信号量
