主要用于:回顾和复习以往所学的知识 以及 希望这点经验能够帮助正在学习编程的你
查看线程ID
创建文件 0809.py
- import time
- import threading
-
- def loop():
- while True:
- print('thread id is {}'.format(threading.get_native_id()))
- time.sleep(3)
-
- if __name__ == '__main__':
- loop()
在第一个终端窗口中执行
- $ python 0809.py
- thread id is 3344
- thread id is 3344
- thread id is 3344
- ······
在第二个终端窗口中执行
- ps -ef | grep 'python 0809.py'
- vagrant 3344 3117 0 16:26 pts/1 00:00:00 python 0809.py
- vagrant 3662 3451 0 16:30 pts/0 00:00:00 grep --color=auto python 0809.py
你会发现其进程ID也是 3344和线程ID一致。这是因为Linux中规定,当一个进程中只有一个线程的情况下,线程ID等于进程ID。或则说,进程的第一个线程(主线程)的ID等于进程ID。
经典的生产者/消费者模型(也有人称之为,发布/订阅模型)
- # 0809.py
- import time
- import threading
-
- count = 0
-
- def consumer():
- global count
- while True:
- if count <= 0:
- continue
- count = count - 1
- print(f'count is {count}, consumer thread id is {threading.get_native_id()}')
- time.sleep(2)
-
- def producer():
- global count
- while True:
- count = count + 1
- print(f'count is {count}, producer thread id is {threading.get_native_id()}')
- time.sleep(1)
-
- if __name__ == '__main__':
- tp = threading.Thread(target=producer)
- tc = threading.Thread(target=consumer)
- tp.start()
- tc.start()
执行命令 python 0809.py
- $ python 0809.py
- count is 1, producer thread id is 3785
- count is 0, consumer thread id is 3786
- count is 1, producer thread id is 3785
- count is 0, consumer thread id is 3786
- count is 1, producer thread id is 3785
- count is 2, producer thread id is 3785
- count is 1, consumer thread id is 3786
- count is 2, producer thread id is 3785
可以发现,两个线程并非严格交替执行,而是随机执行。
我们再来查看一下相关的进程和线程
- $ ps -ef | grep 'python 0809.py'
- vagrant 3784 3117 0 17:24 pts/1 00:00:00 python 0809.py
- vagrant 3789 3451 0 17:24 pts/0 00:00:00 grep --color=auto python 0809.py
-
- $ ps -T -p 3784
- PID SPID TTY TIME CMD
- 3784 3784 pts/1 00:00:00 python
- 3784 3785 pts/1 00:00:00 python
- 3784 3786 pts/1 00:00:00 python
可以看出该进程中有三个线程,分别是主线程 3784 和两个子线程 3785(producer)、3786(consumer)
今天我们就先讲到这里,重点掌握:
如何在python代码中和shell终端中查看线程id 进程ID 以及进程中包含的线程。
理解生产/消费者模型,因为这个模型会在接下来的学习中被多次提到