线程/进程锁、池，进程的数据共享

一、线程的锁

线程与进程共有五种锁

首先说说为什么要加锁

1、LOCK与RLOCK锁

import threading
import time

lock=threading.Lock()
def func(args):
    time.sleep(1)
    lock.acquire()
    print(args)
    lock.release()

for i in range(5):
    t=threading.Thread()
    t.start()
    

LOCK 与RLOCK用法相似，RLOCK可以多成加锁，然后多层解锁

2、semaphore 一次放行N个

import threading
import time

lock=threading.BoundedSemaphore(3) #设置一次放行三个进程
def func(args):
    lock.acquire()
    time.sleep(1)
    print(args)
    lock.release()

for i in range(9):
    t=threading.Thread(target=func,args=(i,))
    t.start()

3、Condition 的两种方式

import threading
import time

lock=threading.Condition()
def func(args):
    time.sleep(1)
    lock.acquire()
    lock.wait()
    print(args)
    lock.release()

for i in range(5):
    t=threading.Thread(target=func,args=(i,))
    t.start()

while True:
    inp = int(input("请输入任意数字"))
    lock.acquire()
    lock.notify(inp)
    lock.release()

方式二、

import threading
import time

lock=threading.Condition()
def task():
    input(">>>>")
    return True

def func(args):
    time.sleep(1)
    lock.acquire()
    lock.wait_for(task)
    print(args)
    lock.release()

for i in range(5):
    t=threading.Thread(target=func,args=(i,))
    t.start()

4、Event锁 一次放行所有线程

import threading
import time
lock=threading.Event()
def func(args):
    time.sleep(1)
    lock.wait()
    print(args)

for i in range(5):
    t=threading.Thread(target=func,args=(i,))
    t.start()

input("<<<<")
lock.set()

5、threading.local()原理
为每一个线程创建一个属于自己的内存来存放数据

import threading
import time
v=threading.local()

def func(args):
    v.phone=args  #存放数据
    time.sleep(1)
    print(v.phone,args)

for i in range(5):
    t=threading.Thread(target=func,args=(i,))
    t.start()

6、线程池 设置每次可从线程池中调用的线程数

from concurrent.futures import ThreadPoolExecutor
import threading
import time
pool=ThreadPoolExecutor(2) # 线程池线程的可调用数
def func(args):
    time.sleep(1)
    print(args)

for i in range(5):
    pool.submit(func,i)