同步调用与异步调用

Posted 2021-01-28 fantsaymwq

提交任务的两种方式：同步调用与异步调用

同步调用

# 同步调用：提交任务后，就在原地等待任务执行完毕，拿到结果，再执行下一行代码.导致程序是串行执行
import time
import random
from concurrent.futures import ThreadPoolExecutor


def work(name):
    print("%s is working" % name)
    time.sleep(random.randint(7, 13))
    res = random.randint(7, 13) * "#"
    return {"name": name, "res": res}


def weigh(job):
    name = job["name"]
    size = len(job["res"])
    print("%s 工作量 <%s>" % (name, size))


if __name__ == "__main__":
    pool = ThreadPoolExecutor(13)    # 人员数目

    job1 = pool.submit(work, "alex").result()
    weigh(job1)
    job2 = pool.submit(work, "jack").result()
    weigh(job2)
    job3 = pool.submit(work, "egon").result()
    weigh(job3)

　　使程序编程串行

异步调用

# 异步调用：提交完任务后，不等待任务执行完毕，
import time
import random
from concurrent.futures import ThreadPoolExecutor


def work(name):
    print("%s is working" % name)
    time.sleep(random.randint(7, 13))
    res = random.randint(7, 13) * "#"
    return {"name": name, "res": res}


def weigh(job):
    job = job.result()
    name = job["name"]
    size = len(job["res"])
    print("%s 工作量 <%s>" % (name, size))


if __name__ == "__main__":
    pool = ThreadPoolExecutor(13)    # 人员数目

    job1 = pool.submit(work, "alex").add_done_callback(weigh)    # pool.submit(work, "alex")这个对象当作结果传给weigh
    job2 = pool.submit(work, "jack").add_done_callback(weigh)
    job3 = pool.submit(work, "egon").add_done_callback(weigh)

阻塞：是进程运行的一种状态，进程运行是碰到I/O就进行阻塞状态，会被剥夺走cpu的执行权限。

同步不同于阻塞，同步：是提交任务的一种方式，如果提交的任务是一个纯计算的同步，没有I/O，提交后要等，没有阻塞。