详解python中Threadpool线程池任务终止示例代码

需求

加入我们需要处理一串个位数（0~9），奇数时需要循环打印它；偶数则等待对应时长并完成所有任务；0则是错误，但不需要终止任务，可以自定义一些处理。

关键点

定义func函数处理需求

callback处理返回结果，只有偶数和0返回；奇数会一直执行；要控制线程池状态，则需要针对偶数和0时抛出异常，并捕获异常处理。

threadpool定义线程池并发

实现

# -*- coding: utf-8 -*-
from threadpool import makeRequests, ThreadPool
import time
from multiprocessing import Process

异常定义和特殊值（0）定义

class Finish(SyntaxWarning):
    pass

class PauseInfo(SyntaxWarning):
    pass
pause_num = 0

func函数定义

0时返回False，其他偶数返回True

def func(para):
    if para == pause_num:
        print('start for %d and wait %ds' % (para, 4))
        time.sleep(4)
        print('error bcs ',para)
        return False
    if para % 2 == 0:
        print('start for %d and wait %ds' % (para, para))
        time.sleep(para)
        print('stop for', para)
        return True
    while True:
        print('continue for', para)
        time.sleep(para)

callback定义

def callback(request, result):
    if result:
        raise Finish
    else:
        raise PauseInfo

线程池处理

Finish标识任务完成，再次诱发异常退出线程池处理；

def main_thread(paras):
    pool = ThreadPool(10)
    requests = makeRequests(callable_=func, args_list=paras, callback=callback)
    [pool.putRequest(req) for req in requests]
    while True:
        try:
            pool.wait()
        except Finish as e:
            raise SystemExit
        except PauseInfo as e:
            print('Pause bcs %d but will continue' % pause_num)
        except Exception as e:
            print('Unknown error so will quit')
            raise SystemExit

主函数起一个测试进程

if name == 'main':
    while True:
        s = input('Input number list to test and any other word to quit\n')
        paras = []
        for para in s:
            if para.isnumeric():
                paras.append(int(para))
            else:
                break
        try:
            thread_test = Process(target=main_thread, args=(paras,))
            thread_test.start()
            thread_test.join(timeout=20)
        except TimeoutError as e:
            print('task timeout')
        except Exception as e:
            print('unknow error:',e)

结果验证

处理108，看打印可以看到，1被循环处理，0处理的时候报错；8处理完毕则任务结束

Input number list to test and any other word to quit
108
continue for 1
start for 0 and wait 4s
start for 8 and wait 8s
continue for 1
continue for 1
continue for 1
error bcs 0
continue for 1
Pause bcs 0 but will continue
continue for 1
continue for 1
continue for 1
continue for 1
stop for 8
Input number list to test and any other word to quit

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