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进程创建启动
python提供了multiprocessing模块来支持多进程
multiprocessing.Process(targettask, args(arg,))用于创建进程
Process类相关方法
start() 启动进程join() 等待进程结束
启动子线程
【注意】线程启动代码块要放在__name__ __main__下
方式…并发编程-进程
进程创建启动
python提供了multiprocessing模块来支持多进程
multiprocessing.Process(targettask, args(arg,))用于创建进程
Process类相关方法
start() 启动进程join() 等待进程结束
启动子线程
【注意】线程启动代码块要放在__name__ __main__下
方式一
import multiprocessing
import timedef task(name: str, count: int):print(f{name} - step 1\n, end)result 0for i in range(count):result i 1time.sleep(5)print(f{name}- end with {result})def start_process1():name p1count 100process multiprocessing.Process(targettask, args(name, count))process.start()process.join()print(main process over)if __name__ __main__:start_process1()运行结果
PS F:\Code\python_code\high_python\python_advance\multiprocesses python .\multiprocesses_demo.py
p1 - step 1
p1- end with 5050
main process over查看进程信息一条进程是python用来做资源监控的所以有两条。
PS F:\Code\python_code\high_python tasklist.exe|findstr python
python.exe 19588 Console 2 11,436 K
python.exe 14300 Console 2 11,644 K方式二
import multiprocessing
import timedef task(name: str, count: int):print(f{name} - step 1\n, end)result 0for i in range(count):result i 1time.sleep(5)print(f{name}- end with {result})def statr_process2():args_list [(a, 100), (b, 99), (c, 98)]processes [multiprocessing.Process(targettask, args(name, count)) for name, count in args_list]for p in processes:p.start()for p in processes:p.join()# 创建进程
if __name__ __main__:statr_process2()运行结果
PS F:\Code\python_code\high_python\python_advance\multiprocesses python .\multiprocesses_demo.py
a - step 1
b - step 1
c - step 1
a- end with 5050
b- end with 4950
c- end with 4851检查进程信息
PS F:\Code\python_code\high_python tasklist.exe|findstr python
python.exe 15016 Console 2 11,576 K
python.exe 13820 Console 2 11,520 K
python.exe 3676 Console 2 11,632 K
python.exe 3080 Console 2 11,624 K进程池
进程的创建和销毁比起线程更加耗费资源频繁的创建和销毁线程对系统的性能影响更大进程池是python提供的便于进程管理和提高性能的工具
使用进程池
python提供了两个类concurrent.futures.ProcessPoolExecutor和Future
ProcessPoolExecutor相关方法
submit() # 启动一个线程任务返回一个Future类的对象map() # 不相同任务不同参数启动多进程返回可迭代对象包含任务执行结果shutdown() # 停止进程
Future相关方法
result() # 任务执行结果exception() # 执行出现的异常
下载图片案例
from concurrent.futures import ProcessPoolExecutor
from urllib.request import urlopen, Request
import osheaders {User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/110.0.0.0 Safari/537.36,content-type: Content-Type: image/jpeg
}
def download_img(url: str):site_url Request(url, headersheaders)with urlopen(site_url) as web_file:img_data web_file.read()if not img_data:raise Exception(fError: can not load the image from {url})file_name os.path.basename(url)with open(file_name, wb) as f:f.write(img_data)return Download image successfully, {}.format(url)urls [https://img0.bdstatic.com/static/searchresult/img/baseimg3_4f26a23.png,# ...
]def main():with ProcessPoolExecutor() as ececutor:results ececutor.map(download_img, urls)for r in results:print(r)
if __name__ __main__:main()运行结果
PS F:\Code\python_code\high_python\python_advance\multiprocesses python .\multiprocess_pool.py
Download image successfully, https://img0.bdstatic.com/static/searchresult/img/baseimg3_4f26a23.png
