非阻塞 subprocess.call

2022-01-18 00:00:00 python subprocess

问题描述

我正在尝试进行非阻塞子进程调用以从我的 main.py 程序运行 slave.py 脚本.我需要将 args 从 main.py 传递给 slave.py 一次，当它(slave.py)第一次通过 subprocess.call 启动时，这个 slave.py 运行一段时间然后退出.

I'm trying to make a non blocking subprocess call to run a slave.py script from my main.py program. I need to pass args from main.py to slave.py once when it(slave.py) is first started via subprocess.call after this slave.py runs for a period of time then exits. 

main.py
for insert, (list) in enumerate(list, start =1):

    sys.args = [list]
    subprocess.call(["python", "slave.py", sys.args], shell = True)


{loop through program and do more stuff..}

还有我的奴隶脚本

slave.py
print sys.args
while True:
    {do stuff with args in loop till finished}
    time.sleep(30)

目前，slave.py 阻止 main.py 运行其其余任务，我只是希望 slave.py 独立于 main.py，一旦我将 args 传递给它.这两个脚本不再需要通信.

Currently, slave.py blocks main.py from running the rest of its tasks, I simply want slave.py to be independent of main.py, once I've passed args to it. The two scripts no longer need to communicate.

我在网上找到了一些关于非阻塞 subprocess.call 的帖子，但其中大部分都集中在需要与 slave.py 进行通信的某个点上，而我目前不需要.有谁知道如何以简单的方式实现这个......?

I've found a few posts on the net about non blocking subprocess.call but most of them are centered on requiring communication with slave.py at some-point which I currently do not need. Would anyone know how to implement this in a simple fashion...?

解决方案

你应该使用 subprocess.Popen 而不是 subprocess.call.

You should use subprocess.Popen instead of subprocess.call.

类似:

subprocess.Popen(["python", "slave.py"] + sys.argv[1:])

来自 关于 subprocess.call 的文档:

From the docs on subprocess.call:

运行 args 描述的命令.等待命令完成，然后返回 returncode 属性.

Run the command described by args. Wait for command to complete, then return the returncode attribute.

(如果您要使用 shell = True，也不要使用列表来传递参数).

(Also don't use a list to pass in the arguments if you're going to use shell = True).

这是一个演示非阻塞 suprocess 调用的 MCVE1 示例:

Here's a MCVE1 example that demonstrates a non-blocking suprocess call:

import subprocess
import time

p = subprocess.Popen(['sleep', '5'])

while p.poll() is None:
    print('Still sleeping')
    time.sleep(1)

print('Not sleeping any longer.  Exited with returncode %d' % p.returncode)

另一种依赖于对 python 语言的最新更改以允许基于协同例程的并行性的替代方法是:

An alternative approach that relies on more recent changes to the python language to allow for co-routine based parallelism is:

# python3.5 required but could be modified to work with python3.4.
import asyncio

async def do_subprocess():
    print('Subprocess sleeping')
    proc = await asyncio.create_subprocess_exec('sleep', '5')
    returncode = await proc.wait()
    print('Subprocess done sleeping.  Return code = %d' % returncode)

async def sleep_report(number):
    for i in range(number + 1):
        print('Slept for %d seconds' % i)
        await asyncio.sleep(1)

loop = asyncio.get_event_loop()

tasks = [
    asyncio.ensure_future(do_subprocess()),
    asyncio.ensure_future(sleep_report(5)),
]

loop.run_until_complete(asyncio.gather(*tasks))
loop.close()

1使用 python2.7 & 在 OS-X 上测试python3.6

1Tested on OS-X using python2.7 & python3.6

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