从正在运行的程序中获取变量 [英] Get a variable from a running program

问题描述

我有一个运行了几天的脚本，并且在其中有一个计数器.计数器会定期写入文件，是否可以从其他python脚本，linux命令甚至Java中找出计数器设置的值?

I have a script that runs for days, and inside it there's a counter. The counter gets written to a file periodically, is it possible to find out the value that the counter is set from either another python script, linux command, or even java?

简单的python计数器示例:

Example of simple python counter:

import time
import random

a = 0
while True:
    a +=1
    time.sleep(random.random())

我对给定时间的 a 的值感兴趣.

I'm interested in the value of a at a given time.

推荐答案

是的，您可以使用任何IPC方法，例如，您可以将计数器发送到套接字:

Yes, you could use any IPC method e.g., you could send the counter over a socket:

self.request.sendall(json.dumps(dict(counter=a)).encode('ascii'))

---

如果要从无法修改的已经运行的进程中获取值，则可以尝试附加调试器:

$ sudo gdb python <pid of running process>

要启用特定于python的帮助程序命令，请添加到您的〜/.gdbinit :

To enable python-specific helper commands, add to your ~/.gdbinit:

add-auto-load-safe-path /path/to/python-gdb.py

示例gdb会话可能类似于:

The example gdb session could look like:

>>> thread apply all py-list

Thread 1 (Thread 0x7f68ff397700 (LWP 9807)):
   2    import random
   3    
   4    a = 0
   5    while True:
   6        a +=1
  >7        time.sleep(random.random())
>>> py-print a
global 'a' = 83

通过另一个Python脚本，您可以以批处理模式运行gdb:

From another Python script, you could run gdb in the batch mode:

#!/usr/bin/env python
import shlex
import subprocess

cmd = shlex.split("sudo gdb --batch -ex 'py-print a' python") + [str(pid)]
output = subprocess.check_output(cmd, stderr=subprocess.DEVNULL,
                                 cwd=path_to_python_gdb)
a = int(output.rsplit(b'\n', 2)[-2].rpartition(b' ')[2])

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