[SOLVED] Workaround for timeout failure on subprocess.run?

Issue

Is there a workaround for https://bugs.python.org/issue37424 ?

That bug is biting me. I'm on Raspberry Pi OS which got Python 3.7.3 when I installed with sudo apt install python3.

Unfortunately that bug is fixed only in Python 3.7.5 and later.

• Is there a workaround on Python 3.7.3?
• If not, can someone point me at a detailed explanation of how to (I suppose, compile and) install Python 3.7.5 (or later) on Raspberry Pi OS? I've been told it's "complicated" and may break other things (see https://www.raspberrypi.org/forums/viewtopic.php?t=291158 )

I just need the timeout to work.

FWIW, here's my code:

def command(string, verbose=None, echo_commands=ECHO_COMMANDS, timeout=SHORT_TIMEOUT):
    ''' Executes string as a command by the OS.
        Returns subprocess.CompletedProcess (stout, stderr, returncode, etc.).

        Note usual security precautions since shell=True (DO NOT use this with user input).
    '''

    if verbose is None:
        verbose = VERBOSE

    while True:
        try:
            if echo_commands:
                print("command:", string)

            cp = subprocess.run(string, shell=True, capture_output=True, text=True, timeout=timeout)

            if verbose:
                print(cp.stderr, cp.stdout)

            return cp

        except Exception as e:
            print(e)
            reboot_camera() #...and try again

Solution

I found a solution - use shell=False (then timeouts work) and use shlex.split to parse the command into parameters in Python instead of asking the shell to do it. So:

string = shlex.split(string) # workaround for https://bugs.python.org/issue37424 (plus shell=False instead of True)

cp = subprocess.run(string, shell=False, capture_output=True, text=True, timeout=timeout)

In order to make it work also on Windows, I had to modify the string that contains the name of the executable to include the full path (seems like Windows doesn't search $PATH without shell==True).

Old: CHDKPTP_EXE = r'chdkptp'

New: CHDKPTP_EXE = r'c:\\bin\\chdkptp.bat'

Answered By - nerdfever.com