So I have a python script that runs a loop in which it calls a program A through subprocess.Popen waits for its output, then saves the output and then calls it again and so on. (This keeps happening for a number of runs I set as an input)

The thing is that I have a timer so that whenever the program A takes more than a particular threshold_time, the script kills the process with process.kill() and moves on to the next iteration.

The problem is that even though everything seems to work fine even for 300 runs, sometimes I get this error: 

    File "C:\Python27\lib\subprocess.py", line 1002, in terminate
    _subprocess.TerminateProcess(self._handle, 1)
    WindowsError: [Error 5] Access is denied

and then the script dies.

The referred script part:

timeout = TIME_CONST
for run in runs:
    killed = False
    start = time.clock()
    p = subprocess.Popen("SOME.CMD", cwd=r"some_dir") 
    # Monitor process. If it hits threshold, kill it and go to the next run
    while p.poll() is None:
        time.sleep(20) 
        secs_passed = time.clock() - start

        ### the following was my initial buggy line ###
        #if secs_passed >= timeout: 

        ### corrected line after jedislight's answer ###
        #if the time is over the threshold and process is still running, kill it
        if secs_passed >= timeout and p.poll is None: 
            p.kill()
            killed = True  
            break
    if killed: continue

Do you have any suggestions what the problem might be?

EDIT: Accepted answer and fixed the code. Thanks @jedislight for your feedback!

python subprocess popen
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