Asynchronous subprocess on Windows

Asynchronous subprocess on Windows

By : user3860727
Date : November 18 2020, 07:00 PM
wish helps you How bad is it to have to use threads? I encountered much the same problem and eventually decided to use threads to gather up all the data on a sub-process's stdout and stderr and put it onto a thread-safe queue which which the main thread can read in a blocking fashion, without having to worry about the threading going on behind the scenes.
It's not clear what trouble you anticipate with a solution based on threads and blocking. Are you worried about having to make the rest of your code thread-safe? That shouldn't be an issue since the IO thread wouldn't need to interact with any of the rest of your code or data. If you have very restrictive memory requirements or your pipeline is particularly long then perhaps you may feel unhappy about spawning so many threads. I don't know enough about your situation so I couldn't say if this is likely to be a problem, but it seems to me that since you're already spawning off extra processes a few threads to interact with them should not be a terrible burden. In my situation I have not found these IO threads to be particularly problematic.
code :

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asynchronous subprocess with Popen

asynchronous subprocess with Popen

By : Yan Solopov
Date : March 29 2020, 07:55 AM
help you fix your problem Using Windows 7 + python 2.6, I am trying to run a simulation model in parallel. I can launch multiple instances of the executable by double-clicking on them in my file browser. However, asynchronous calls with Popen result in each successive instance interrupting the previous one. For what it's worth, the executable returns text to the console, but I don't need to collect results interactively. , Enabled by @J.F. Sebastian's comment regarding the cwd argument.
code :
import multiprocessing, subprocess

def run(c):
    exe = os.path.join("<location>","folder",str(c),"program.exe")
    run = os.path.join("<location>","folder",str(c),"run.dat")
    subprocess.check_call([exe,run],cwd=os.path.join("<location>","folder"),creationflags = subprocess.CREATE_NEW_CONSOLE)

def main():
    pool = multiprocessing.Pool(3)
    for c in range(10):

if __name__ == '__main__':
Subprocess.call or Subprocess.Popen cannot use executables that are in PATH (Linux/Windows)

Subprocess.call or Subprocess.Popen cannot use executables that are in PATH (Linux/Windows)

By : zozaf
Date : March 29 2020, 07:55 AM
it fixes the issue I'm writing a programme that needs to run on both Linux and Windows and use executables (with parameters) that exist in the path. (Assumed) , Ok here is how I got it to work.
code :
env = os.environ
proc = subprocess.Popen(args, env=env)
asynchronous subprocess with timeout

asynchronous subprocess with timeout

By : Jo9
Date : March 29 2020, 07:55 AM
seems to work fine As mentioned previously, the call to process.communicate() is making your code wait for the completion of the subprocess. However, if you just remove the communicate() call, the thread will exit immediately after spawning the process, causing your thread.join() call to exit too soon, and you'll kill off the subprocess prematurely. To do what you want without polling or busy waiting, you can set a timer that will kill the process (and runner thread) after a timeout if the process has not yet finished:
code :
class Command(object):
  def __init__(self, cmd):
    self.cmd = cmd
    self.process = None

  def run(self, timeout):
    def target():
      print('Thread started')
      # May want/need to skip the shlex.split() when using shell=True
      # See Popen() constructor docs on 'shell' argument for more detail.
      args = shlex.split(self.cmd)
      self.process = subprocess.Popen(args, shell=True)

    def timer_callback():
        print('Terminating process (timed out)')

    thread = threading.Thread(target=target)
    self.timer = threading.Timer(timeout, timer_callback)
Communicate with subprocess without waiting for the subprocess to terminate on windows

Communicate with subprocess without waiting for the subprocess to terminate on windows

By : user6217778
Date : March 29 2020, 07:55 AM
I wish did fix the issue. I have a simple echoprocess.py: , The main problem is with the line...
code :
print proc.stdout.read()
print proc.stdout.readline()
data = sys.stdin.read()
data = sys.stdin.readline()
import sys

while True:
    data = sys.stdin.readline()
    sys.stdout.write("Here is the data: " + str(data))
from subprocess import Popen, PIPE

proc = Popen(["C:/python27/python.exe", "echoprocess.py"],
             stdin = PIPE,
             stdout = PIPE)

print proc.stdout.readline()
Running R script with subprocess on Windows, subprocess seems missing

Running R script with subprocess on Windows, subprocess seems missing

By : vamsi krishna
Date : March 29 2020, 07:55 AM
hope this fix your issue Check your python script and Rscript in are the same file location.
Example: Create a file named sb.R and subprocess_demo.py under Desktop location. Change directory to Desktop in command prompt and run following command python subprocess_demo.py
code :
c <- 3
print(paste("hello", c))
import subprocess
subprocess.call(['Rscript', "sb.R"])
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