在终端中导入Python库

Question

I need to run a Python script in a terminal, several times. This script requires me to import some libraries. So every time I call the script in the terminal, the libraries are loaded again, which results in a loss of time. Is there any way I can import the libraries once and for all at the beginning? (If I try the "naive" way, calling first a script just to import libraries then running my code, it doesn't work).

EDIT: I need to run the script in a terminal because actually it is made to serve in another program developed in Java. The Java code calls the Pythin script in the terminal, reads its result and processes it, then calls it again.

Answer 1

The libraries will be unloaded once the script finishes, so the best way you can handle this is to write the script so it can iterate however many times you want, rather than running the whole script multiple times. I would likely use input() (or raw_input() if you're running Python2) to read in however many times you want to iterate over it, or use a library like click to create a command line argument for it.

Answer 2

One solution is that you can leave the python script always running and use a pipe to communicate between processes like the code below taken from this answer.

import os, time

pipe_path = "/tmp/mypipe"
if not os.path.exists(pipe_path):
    os.mkfifo(pipe_path)
# Open the fifo. We need to open in non-blocking mode or it will stalls until
# someone opens it for writting
pipe_fd = os.open(pipe_path, os.O_RDONLY | os.O_NONBLOCK)
with os.fdopen(pipe_fd) as pipe:
    while True:
        message = pipe.read()
        if message:
            print("Received: '%s'" % message)
        print("Doing other stuff")
        time.sleep(0.5)