调用子流程后，Python脚本未继续

Question

I have a python script calling a java file with the subprocess module:

import subprocess
java_cmd = ['java', '-cp', 'bin/stuff/:lib/asm-all-3.3.jar:lib/jdom.jar',
      'ch.idsia.scenarios.Main']
subprocess.call(java_cmd, shell=False)
print "Hello world"

This works correctly, and the java file then waits for the python script to continue and connect a socket, as I want it to. But the python script doesn't continue. Why not? I know it doesn't because the print statement never executes.

Everything runs as expected when I manually run the java file from Eclipse and then execute the python script from the command line. I also tried with subprocess.Popen() instead of subprocess.call() , with no difference in the outcome.

Answer 1

Thank you @KSFT; subprocess.call() doesn't return until the command finishes, but subprocess.Popen() does. So I made the call with subprocess.Popen() and then time.sleep(0.5) . Having the python script wait 0.5 seconds allows the java file enough time to open and initialize the socket connections.

Answer 2

subprocess.call() doesn't return until the command it runs finishes. You can use multithreading to run something else at the same time.