objectif

Consommer la sortie d’un processus au fil de l’eau sans bloquer.

code minimal

import subprocess, sys

code = "import time\nfor i in range(3):\n print(i)\n time.sleep(0.05)"
with subprocess.Popen([sys.executable, "-u", "-c", code], stdout=subprocess.PIPE, text=True) as p:
    lines = []
    for line in p.stdout:  # streaming
        lines.append(line.strip())
    p.wait()
print(lines)  # attendu: ['0', '1', '2']

utilisation

import subprocess, sys
p = subprocess.Popen([sys.executable, "-c", "print('hello')"], stdout=subprocess.PIPE, text=True)
out = p.communicate()[0].strip()
print(out == "hello")

variante(s) utile(s)

# lire stderr aussi
import subprocess, sys
p = subprocess.Popen([sys.executable, "-c", "import sys; sys.stderr.write('err\n')"], stderr=subprocess.PIPE, text=True)
err = p.communicate()[1].strip()
print(err == "err")

notes

• Utilisez -u (unbuffered) côté Python enfant pour des sorties immédiates.
• Évitez deadlocks: préférez communicate() si vous capturez stdout et stderr.