python popen.stdout.readline() 掛起

Question

我遇到了一個問題...有誰知道為什么這段代碼掛在 while 循環中。 循環似乎沒有捕捉到stdout的最后一行。

working_file = subprocess.Popen(["/pyRoot/iAmACrashyProgram"], stdout=subprocess.PIPE, stdin=subprocess.PIPE, stderr=subprocess.PIPE)

line = working_file.stdout.readline()
working_file.stdout.flush()
while working_file != "" :
    print(line)
    line = working_file.stdout.readline()
    working_file.stdout.flush()

當遇到readline()時，腳本會掛起，光標只會閃爍。 我不明白為什么。 任何人都可以透露一些信息嗎？

Answer 1

進行非阻塞讀取對您有幫助嗎？

import fcntl
import os

def nonBlockReadline(output):
    fd = output.fileno()
    fl = fcntl.fcntl(fd, fcntl.F_GETFL)
    fcntl.fcntl(fd, fcntl.F_SETFL, fl | os.O_NONBLOCK)
    try:
        return output.readline()
    except:
        return ''

working_file = subprocess.Popen(["/pyRoot/iAmACrashyProgram"], stdout=subprocess.PIPE, stdin=subprocess.PIPE, stderr=subprocess.PIPE)

line = nonBlockReadline(working_file.stdout)
working_file.stdout.flush()
while working_file != "" :
    print(line)
    line = nonBlockReadline(working_file.stdout)
    working_file.stdout.flush()

我不確定你到底想做什么，但這會更好嗎？ 它只是讀取所有數據，而不是一次只讀取一行。 它對我來說更具可讀性。

import fcntl
import os

def nonBlockRead(output):
    fd = output.fileno()
    fl = fcntl.fcntl(fd, fcntl.F_GETFL)
    fcntl.fcntl(fd, fcntl.F_SETFL, fl | os.O_NONBLOCK)
    try:
        return output.read()
    except:
        return ''

working_file = subprocess.Popen(["/pyRoot/iAmACrashyProgram"], stdout=subprocess.PIPE, stdin=subprocess.PIPE, stderr=subprocess.PIPE)

stdout = ''

while working_file.poll() is None:
    stdout += nonBlockRead(working_file.stdout)

# we can probably save some time and just print it instead...
#print(stdout)

stdout = stdout.splitlines()
for line in stdout:
    print(line)

編輯：應該更適合您的用例的通用腳本：

import fcntl
import os

def nonBlockRead(output):
    fd = output.fileno()
    fl = fcntl.fcntl(fd, fcntl.F_GETFL)
    fcntl.fcntl(fd, fcntl.F_SETFL, fl | os.O_NONBLOCK)
    try:
        return output.read()
    except:
        return ''

working_file = subprocess.Popen(["/pyRoot/iAmACrashyProgram"], stdout=subprocess.PIPE, stdin=subprocess.PIPE, stderr=subprocess.PIPE)

while working_file.poll() is None:
    stdout = nonBlockRead(working_file.stdout)

    # make sure it returned data
    if stdout:
        # process data
        working_file.stdin.write(something)