python - 如何清除 Python 子进程中的标准输出？

Question

此代码段将在 Windows 中 ping 一个 ip 地址并每 2 秒获取一次输出行，但是，我发现运行后 ping.exe 进程的内存增加非常缓慢，如果我将它部署到 ping 1000 ip parallel，很快它会导致服务器挂起，我想这可能是因为标准输出缓冲区，我可以知道如何清除标准输出或限制其大小吗？谢谢!

...
proc = subprocess.Popen(['c:\windows\system32\ping.exe','127.0.0.1', '-l', '10000', '-t'],stdout=subprocess.PIPE, creationflags=subprocess.CREATE_NEW_PROCESS_GROUP) 

while True: 
    time.sleep(2)
    os.kill(proc.pid, signal.CTRL_BREAK_EVENT) 
    line = proc.stdout.readline() 

Answer 1

由于读取之间有 2 秒的超时，ping 生成的行数比您正在读取的行数多得多。我会将 os.kill 调用移至另一个线程，并使用主线程从 proc.stdout 中读取每一行:

import sys, os
import subprocess
import threading
import signal
import time

#Use ctrl-c and ctrl-break to terminate the script/ping

def sigbreak(signum, frame):
    import sys
    if proc.poll() is None:
        print('Killing ping...')
        proc.kill()
    sys.exit(0)

signal.signal(signal.SIGBREAK, sigbreak)
signal.signal(signal.SIGINT, sigbreak)

#executes in a separate thread
def run(pid):
    while True:
        time.sleep(2)
        try: 
            os.kill(pid, signal.CTRL_BREAK_EVENT)
        except WindowsError:
            #quit the thread if ping is dead 
            break

cmd = [r'c:\windows\system32\ping.exe', '127.0.0.1', '-l', '10000', '-t']
flags = subprocess.CREATE_NEW_PROCESS_GROUP
proc = subprocess.Popen(cmd, stdout=subprocess.PIPE, creationflags=flags)
threading.Thread(target=run, args=(proc.pid,)).start()

while True:
    line = proc.stdout.readline()
    if b'statistics' in line:
        #I don't know what you're doing with the ping stats.
        #I'll just print them.
        for n in range(4):
            encoding = getattr(sys.stdout, 'encoding', 'ascii') 
            print(line.decode(encoding).rstrip())
            line = proc.stdout.readline()
        print()