下面是一个在python中支持非阻塞读和后台写的模块:

https://pypi.python.org/pypi/python-nonblock

提供一个函数，

nonblock_read将从流中读取数据，如果可用，否则返回一个空字符串(或None，如果流在另一端关闭，并且所有可能的数据都已读取)

你也可以考虑python-subprocess2模块，

https://pypi.python.org/pypi/python-subprocess2

这将添加到子流程模块。所以在subprocess返回的对象上。Popen”被添加了一个额外的方法，runInBackground。这将启动一个线程并返回一个对象，该对象将在写入stdout/stderr时自动填充，而不会阻塞主线程。

享受吧!

下面是我的代码，用于捕获子进程ASAP的每个输出，包括部分行。它同时泵浦，stdout和stderr的顺序几乎是正确的。

在Python 2.7 linux和windows上测试并正确工作。

#!/usr/bin/python
#
# Runner with stdout/stderr catcher
#
from sys import argv
from subprocess import Popen, PIPE
import os, io
from threading import Thread
import Queue
def __main__():
    if (len(argv) > 1) and (argv[-1] == "-sub-"):
        import time, sys
        print "Application runned!"
        time.sleep(2)
        print "Slept 2 second"
        time.sleep(1)
        print "Slept 1 additional second",
        time.sleep(2)
        sys.stderr.write("Stderr output after 5 seconds")
        print "Eol on stdin"
        sys.stderr.write("Eol on stderr\n")
        time.sleep(1)
        print "Wow, we have end of work!",
    else:
        os.environ["PYTHONUNBUFFERED"]="1"
        try:
            p = Popen( argv + ["-sub-"],
                       bufsize=0, # line-buffered
                       stdin=PIPE, stdout=PIPE, stderr=PIPE )
        except WindowsError, W:
            if W.winerror==193:
                p = Popen( argv + ["-sub-"],
                           shell=True, # Try to run via shell
                           bufsize=0, # line-buffered
                           stdin=PIPE, stdout=PIPE, stderr=PIPE )
            else:
                raise
        inp = Queue.Queue()
        sout = io.open(p.stdout.fileno(), 'rb', closefd=False)
        serr = io.open(p.stderr.fileno(), 'rb', closefd=False)
        def Pump(stream, category):
            queue = Queue.Queue()
            def rdr():
                while True:
                    buf = stream.read1(8192)
                    if len(buf)>0:
                        queue.put( buf )
                    else:
                        queue.put( None )
                        return
            def clct():
                active = True
                while active:
                    r = queue.get()
                    try:
                        while True:
                            r1 = queue.get(timeout=0.005)
                            if r1 is None:
                                active = False
                                break
                            else:
                                r += r1
                    except Queue.Empty:
                        pass
                    inp.put( (category, r) )
            for tgt in [rdr, clct]:
                th = Thread(target=tgt)
                th.setDaemon(True)
                th.start()
        Pump(sout, 'stdout')
        Pump(serr, 'stderr')

        while p.poll() is None:
            # App still working
            try:
                chan,line = inp.get(timeout = 1.0)
                if chan=='stdout':
                    print "STDOUT>>", line, "<?<"
                elif chan=='stderr':
                    print " ERROR==", line, "=?="
            except Queue.Empty:
                pass
        print "Finish"

if __name__ == '__main__':
    __main__()

I also faced the problem described by Jesse and solved it by using "select" as Bradley, Andy and others did but in a blocking mode to avoid a busy loop. It uses a dummy Pipe as a fake stdin. The select blocks and wait for either stdin or the pipe to be ready. When a key is pressed stdin unblocks the select and the key value can be retrieved with read(1). When a different thread writes to the pipe then the pipe unblocks the select and it can be taken as an indication that the need for stdin is over. Here is some reference code:

import sys
import os
from select import select

# -------------------------------------------------------------------------    
# Set the pipe (fake stdin) to simulate a final key stroke
# which will unblock the select statement
readEnd, writeEnd = os.pipe()
readFile = os.fdopen(readEnd)
writeFile = os.fdopen(writeEnd, "w")

# -------------------------------------------------------------------------
def getKey():

    # Wait for stdin or pipe (fake stdin) to be ready
    dr,dw,de = select([sys.__stdin__, readFile], [], [])

    # If stdin is the one ready then read it and return value
    if sys.__stdin__ in dr:
        return sys.__stdin__.read(1)   # For Windows use ----> getch() from module msvcrt

    # Must finish
    else:
        return None

# -------------------------------------------------------------------------
def breakStdinRead():
    writeFile.write(' ')
    writeFile.flush()

# -------------------------------------------------------------------------
# MAIN CODE

# Get key stroke
key = getKey()

# Keyboard input
if key:
    # ... do your stuff with the key value

# Faked keystroke
else:
    # ... use of stdin finished

# -------------------------------------------------------------------------
# OTHER THREAD CODE

breakStdinRead()

我添加这个问题是为了读一些子进程。Popen stdout。 下面是我的非阻塞读解决方案:

import fcntl

def non_block_read(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 ""

# Use example
from subprocess import *
sb = Popen("echo test && sleep 1000", shell=True, stdout=PIPE)
sb.kill()

# sb.stdout.read() # <-- This will block
non_block_read(sb.stdout)
'test\n'

现有的解决方案不适合我(详情见下文)。最后成功的是使用read(1)实现readline(基于这个答案)。后者不阻塞:

from subprocess import Popen, PIPE
from threading import Thread
def process_output(myprocess): #output-consuming thread
    nextline = None
    buf = ''
    while True:
        #--- extract line using read(1)
        out = myprocess.stdout.read(1)
        if out == '' and myprocess.poll() != None: break
        if out != '':
            buf += out
            if out == '\n':
                nextline = buf
                buf = ''
        if not nextline: continue
        line = nextline
        nextline = None

        #--- do whatever you want with line here
        print 'Line is:', line
    myprocess.stdout.close()

myprocess = Popen('myprogram.exe', stdout=PIPE) #output-producing process
p1 = Thread(target=process_output, args=(myprocess,)) #output-consuming thread
p1.daemon = True
p1.start()

#--- do whatever here and then kill process and thread if needed
if myprocess.poll() == None: #kill process; will automatically stop thread
    myprocess.kill()
    myprocess.wait()
if p1 and p1.is_alive(): #wait for thread to finish
    p1.join()

为什么现有的解决方案不起作用:

Solutions that require readline (including the Queue based ones) always block. It is difficult (impossible?) to kill the thread that executes readline. It only gets killed when the process that created it finishes, but not when the output-producing process is killed. Mixing low-level fcntl with high-level readline calls may not work properly as anonnn has pointed out. Using select.poll() is neat, but doesn't work on Windows according to python docs. Using third-party libraries seems overkill for this task and adds additional dependencies.

I have often had a similar problem; Python programs I write frequently need to have the ability to execute some primary functionality while simultaneously accepting user input from the command line (stdin). Simply putting the user input handling functionality in another thread doesn't solve the problem because readline() blocks and has no timeout. If the primary functionality is complete and there is no longer any need to wait for further user input I typically want my program to exit, but it can't because readline() is still blocking in the other thread waiting for a line. A solution I have found to this problem is to make stdin a non-blocking file using the fcntl module:

import fcntl
import os
import sys

# make stdin a non-blocking file
fd = sys.stdin.fileno()
fl = fcntl.fcntl(fd, fcntl.F_GETFL)
fcntl.fcntl(fd, fcntl.F_SETFL, fl | os.O_NONBLOCK)

# user input handling thread
while mainThreadIsRunning:
      try: input = sys.stdin.readline()
      except: continue
      handleInput(input)

在我看来，这比使用select或signal模块来解决这个问题要简洁一些，但它只适用于UNIX…