如您所知，在这种情况下使用锁会杀死多进程，因为您实际上会让所有进程都等待当前持有STDOUT的“权限”的进程释放互斥量。但是，从逻辑上讲，并行运行并与功能/子流程同步打印是排他的。
相反，您可以做的是让主流程充当子流程的“打印机”，这样子流程一旦完成/出现错误，然后然后才将要打印的内容发送回主流程。对于似乎不是“实时”的打印，您似乎是非常满意的（无论如何也不能如前所述），因此该方法应该恰好为您服务。所以：
import multiprocessing as mp
import random # just to add some randomness
from time import sleep
def foo(x):
output = ["[Process {}]: foo:".format(x)]
for i in range(5):
output.append('[Process {}] in foo {}'.format(x, i))
sleep(0.2 + 1 * random.random())
return "\n".join(output)
if __name__ == '__main__':
pool = mp.Pool(4)
for res in pool.imap_unordered(foo, range(4)):
print("[MAIN]: Process finished, response:")
print(res) # this will print as soon as one of the processes finishes/errors
pool.close()
这会给你（当然是YMMV）：
[MAIN]: Process finished, response:
[Process 2]: foo:
[Process 2] in foo 0
[Process 2] in foo 1
[Process 2] in foo 2
[Process 2] in foo 3
[Process 2] in foo 4
[MAIN]: Process finished, response:
[Process 0]: foo:
[Process 0] in foo 0
[Process 0] in foo 1
[Process 0] in foo 2
[Process 0] in foo 3
[Process 0] in foo 4
[MAIN]: Process finished, response:
[Process 1]: foo:
[Process 1] in foo 0
[Process 1] in foo 1
[Process 1] in foo 2
[Process 1] in foo 3
[Process 1] in foo 4
[MAIN]: Process finished, response:
[Process 3]: foo:
[Process 3] in foo 0
[Process 3] in foo 1
[Process 3] in foo 2
[Process 3] in foo 3
[Process 3] in foo 4
-如果您绝对必须使用其输出无法控制的功能，则可以包装子流程并捕获其STDOUT / STDERR，然后一旦完成（或引发异常），就可以将所有内容返回给流程’manager ‘打印到实际的STDOUT。通过这样的设置，我们可以foo()像：
def foo(x):
print("[Process {}]: foo:".format(x))
for i in range(5):
print('[Process {}] in foo {}'.format(x, i))
sleep(0.2 + 1 * random.random())
if random.random() < 0.0625: # let's add a 1/4 chance to err:
raise Exception("[Process {}] A random exception is random!".format(x))
return random.random() * 100 # just a random response, you can omit it
请注意，它非常高兴地不知道有什么东西试图破坏其操作模式。然后，我们将创建一个外部通用包装器（这样您就不必依赖于功能对其进行更改）实际上就 弄乱 了它的默认行为（不仅是这个函数，还有它在运行时可能调用的所有其他东西）：
def std_wrapper(args):
try:
from StringIO import StringIO # ... for Python 2.x compatibility
except ImportError:
from io import StringIO
import sys
sys.stdout, sys.stderr = StringIO(), StringIO() # replace stdout/err with our buffers
# args is a list packed as: [0] process function name; [1] args; [2] kwargs; lets unpack:
process_name = args[0]
process_args = args[1] if len(args) > 1 else []
process_kwargs = args[2] if len(args) > 2 else {}
# get our method from its name, assuming global namespace of the current module/script
process = globals()[process_name]
response = None # in case a call fails
try:
response = process(*process_args, **process_kwargs) # call our process function
except Exception as e: # too broad but good enough as an example
print(e)
# rewind our buffers:
sys.stdout.seek(0)
sys.stderr.seek(0)
# return everything packed as STDOUT, STDERR, PROCESS_RESPONSE | NONE
return sys.stdout.read(), sys.stderr.read(), response
现在，我们需要的是调用此包装器而不是所需的包装器foo()，并为其提供有关代表我们调用的信息：
if __name__ == '__main__':
pool = mp.Pool(4)
# since we're wrapping the process we're calling, we need to send to the wrapper packed
# data with instructions on what to call on our behalf.
# info on args packing available in the std_wrapper function above.
for out, err, res in pool.imap_unordered(std_wrapper, [("foo", [i]) for i in range(4)]):
print("[MAIN]: Process finished, response: {}, STDOUT:".format(res))
print(out.rstrip()) # remove the trailing space for niceness, print err if you want
pool.close()
因此，如果您现在运行它，将会得到以下内容：
[MAIN]: Process finished, response: None, STDOUT:
[Process 2]: foo:
[Process 2] in foo 0
[Process 2] in foo 1
[Process 2] A random exception is random!
[MAIN]: Process finished, response: 87.9658471743586, STDOUT:
[Process 1]: foo:
[Process 1] in foo 0
[Process 1] in foo 1
[Process 1] in foo 2
[Process 1] in foo 3
[Process 1] in foo 4
[MAIN]: Process finished, response: 38.929554421661194, STDOUT:
[Process 3]: foo:
[Process 3] in foo 0
[Process 3] in foo 1
[Process 3] in foo 2
[Process 3] in foo 3
[Process 3] in foo 4
[MAIN]: Process finished, response: None, STDOUT:
[Process 0]: foo:
[Process 0] in foo 0
[Process 0] in foo 1
[Process 0] in foo 2
[Process 0] in foo 3
[Process 0] in foo 4
[Process 0] A random exception is random!
尽管foo()只是打印掉或出错。当然，您可以使用此类包装器来调用任何函数，并将任何数量的args / kwargs传递给该函数。
但是，等一下！如果我们可以像这样包装我们的函数过程，并捕获它们的STDOUT / STDERR，我们肯定可以将其变成装饰器，并通过简单的装饰将其用于代码中。因此，对于我的最终建议：
import functools
import multiprocessing
import random # just to add some randomness
import time
def std_wrapper(func):
@functools.wraps(func) # we need this to unravel the target function name
def caller(*args, **kwargs): # and Now for the wrapper, nothing new here
try:
from StringIO import StringIO # ... for Python 2.x compatibility
except ImportError:
from io import StringIO
import sys
sys.stdout, sys.stderr = StringIO(), StringIO() # use our buffers instead
response = None # in case a call fails
try:
response = func(*args, **kwargs) # call our wrapped process function
except Exception as e: # too broad but good enough as an example
print(e) # NOTE: the exception is also printed to the captured STDOUT
# rewind our buffers:
sys.stdout.seek(0)
sys.stderr.seek(0)
# return everything packed as STDOUT, STDERR, PROCESS_RESPONSE | NONE
return sys.stdout.read(), sys.stderr.read(), response
return caller
@std_wrapper # decorate any function, it won't kNow you're siphoning its STDOUT/STDERR
def foo(x):
print("[Process {}]: foo:".format(x))
for i in range(5):
print('[Process {}] in foo {}'.format(x, i))
time.sleep(0.2 + 1 * random.random())
if random.random() < 0.0625: # let's add a 1/4 chance to err:
raise Exception("[Process {}] A random exception is random!".format(x))
return random.random() * 100 # just a random response, you can omit it
现在我们可以像以前一样调用包装函数了，而无需处理参数打包或任何类似的事情，因此我们回到了：
if __name__ == '__main__':
pool = multiprocessing.Pool(4)
for out, err, res in pool.imap_unordered(foo, range(4)):
print("[MAIN]: Process finished, response: {}, STDOUT:".format(res))
print(out.rstrip()) # remove the trailing space for niceness, print err if you want
pool.close()
输出与前面的示例相同，但包装更好，更易于管理。
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