Windows中具有多处理功能的Python日志记录 [英] Python Logging with Multiprocessing in Windows

问题描述

我有一个相当大的Python项目，该项目当前在Linux上运行，但我正在尝试扩展到Windows.我将代码简化为一个完整的示例，可以运行该示例来说明我的问题:我有两个类，Parent和Child.首先初始化父级，创建一个记录器，并生成一个子级进行工作:

I have a rather large Python project which currently runs on Linux but I am trying to expand to Windows. I've reduced the code to a full example which can be run to illustrate my problems: I have two classes, Parent and Child. Parent is initialized first, creates a logger, and spawns a Child to do work:

import logging
import logging.config
import multiprocessing

class Parent( object ):
    def __init__(self, logconfig):
        logging.config.dictConfig(logconfig)
        self.logger = logging.getLogger(__name__)

    def spawnChild(self):
        self.logger.info('One')
        c = Child(self.logger)
        c.start()

class Child(multiprocessing.Process):
    def __init__(self, logger):
        multiprocessing.Process.__init__(self)
        self.logger = logger

    def run(self):
        self.logger.info('Two')

if __name__ == '__main__':
    p = Parent({
            'version':1, 
            "handlers": {
                "console": {
                    "class": "logging.StreamHandler",
                    "stream": "ext://sys.stdout"
                },
            },
            "root": {
                "level": "DEBUG",
                "handlers": [
                    "console",
                    ]
                }
            }
        )
    p.spawnChild()

在linux(特别是ubuntu 12.04)上，我得到以下(预期)输出:

On linux (specifically, ubuntu 12.04), I get the following (expected) output:

user@ubuntu:~$ python test.py 
One
Two

但是，在Windows(特别是Windows 7)上，它会由于出现酸洗错误而失败:

But, on Windows (specifically, Windows 7), it fails with a pickling error:

C:\>python test.py
<snip>
pickle.PicklingError: Can't pickle <type 'thread.lock'>: it's not found as thread.lock

问题归结于Windows缺少真正的fork，因此在线程之间发送对象时必须对对象进行腌制.但是，记录器不能被腌制.我尝试使用__getstate__和__setstate__避免酸洗，并在Child中按名称引用:

The problem comes down to Windows' lack of a true fork, so objects have to be pickled when sent between threads. But, the logger can't be pickled. I've tried using __getstate__ and __setstate__ to avoid pickling, and reference by name in Child:

def __getstate__(self):
    d = self.__dict__.copy()
    if 'logger' in d.keys():
        d['logger'] = d['logger'].name
    return d

def __setstate__(self, d):
    if 'logger' in d.keys():
        d['logger'] = logging.getLogger(d['logger'])
    self.__dict__.update(d)

这与以前一样在Linux中有效，现在Windows不会因为PicklingError而失败.但是，我的输出仅来自父级:

This works in Linux just as before, and now Windows won't fail with the PicklingError. However, my output is only from Parent:

C:\>python test.py
One

C:\>

尽管没有消息抱怨找不到用于处理程序'__main__'的记录器"或任何其他错误消息，但孩子似乎无法使用记录器.我环顾四周，有一些方法可以完全重组我的程序登录方式，但这显然是不得已的方法.我希望我只是缺少一些明显的东西，而人群的智慧可以向我指出.

It seems that the child is unable to use the logger, despite no message complaining "No logger could be found for handler '__main__'" or any other error message. I've looked around and there are means by which I could completely restructure how I log in my program, but that's obviously a last resort. I'm hoping that I'm just missing something obvious, and that the wisdom of the crowd can point it out to me.

推荐答案

在大多数情况下，Logger对象是不可拾取的，因为它们在内部使用不可拾取的theading.Lock和/或file对象.您尝试的解决方法确实避免了腌制logger，但是最终在子进程中创建了一个完全不同的Logger，而该子进程恰好与父进程中的Logger具有相同的名称；您拨打的logging.config呼叫的效果会丢失.要获得所需的行为，您需要在子进程中重新创建记录器，然后调用logging.config.dictConfig:

In most cases, Logger objects are not picklable, because they use unpicklable theading.Lock and/or file objects internally. Your attempted workaround does avoid pickling the logger, but it ends up creating a completely different Logger in the child process, which happens to have the same name as the Logger in the parent; the effects of logging.config call you made are lost. To get the behavior you want you'll need to need to recreate the logger in the child process and re-call logging.config.dictConfig:

class Parent( object ):
    def __init__(self, logconfig):
        self.logconfig = logconfig
        logging.config.dictConfig(logconfig)
        self.logger = logging.getLogger(__name__)

    def spawnChild(self):
        self.logger.info('One')
        c = Child(self.logconfig)
        c.start()

class Child(multiprocessing.Process):
    def __init__(self, logconfig):
        multiprocessing.Process.__init__(self)
        self.logconfig = logconfig

    def run(self):
        # Recreate the logger in the child
        logging.config.dictConfig(self.logconfig)
        self.logger = logging.getLogger(__name__)

        self.logger.info('Two')

或者，如果您想继续使用__getstate__/__setstate__:

Or, if you want to keep using __getstate__/__setstate__:

class Parent( object ):
    def __init__(self, logconfig):
        logging.config.dictConfig(logconfig)
        self.logger = logging.getLogger(__name__)
        self.logconfig = logconfig

    def spawnChild(self):
        self.logger.info('One')
        c = Child(self.logger, self.logconfig)
        c.start()

class Child(multiprocessing.Process):
    def __init__(self, logger, logconfig):
        multiprocessing.Process.__init__(self)
        self.logger = logger
        self.logconfig = logconfig

    def run(self):
        self.logger.info('Two')

    def __getstate__(self):
        d = self.__dict__.copy()
        if 'logger' in d:
            d['logger'] = d['logger'].name
        return d

    def __setstate__(self, d):
        if 'logger' in d:
            logging.config.dictConfig(d['logconfig'])
            d['logger'] = logging.getLogger(d['logger'])
        self.__dict__.update(d)

这篇关于Windows中具有多处理功能的Python日志记录的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！