打印语句的日志记录模块：重复的日志条目

Question

更新：向下滚动至编辑部分（4），即可使用几乎完全可用的版本。还删除了EDIT SECTION（1），因为该帖子过长，否则可能是最没有帮助的部分。原来在编辑部分（1）中的链接在下面。

How do I duplicate sys.stdout to a log file in python?

这里是长时间的搜索者，但第一次提出问题。

EXPLANATION：

我需要使打印重定向到日志，因为我正在通过使用打印语句记录消息的系统调用来合并C代码。也有很多我的同事编写的旧Python代码被调用，它们也使用打印语句进行调试。

最终，我希望它能够为更新后的代码处理logging.info（'message'），而且还能够通过内置的日志记录模块重定向打印语句，以获取我无法更改或仅更改的代码还没有更新。

下面是我想出的一些示例代码，以简洁地演示我的问题。

问题：

1. 我将以下设置用于日志，但是每次打印时，日志中都会出现重复的条目（和空白行）。谁能解释为什么会这样？
2. 很高兴找出更好的日志记录设置，以便在通过日志记录重定向打印命令时，format语句包含正确的模块名称。
3. 我使用此Tee（object）类似乎偶尔会破坏事情。请参阅下面的支持信息部分。

我的代码：

编辑：最初是setuplog.Tee。init包含if os.path.exists(LOGNAME): os.remove(LOGNAME)。它已被删除并放入base.py。

setuplog.py：

#!/usr/bin/python
import sys
import os
import logging
import logging.config

LOGNAME = 'log.txt'

CONFIG = {
    'version': 1,
    'disable_existing_loggers': True,
    'formatters': {
        'simple': {
            'format': '%(module)s:%(thread)d: %(message)s'
            },
        },
    'handlers': {
        'console': {
            'level': 'NOTSET',
            'class': 'logging.StreamHandler',
            'formatter': 'simple'
            },
        'file': {
            'level': 'NOTSET',
            'class': 'logging.FileHandler',
            'formatter': 'simple',
            'filename': LOGNAME
            },
        },
    'root': {
        'level': 'NOTSET',
        'handlers': ['console', 'file']
        },
    }


class Tee(object):
    def __init__(self):
        logging.config.dictConfig(CONFIG)
        self.logger = logging.getLogger(__name__)
        self.stdout = sys.stdout
        sys.stdout = self
    def __del__(self):
        sys.stdout = self.stdout
    def write(self, data):
        self.logger.info(data)

base.py：

#!/usr/bin/python
import sys
import os
import logging
# My modules.
import setuplog
#import aux2


LOGNAME = 'log.txt'
if os.path.exists(LOGNAME):
    os.remove(LOGNAME)

not_sure_what_to_call_this = setuplog.Tee()

print '1 base'
logging.info('2 base')
print '3 base'
os.system('./aux1.py')
logging.info('4 base')
#aux2.aux2Function()
#logging.info('5 base')

aux1.py：

#!/usr/bin/python
import sys
import os
import logging
import setuplog

not_sure_what_to_call_this = setuplog.Tee()

def main():
    print '1 aux1'
    logging.info('2 aux1')
    print '3 aux1'
    logging.info('4 aux1')


if __name__ == '__main__':
    main()

aux2.py：

#!/usr/bin/python
import sys
import os
import logging
import setuplog

not_sure_what_to_call_this = setuplog.Tee()

def aux2Function():
    print '1 aux2'
    logging.info('2 aux2')
    print '3 aux2'

然后我从外壳程序“ ./base.py”运行并产生以下输出（在控制台和log.txt中：）]

setuplog:139833296844608: 1 aux1
setuplog:139833296844608:

aux1:139833296844608: 2 aux1
setuplog:139833296844608: 3 aux1
setuplog:139833296844608:

aux1:139833296844608: 4 aux1
如您所见，将重复打印生成的条目（问题1）。另外，我需要提出一个更好的约定来显示模块名称（问题2）。

支持问题3的信息

从base.py，如果我取消注释“ import aux2”，“ aux2.aux2Function（）”和“ logging.info（'5 base'）”，则这是新的输出（直接从控制台输入，因为这是仅将Python错误转到）：

base:140425995155264: 2 base
setuplog:140360687101760: 1 aux1
setuplog:140360687101760:

aux1:140360687101760: 2 aux1
setuplog:140360687101760: 3 aux1
setuplog:140360687101760:

aux1:140360687101760: 4 aux1
base:140425995155264: 4 base
aux2:140425995155264: 2 aux2
base:140425995155264: 5 base
Exception AttributeError: "'NoneType' object has no attribute 'stdout'" in <bound method Tee.__del__ of <setuplog.Tee object at 0x7fb772f58f10>> ignored
编辑部分（2）：

我一直在玩，并且有这种作品。这里是（再次）示例代码的更新版本。

之所以“有效”的原因是：

1. 我认为应该不惜一切代价避免出现例外，这要利用其中一个。
2. 日志输出现在有些手动。让我解释。 ％（name）s符合预期，但我必须手动设置。相反，我更喜欢某种描述符，它可以自动选择文件名，或者类似的名称（选择功能作为奖励？）。即使我希望报告的模块是打印语句的来源，而不是我的类将打印语句定向到日志记录模块的模块，％（module）的打印语句始终（正确）显示“ setuplog”。 >

setuplog.py：

#!/usr/bin/python
import sys
import os
import logging
import logging.config

def startLog(name):
    logname = 'log.txt'
    config = {
        'version': 1,
        'disable_existing_loggers': True,
        'formatters': {
            'simple': {
                'format': '%(name)s:%(module)s:%(thread)s: %(message)s'
                },
            },
        'handlers': {
            'console': {
                'level': 'NOTSET',
                'class': 'logging.StreamHandler',
                'formatter': 'simple'
                },
            'file': {
                'level': 'NOTSET',
                'class': 'logging.FileHandler',
                'formatter': 'simple',
                'filename': logname
                },
            },
        'root': {
            'level': 'NOTSET',
            'handlers': ['console', 'file'],
            },
        }
    logging.config.dictConfig(config)
    return logging.getLogger(name)

class Tee():
    def __init__(self, logger):
        self.stdout = sys.stdout
        self.data = ''
        self.logger = logger
        sys.stdout = self
    def __del__(self):
        try:
            sys.stdout = self.stdout
        except AttributeError:
            pass
    def write(self, data):
        self.data += data
        self.data = str(self.data)
        if '\x0a' in self.data or '\x0d' in self.data:
            self.data = self.data.rstrip('\x0a\x0d')
            self.logger.info(self.data)
            self.data = ''

base.py：

#!/usr/bin/python
import sys
import os
import logging
# My modules.
import setuplog
import aux2

LOGNAME = 'log.txt'
if os.path.exists(LOGNAME):
    os.remove(LOGNAME)
logger = setuplog.startLog('base')
setuplog.Tee(logger)

print '1 base'
logger.info('2 base')
print '3 base'
os.system('./aux1.py')
logger.info('4 base')
aux2.aux2Function()
logger.info('5 base')

aux1.py：

#!/usr/bin/python
import sys
import os
import logging
import setuplog


def main():
    logger = setuplog.startLog('aux1')
    setuplog.Tee(logger)
    print '1 aux1'
    logger.info('2 aux1')
    print '3 aux1'
    logger.info('4 aux1')


if __name__ == '__main__':
    main()

aux2.py：

#!/usr/bin/python
import sys
import os
import logging
import setuplog


def aux2Function():
    logger = setuplog.startLog('aux2')
    setuplog.Tee(logger)
    print '1 aux2'
    logger.info('2 aux2')
    print '3 aux2'

和输出：

base:setuplog:139712687740736: 1 base
base:base:139712687740736: 2 base
base:setuplog:139712687740736: 3 base
aux1:setuplog:140408798721856: 1 aux1
aux1:aux1:140408798721856: 2 aux1
aux1:setuplog:140408798721856: 3 aux1
aux1:aux1:140408798721856: 4 aux1
base:base:139712687740736: 4 base
aux2:setuplog:139712687740736: 1 aux2
aux2:aux2:139712687740736: 2 aux2
aux2:setuplog:139712687740736: 3 aux2

编辑部分（3）：

感谢对reddit（http://www.reddit.com/r/learnpython/comments/1kaduo/python_logging_module_for_print_statements/cbn2lef）的精彩答复，我能够针对AttributeError进行开发。我没有使用异常，而是将类转换为单例。

这里是更新的Tee类的代码：

class Tee(object):
    _instance = None
    def __init__(self, logger):
        self.stdout = sys.stdout
        self.data = ''
        self.logger = logger
        sys.stdout = self
    def __new__(cls, *args, **kwargs):
        if not cls._instance:
            cls._instance = super(Tee, cls).__new__(cls, *args, **kwargs)
        return cls._instance
    def __del__(self):
        sys.stdout = self.stdout
    def write(self, data):
        self.data += data
        self.data = str(self.data)
        if '\x0a' in self.data or '\x0d' in self.data:
            self.data = self.data.rstrip('\x0a\x0d')
            self.logger.info(self.data)
            self.data = ''
编辑部分（4）：
这几乎完全有效！它足以让我实现它。现在唯一的问题是使输出格式更有用。例如，对于所有重新路由的打印语句，％（filename）s是setuplog.py。如果％（filename）s是源自print语句的文件，那将更加有益。有什么想法吗？

而且，我不得不放弃字典方法。我可以完成所有工作的唯一方法是通过Python代码设置记录器。

最后一点，查看aux3.py。如果使用os.system而不是子进程，则日志记录的顺序会混乱。有谁知道解决方法仍然可以使用os.system并获得正确的顺序（因此我不必将每个最后的os.system都更改为subprocess.Popen）？

setuplog.py（您可以忽略功能startDictLog和startFileLog，因为它们不起作用。但是，startCodeLog可以！）：]]

#!/usr/bin/python
import sys
import os
import logging
import logging.config

def startLog(name, propagate):
    '''The only point of this function was to enable me to quickly
    and easily switch how I wanted to configure the logging. So far,
    I have only been able to get the last way working
    (startCodeLog).'''
    #return startDictLog(name)
    #return startFileLog(name)
    return startCodeLog(name, propagate)

def startDictLog(name):
    '''Configure logging usinga dictionary.'''
    LOGNAME = 'loop.log'
    DEBUGNAME = 'debug.log'
    config = {
        'version': 1,
        'disable_existing_loggers': True,
        'formatters': {
            'bare': {
                # Added the BARE to distinguish between normal prints
                # and those that get rerouted. In use, I would format it
                # such that only the message is printed.
                'format': 'BARE: %(message)s'
                },
            'simple': {
                'format': '%(module)s-%(name)s: %(message)s'
                },
            'time': {
                'format': '%(asctime)s-%(filename)s-%(module)s-%(name)s: %(message)s',
                'datefmt': '%H:%M:%S'
                },
            },
        'handlers': {
            'console': {
                'level': 'NOTSET',
                'class': 'logging.StreamHandler',
                'formatter': 'bare'
                },
            'normal': {
                'level': 'INFO',
                'class': 'logging.FileHandler',
                'formatter': 'simple',
                'filename': LOGNAME
                },
            'debug': {
                'level': 'NOTSET',
                'class': 'logging.FileHandler',
                'formatter': 'time',
                'filename': DEBUGNAME
                },
            },
        'root': {
            'level': 'NOTSET',
            'handlers': ['console', 'normal', 'debug'],
            },
        }
    logging.config.dictConfig(config)
    return logging.getLogger(name)

def startFileLog(name):
    '''Configure logging using a configuration file.'''
    CONFIGFILE = 'logging.conf'
    logging.config.fileConfig(CONFIGFILE)
    return logging.getLogger(name)

def startCodeLog(name, propagate):
    '''Configure logging using this code.'''
    LOGFILE = 'loop.log'
    DEBUGFILE = 'debug.log'
    _logger = logging.getLogger(name)
    _logger.setLevel(logging.NOTSET)
    if propagate in [False, 'n', 'no', 0]:
        _logger.propagate = False
    _console = logging.StreamHandler()
    _normal = logging.FileHandler(LOGFILE)
    _debug = logging.FileHandler(DEBUGFILE)

    _bare = logging.Formatter('BARE: %(message)s')
    _simple = logging.Formatter('%(module)s-%(name)s: %(message)s')
    _time = logging.Formatter('%(asctime)s-%(module)s-%(name)s: %(message)s',
                                       datefmt = '%H:%M:%S')
    # I added _complex only here, to the working way of setting up the configuration,
    # in hopes that this data may help someone figure out how to get the printout
    # to be more useful. For example, it's not helpful that the filename is
    # setuplog.py for every print statement. It would be more beneficial to somehow
    # get the filename of where the print statement originated.
    _complex = logging.Formatter('%(filename)s-%(funcName)s-%(name)s: %(message)s')

    # Normally this is set to _bare to imitate the output of the old version of the
    # scripts I am updating, but for our purposes, _complex is more convenient.
    _console.setLevel(logging.NOTSET)
    _console.setFormatter(_complex)

    # This imitates the format of the logs from versions before I applied this update.
    _normal.setLevel(logging.INFO)
    _normal.setFormatter(_bare)

    # This is a new log file I created to help me debug other aspects of the scipts
    # I am updating.
    _debug.setLevel(logging.DEBUG)
    _debug.setFormatter(_time)

    _logger.addHandler(_console)
    _logger.addHandler(_normal)
    _logger.addHandler(_debug)
    return _logger

class Tee(object):
    '''Creates a singleton class that tees print statements to the
    handlers above.'''
    _instance = None
    def __init__(self, logger):
        self.stdout = sys.stdout
        self.logger = logger
        sys.stdout = self
        self._buf = ''
        # Part of old method in the write function.
        #self.data = ''
    def __new__(cls, *args, **kwargs):
        '''This is the singleton implementation. This avoids errors with
        multiple instances trying to access the same standard output.'''
        if not cls._instance:
            cls._instance = super(Tee, cls).__new__(cls, *args, **kwargs)
        return cls._instance
    def write(self, data):
        # This method doesn't work with how I had to implement subprocess.
        #self.data = data.rstrip('\r\n')
        #if self.data:
        #    self.logger.info(self.data)

        # Also doesn't seem to work with my subprocess implementation.
        #self.data += data
        #self.data = str(self.data)
        #if '\x0a' in self.data or '\x0d' in self.data:
        #    self.data = self.data.rstrip('\x0a\x0d')
        #    self.logger.info(self.data)
        #    self.data = ''

        # Only way I could get it working with my subprocess implementation.
        self._buf = ''.join([self._buf, data])
        while '\n' in self._buf:
            line, _, tail = self._buf.partition('\n')
            if line.strip():
                self.logger.info(line)
            self._buf = tail
base.py：
#!/usr/bin/python
import sys
import os
import logging
import subprocess
# My modules below.
import setuplog
import aux2

# It is assumed that this script will be executed via the command line,
# and each time we run it, we want new log files.
LOGNAME = 'loop.log'
DEBUGNAME ='debug.log'
if os.path.exists(LOGNAME):
    os.remove(LOGNAME)
if os.path.exists(DEBUGNAME):
    os.remove(DEBUGNAME)

# It seems more convenient to store the logging configuration elsewhere,
# hence my module setuplog.
logger = setuplog.startLog('', True)
logger = setuplog.startLog('base', False)
# This initializes sys.stdout being redirected through logging. Can anyone
# explain how calling this class achieves this? I am a bit fuzzy on my
# understanding here.
setuplog.Tee(logger)

# Test to see how it works in this module.
print '1 base'
logger.info('2 base')
print '3 base'

# Below shows how to get logging to work with scripts that can
# not be modified. In my case, I have C code that I don't want to modify,
# but I still need to log it's output.

# I will have to go through the old code and change all os.system calls
# to instead utilize subprocess. Too bad because this will take some time
# and be "busy work", but at least it works. What can ya do, os.system is
# depreciated anyway. The positive side is that only the root application
# needs to change its system calls to use subprocess. The scipts that it
# calls upon can remain untouched.

aux1_py_path = '"%s"' % os.path.join(os.path.dirname(__file__), 'aux1.py')
#os.system(aux1_py_path) # Example to show how os.system doesn't work.
print 'aux1_py_path:', aux1_py_path
sys_call = subprocess.Popen(aux1_py_path, shell=True, stdout=subprocess.PIPE,
                            stderr=subprocess.PIPE)
sys_stdout, sys_stderr = sys_call.communicate()
print sys_stdout
print sys_stderr

# This is to ensure that the order of the logging events is correct. With an
# old method I used (not with logging, simply redirecting stdout into an
# opened file), the order would often get messed up.
logger.info('4 base')
# This example is to show how to get logging to work with Python scripts I am
# willing to modify, at least partially. See aux2.py. It is simply a print
# statement, followed by a logging statement, followed by another print
# statement. They all output properly with this method.
aux2.aux2Function()
# Again to ensure the order of events is correct.
logger.info('5 base')
aux1.py：
#!/usr/bin/python
import logging
import subprocess
import os

def main():
    '''We expect the print statements to go through, as they are
    being sent to logging. However, these logging statements
    do nothing as no logger has been instantiated. This is the
    behavior we should expect, as this script mimics a script
    that we would not modify, so it would not have logging calls
    anyway.'''
    print '1 aux1'
    logging.info('2 aux1')
    print '3 aux1'
    logging.info('4 aux1')

    # Here, neither option works unless the root of all these calls
    # was made with subprocess and in the script that called the
    # tee class. If both conditions are met, subprocess works as it
    # should. However, os.system returns the print out from the call
    # out of order.

    aux3_py_path = '"%s"' % os.path.join(os.path.dirname(__file__), 'aux3.py')
    #os.system(aux3_py_path)
    sys_call = subprocess.Popen(aux3_py_path, shell=True,
                                stdout=subprocess.PIPE,
                                stderr=subprocess.PIPE)
    sys_stdout, sys_stderr = sys_call.communicate()
    print sys_stdout
    print sys_stderr

if __name__ == '__main__':
    main()
aux2.py：
#!/usr/bin/python
import sys
import os
import logging
import setuplog

def aux2Function():
    # The following two lines are not necessary for most functionality.
    # However, if the following two lines are uncommented, then %(name)s
    # in the format descriptor of logging will correctly be 'aux2' rather
    # than base. Both lines are required for this to work.
    logger = setuplog.startLog('aux2', False)
    setuplog.Tee(logger)

    print '1 aux2'
    logging.info('2 aux2')
    print '3 aux2'
aux3.py：
#!/usr/bin/python
import logging

def main():
    '''See __doc__ for aux1.py. Again, we don't expect the logging.info
    to work, but that's okay because theoretically, this is some script
    we can't modify that simply generates output with print or print
    like functions.'''
    print '1 aux3'
    logging.info('2 aux3')
    print '3 aux3'

if __name__ == '__main__':
    main()
logging.conf（无效）：
[loggers]
keys=root

[handlers]
keys=console,normal,debug

[formatters]
keys=bare,simple,time

[logger_root]
level=NOTSET
handlers=console,normal,debug

[handler_console]
level=NOTSET
class=StreamHandler
formatter=bare
args=(sys.stdout,)

[handler_normal]
level=INFO
class=FileHandler
formatter=simple
args=('loop.log',)

[handler_debug]
level=DEBUG
class=FileHandler
formatter=time
args=('debug.log',)

[formatter_bare]
format=%(message)s

[formatter_simple]
format=%(module)s-%(name)s: %(message)s

[formatter_time]
format=%(asctime)s-%(filename)s-%(module)s-%(name)s: %(message)s
datefmt=%H:%M:%S
更新：向下滚动至编辑部分（4），即可使用几乎完全可用的版本。还删除了EDIT SECTION（1），因为该帖子过长，否则可能是最没有帮助的部分。 ...

这里至少是您第一个问题的部分答案。您会在每个print上获得这些空行，因为Python 2.x中的print语句可能会调用stdout.write() twice

，一次与评估语句中表达式的数据有关，然后与可选的换行符没有被逗号引起的抑制。

此外，如果将INFO级消息发送到设置为level为'NOTSET'的记录器，则默认情况下，根据记录器文档，消息也会在sys.stderr上回显，这就是为什么即使Tee有效，也可以查看控制台输出。我看不到重复的日志条目。

为了防止出现空白行，请尝试使用此Tee类定义。请注意write()方法的修改（已更新为单例以匹配您的“编辑部分（3）”）：

class Tee(object):
    _instance = None
    def __init__(self, logger):
        self.stdout = sys.stdout
        self.logger = logger
        sys.stdout = self
    def __new__(cls, *args, **kwargs):
        if not cls._instance:
            cls._instance = super(Tee, cls).__new__(cls, *args, **kwargs)
        return cls._instance
    def __del__(self):
        sys.stdout = self.stdout
    def write(self, data):
        data = data.rstrip('\r\n')
        if data: # anything left?
           self.logger.info(data)
有了此更新以及您所有其他的更新，对于我来说似乎很有效（包括未注释的aux2内容。从您的角度来看是否还有其他问题？如果是这样，那么您最初的长期问题就变得更加如此了。并且应该彻底清除，只保留最新的代码，并专注于所有剩余的问题。

Answer 1

这里至少是您第一个问题的部分答案。您会在每个print上获得这些空行，因为Python 2.x中的print语句可能会调用stdout.write() twice