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python日志記錄模塊實(shí)例及改進(jìn)

更新時(shí)間：2017年02月12日 14:18:05 作者：sxhlinux

許多應(yīng)用程序中都會(huì)有日志模塊，用于記錄系統(tǒng)在運(yùn)行過(guò)程中的一些關(guān)鍵信息，以便于對(duì)系統(tǒng)的運(yùn)行狀況進(jìn)行跟蹤。在python中，我們不需要第三方的日志組件，因?yàn)樗呀?jīng)為我們提供了簡(jiǎn)單易用、且功能強(qiáng)大的日志模塊：logging。

python 打印對(duì)象的所有屬性值：

def prn_obj(obj):
  print '\n'.join(['%s:%s' % item for item in obj.__dict__.items()])

Python logger對(duì)象屬性（由上述函數(shù)獲取的）

name:get_data
parent:<logging.RootLogger instance at 0x1d8bd88>
handlers:[<logging.FileHandler instance at 0x21bcc68>]
level:10
disabled:1   #當(dāng)前的logger是否有效，默認(rèn)為0
manager:<logging.Manager instance at 0x1d8bea8>
propagate:0   #是否將本級(jí)日志
filters:[]

部分日志無(wú)法輸出

File：logger.conf

 
[formatters]
keys=default
 
[formatter_default]
format=%(asctime)s - %(name)s - %(levelname)s - %(message)s
class=logging.Formatter
 
[handlers]
keys=console, error_file
 
[handler_console]
class=logging.StreamHandler
formatter=default
args=tuple()
 
[handler_error_file]
class=logging.FileHandler
level=INFO
formatter=default
args=("logger.log", "a")
 
[loggers]
keys=root
 
[logger_root]
level=DEBUG
formatter=default
handlers=console,error_file

File：logger.py

 
#!/bin/env python
 
import logging
from logging.config import logging
 
class Test(object):
  """docstring for Test"""
  def __init__(self):
    logging.config.fileConfig("logger.conf")
    self.logger = logging.getLogger(__name__)
 
  def test_func(self):
    self.logger.error('test_func function')
 
class Worker(object):
  """docstring for Worker"""
  def __init__(self):
    logging.config.fileConfig("logger.conf")
    self.logger = logging.getLogger(__name__)
 
    data_logger = logging.getLogger('data')
    handler = logging.FileHandler('./data.log')
    fmt = logging.Formatter('%(asctime)s|%(message)s')
    handler.setFormatter(fmt)
    data_logger.addHandler(handler)
    data_logger.setLevel(logging.DEBUG)
    self.data_logger = data_logger
 
  def test_logger(self):
    self.data_logger.error("test_logger function")
    instance = Test()
    self.data_logger.error("test_logger output")
    instance.test_func()
 
 
def main():
  worker = Worker()
  worker.test_logger()
 
if __name__ == '__main__':
  main()

問(wèn)題一：測(cè)試過(guò)程中，只能打印出test_logger function一條語(yǔ)句
問(wèn)題二：明明只在data_logger中打印出語(yǔ)句，但是logger的日志中也出現(xiàn)了相關(guān)的日志。

問(wèn)題一解決方案：

利用python -m pdb logger.py 語(yǔ)句對(duì)腳本進(jìn)行調(diào)試發(fā)現(xiàn)，在執(zhí)行instance = Test()語(yǔ)句后，通過(guò)print '\n'.join(['%s:%s' % item for item in self.data_logger.__dict__.items()])調(diào)試語(yǔ)句看到data_logger的disable屬性值由0變成了True，此時(shí)logger的對(duì)應(yīng)屬性也發(fā)生了相同的變化。這種變化導(dǎo)致了logger對(duì)象停止記錄日志。參考python logging模塊的相關(guān)手冊(cè)發(fā)現(xiàn)“The fileConfig() function takes a default parameter, disable_existing_loggers, which defaults to True for reasons of backward compatibility. This may or may not be what you want, since it will cause any loggers existing before the fileConfig() call to be disabled unless they (or an ancestor) are explicitly named in the configuration.” 的說(shuō)明，即調(diào)用fileconfig()函數(shù)會(huì)將之前存在的所有l(wèi)ogger禁用。在python 2.7版本該fileConfig()函數(shù)添加了一個(gè)參數(shù)，logging.config.fileConfig(fname, defaults=None, disable_existing_loggers=True)，可以顯式的將disable_existing_loggers設(shè)置為FALSE來(lái)避免將原有的logger禁用。將上述代碼中的Test類中的logging.config.fileConfig函數(shù)改成logging.config.fileConfig("./logger.conf", disable_existing_loggers=0)就可以解決問(wèn)題。不過(guò)該代碼中由于位于同一程序內(nèi)，可以直接用logging.getLogger(LOGGOR_NAME)函數(shù)引用同一個(gè)logger，不用再調(diào)用logging.config.fileConfig函數(shù)重新加載一遍了。

問(wèn)題二解決方案：

logger對(duì)象有個(gè)屬性propagate，如果這個(gè)屬性為True，就會(huì)將要輸出的信息推送給該logger的所有上級(jí)logger，這些上級(jí)logger所對(duì)應(yīng)的handlers就會(huì)把接收到的信息打印到關(guān)聯(lián)的日志中。logger.conf配置文件中配置了相關(guān)的root logger的屬性，這個(gè)root logger就是默認(rèn)的logger日志。

修改后的如下：

File：logger.conf

 
[formatters]
keys=default, data
 
[formatter_default]
format=%(asctime)s - %(name)s - %(levelname)s - %(message)s
class=logging.Formatter
 
[formatter_data]
format=%(asctime)s|%(message)s
class=logging.Formatter
 
[handlers]
keys=console, error_file, data_file
 
[handler_console]
class=logging.StreamHandler
formatter=default
args=tuple()
 
[handler_error_file]
class=logging.FileHandler
level=INFO
formatter=default
args=("logger.log", "a")
 
[handler_data_file]
class=logging.FileHandler
level=INFO
formatter=data
args=("data_new.log", "a")
 
[loggers]
keys=root, data
 
[logger_root]
level=DEBUG
handlers=console,error_file
 
[logger_data]
level=DEBUG
handlers=data_file
qualname=data
propagate=0

File：logger.py

 
#!/bin/env python
 
import logging
from logging.config import logging
 
class Test(object):
  """docstring for Test"""
  def __init__(self):
    self.logger = logging.getLogger(__name__)
 
  def test_func(self):
    self.logger.error('test_func function')
 
class Worker(object):
  """docstring for Worker"""
  def __init__(self):
    logging.config.fileConfig("logger.conf")
    self.logger = logging.getLogger(__name__)
    self.data_logger = logging.getLogger('data')
 
  def test_logger(self):
    self.data_logger.error("test_logger function")
    instance = Test()
    self.data_logger.error("test_logger output")
    instance.test_func()
 
 
def main():
  worker = Worker()
  worker.test_logger()
 
if __name__ == '__main__':
  main()

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