解決Python logging模組無法正常輸出日誌的問題
廢話少說,先上程式碼
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()
問題一:測試過程中,只能打印出test_logger function一條語句
問題二:明明只在data_logger中打印出語句,但是logger的日誌中也出現了相關的日誌。
問題一解決方案:
利用python -m pdb logger.py 語句對指令碼進行除錯發現,在執行instance = Test()語句後,通過print '\n'.join(['%s:%s' % item for item in self.data_logger.__dict__.items()])除錯語句看到data_logger的disable屬性值由0變成了True,此時logger的對應屬性也發生了相同的變化。這種變化導致了logger物件停止記錄日誌。
參考python logging模組的相關手冊發現
“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.”
的說明,即呼叫fileconfig()函式會將之前存在的所有logger禁用。
在python 2.7版本該fileConfig()函式添加了一個引數,logging.config.fileConfig(fname,defaults=None,disable_existing_loggers=True),可以顯式的將disable_existing_loggers設定為FALSE來避免將原有的logger禁用。
將上述程式碼中的Test類中的logging.config.fileConfig函式改成logging.config.fileConfig("./logger.conf",disable_existing_loggers=0)就可以解決問題。
不過該程式碼中由於位於同一程式內,可以直接用logging.getLogger(LOGGOR_NAME)函式引用同一個logger,不用再呼叫logging.config.fileConfig函式重新載入一遍了。
問題二解決方案:
logger物件有個屬性propagate,如果這個屬性為True,就會將要輸出的資訊推送給該logger的所有上級logger,這些上級logger所對應的handlers就會把接收到的資訊列印到關聯的日誌中。logger.conf配置檔案中配置了相關的root logger的屬性,這個root logger就是預設的logger日誌。
修改後的如下:
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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