是什么导致日志记录模块多次记录一条记录? [英] What could cause the logging module to log a record multiple times?

问题描述

我有一个多线程Python应用程序，它使用了内置于日志记录中模块.为了控制日志记录级别并使以后更容易将StreamHandler与FileHandler交换，我创建了一个通用的辅助函数，每个模块都调用该函数来创建相同的记录器(名称除外).

I have a multi-threaded Python application that makes use of the built in logging module. To control the logging levels and make it easier to swap the StreamHandler with a FileHandler in the future, I have created a common helper function called by each module to create an identical logger (other than its name).

如何解决此问题?

关键点

1. 项目中的每个模块都有其自己的记录器实例.
2. 示例输出是通过一次调用记录器(self._logger.info("Logger Setup"))
生成的
3. 我尝试包括当前线程名称(threading.Thread.getName())，它可以确认同一线程正在调用，从而导致多个日志.

1. Each module in the project has its own logger instance.
2. The sample output is generated by a single call to a logger (self._logger.info("Logger Setup"))
3. I have tried including the current thread name (threading.Thread.getName()) and it confirms that the same thread is calling causing the multiple logs.

创建记录器-现在可以使用

import logging
import sys
def createSystemLogHandler(logger):
    # This is now called once at the logger's root 
    ch = logging.StreamHandler(sys.stdout) # Normal output is to stderr which doesn't show up on Window's CMD
    format = logging.Formatter('%(asctime)s - %(levelname)s - %(name)s - %(message)s')
    ch.setFormatter(format)
    logger.addHandler(ch)
    return logger

def configureSystemLogger(name='', level=logging.WARNING):
        logger = logging.getLogger(name)
        logger.setLevel(level)
        logger.info("Logger Setup")
        return logger

示例输出

2012-04-25 21:59:40,720 - INFO - HW_MGR - Logger Setup
2012-04-25 21:59:40,720 - INFO - HW_MGR - Logger Setup
2012-04-25 21:59:40,720 - INFO - HW_MGR - Logger Setup
2012-04-25 21:59:40,720 - INFO - HW_MGR - Logger Setup
2012-04-25 21:59:40,720 - INFO - HW_MGR - Logger Setup

推荐答案

我的猜测是您有多个处理程序(即，一条消息被多次发出；但是在重新阅读您的问题时，看起来像您已经知道).要调试，请尝试:

My guess is that you've got multiple handlers (ie, one message is being emitted multiple times; but on re-reading your question, it looks like you already knew that). To debug that, try:

• 查看logging.getLogger("").handlers(即根记录器上的处理程序)
• 检查您对addHandler()
的呼叫
• 布兰登·罗德(Brandon Rhode) pdb 来跟踪日志消息的生命周期(即，放置一个断点)恰好在调用self._logger.info(…)之前，然后进入该函数).

• Looking at logging.getLogger("").handlers (ie, the handlers on the root logger)
• Checking your calls to addHandler()
• Brandon Rhode's logging_tree module
• Use pdb to trace a log message's lifecycle (ie, put a breakpoint just before a call to self._logger.info(…), then step into that function).

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