Python Logging Module Usage Guide: Solving Common Problems

python Logging, recording, debugging, monitoring

Solution to common problems

1. How to set up basic configuration?

import logging

# 设置基本配置
logging.basicConfig(
level=logging.INFO,
fORMat="%(asctime)s %(levelname)s: %(message)s"
)

2. How to use different log levels?

logging.debug("这是一个调试消息")
logging.info("这是一个信息消息")
logging.warning("这是一个警告消息")
logging.error("这是一个错误消息")
logging.critical("这是一个严重错误消息")

3. How to create a custom logger?

# 创建一个名为 "my_custom_logger" 的记录器
my_logger = logging.getLogger("my_custom_logger")
my_logger.setLevel(logging.INFO)

# 创建一个文件处理程序
file_handler = logging.FileHandler("my_app.log")
file_handler.setLevel(logging.INFO)

# 创建一个流处理程序
stream_handler = logging.StreamHandler()
stream_handler.setLevel(logging.INFO)

# 为记录器添加处理程序
my_logger.addHandler(file_handler)
my_logger.addHandler(stream_handler)

my_logger.info("这是一个自定义记录的消息")

4. How to configure the log format?

logging.basicConfig(
level=logging.INFO,
format="[%(asctime)s] %(levelname)s %(name)s: %(message)s"
)

5. How to use log filter?

# 创建一个过滤器，仅记录来自 "my_custom_logger" 记录器的警告消息
my_filter = logging.Filter()
my_filter.filter = lambda record: record.name == "my_custom_logger" and record.levelno == logging.WARNING

# 为记录器添加过滤器
my_logger.addFilter(my_filter)

6. How to catch unhandled exception?

import sys

# 为 unhandled 异常设置一个处理程序
logging.basicConfig(
level=logging.ERROR,
format="[%(asctime)s] %(levelname)s %(name)s: %(message)s",
handlers=[logging.StreamHandler(sys.stderr)]
)

# 触发一个 unhandled 异常
raise Exception("这是一个 unhandled 异常")

7. How to enable thread-safe logging?

import logging
import threading

# 为 thread-safe 日志记录设置一个处理程序
logging.basicConfig(
level=logging.INFO,
format="[%(asctime)s] %(levelname)s %(name)s: %(message)s",
handlers=[logging.StreamHandler()],
concurrent=True
)

# 创建一个线程并记录消息
def my_thread():
logging.info("这是一个来自线程的消息")

# 启动线程
thread = threading.Thread(target=my_thread)
thread.start()
thread.join()

8. How to configure the logging configuration file?

Create a file named "logging.conf" and place it in the application directory:

import logging.config

# 导入 logging 配置文件
logging.config.fileConfig("logging.conf")

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