Log4j 2 is an open-source logging library for Java applications, and it is the successor to the popular Log4j 1.x framework. It is designed to be fast, flexible, and modular, with features and configurations to meet the demands of modern software development.
Log4j 2 is built on top of the Apache Logging Services Project, which provides a general-purpose logging framework for Java. It supports a wide range of logging outputs, including console, file, network, and database. Additionally, it offers a number of advanced features, such as asynchronous logging, garbage-free logging, and automatic configuration through various formats, such as XML, JSON, and properties files.
Log4j 2 also has a more sophisticated API than its predecessor, which allows for more control over logging configuration and behavior. It supports multiple logging levels, which allow developers to control the granularity of log messages, as well as custom log levels that can be defined and used in the application. It also provides support for various logging appenders, which allow developers to specify where log messages are sent.
Overall, Log4j 2 is a powerful and flexible logging library that can help developers to troubleshoot and debug Java applications by providing valuable information about the application’s runtime behavior.