Apache Log4j

Apache Log4j is an open source toolkit developed by the famous Apache Software Foundation that lets developers watch various facets of their Java application and/or website.

Log4j is ideal for running logging and tracing jobs for applications, letting developers record what happens at runtime and save it for later analysis and debugging.

Extremely important for most developers that have ever worked with Java, this library works using a set of simple components.

There are components (Java classes) for managing the logging configuration, logging filters, and the logging operation itself.

Support for classic log levels is included, along with the possibility to append new logging events and filters at runtime based on the program's evolution.

The 2.x branch of is incompatible with its predecessor, 1.x.

Versions of this library are also available for PHP and .NET environments.

What is new in this release:

• Fixed issue where Async Logger does not log thread context stack data. API Added method getImmutableStackOrNull() to ThreadContext.ContextStack interface.
• Update docs to clarify how to use formatter logger and standard logger together.
• Added support for generating custom logger wrappers that replace the existing log levels and extended logger wrappers that add custom log levels to the existing ones.
• LoggerConfigs with no Level now inherit the Level from their parent.
• Android: Could not find class 'javax.naming.InitialContext', referenced from method org.apache.logging.log4j.core.lookup.JndiLookup.lookup.
• RegexFilter does not match multiline log messages.
• PatternLayout manual page missing documentation on header/footer.
• Fixed Serialization error with SocketAppender and Async Loggers. (Fixed in RC2, but wasn't included in release notes.)
• JMX GUI: fixed occasional ArrayIndexOutOfBoundsException after pressing "reconfigure with XML below". (Fixed in RC2, but wasn't included in release notes.)
• AsyncLoggerContextSelector should ensure that different AsyncLoggerContext objects created by web app classloaders have unique names.
• Fixed annotation processor warnings on JDK 1.7+.
• Fixed strange compilation error that popped up in a test class.

What is new in version 2.3:

• Fixed issue where Async Logger does not log thread context stack data. API Added method getImmutableStackOrNull() to ThreadContext.ContextStack interface.
• Update docs to clarify how to use formatter logger and standard logger together.
• Added support for generating custom logger wrappers that replace the existing log levels and extended logger wrappers that add custom log levels to the existing ones.
• LoggerConfigs with no Level now inherit the Level from their parent.
• Android: Could not find class 'javax.naming.InitialContext', referenced from method org.apache.logging.log4j.core.lookup.JndiLookup.lookup.
• RegexFilter does not match multiline log messages.
• PatternLayout manual page missing documentation on header/footer.
• Fixed Serialization error with SocketAppender and Async Loggers. (Fixed in RC2, but wasn't included in release notes.)
• JMX GUI: fixed occasional ArrayIndexOutOfBoundsException after pressing "reconfigure with XML below". (Fixed in RC2, but wasn't included in release notes.)
• AsyncLoggerContextSelector should ensure that different AsyncLoggerContext objects created by web app classloaders have unique names.
• Fixed annotation processor warnings on JDK 1.7+.
• Fixed strange compilation error that popped up in a test class.

What is new in version 2.2:

• Fixed issue where Async Logger does not log thread context stack data. API Added method getImmutableStackOrNull() to ThreadContext.ContextStack interface.
• Update docs to clarify how to use formatter logger and standard logger together.
• Added support for generating custom logger wrappers that replace the existing log levels and extended logger wrappers that add custom log levels to the existing ones.
• LoggerConfigs with no Level now inherit the Level from their parent.
• Android: Could not find class 'javax.naming.InitialContext', referenced from method org.apache.logging.log4j.core.lookup.JndiLookup.lookup.
• RegexFilter does not match multiline log messages.
• PatternLayout manual page missing documentation on header/footer.
• Fixed Serialization error with SocketAppender and Async Loggers. (Fixed in RC2, but wasn't included in release notes.)
• JMX GUI: fixed occasional ArrayIndexOutOfBoundsException after pressing "reconfigure with XML below". (Fixed in RC2, but wasn't included in release notes.)
• AsyncLoggerContextSelector should ensure that different AsyncLoggerContext objects created by web app classloaders have unique names.
• Fixed annotation processor warnings on JDK 1.7+.
• Fixed strange compilation error that popped up in a test class.

What is new in version 2.0-beta3:

• Added interval and modulate options to TimeBasedTriggeringPolicy to allow more fine-grained control of when file rolling should occur.
• Added support for filtering packages from stack traces.
• If system property "disableThreadContextStack" is set pushes to the ThreadContext will be ignored. If system property "disableThreadContext" is set both puts and pushes will be ignored.
• If system property "disableThreadContextMap" is set puts to the ThreadContext
• will be ignored. If system property "disableThreadContext" is set both puts and pushes will be ignored.
• Added support for ANSI colors by adding the highlight and style pattern converters. Fixed pattern parsing to allow nested patterns.
• Allowed the status logging to be directed to stderr or to a file.
• Added getFormats to MultiformatMessage and allow StructuredDataMessage to format as XML.

What is new in version 1.2.17:

• log4j 1.2.17 release preparation.
• Configure from an InputStream.
• JDBCAppender not closed due to SQL Exception while executing an
• SQL.
• Memoryleak - org.apache.log4j.helpers.ThreadLocalMap.
• DOMConfigurator does not close input stream when configured based
• on URL.
• javadoc.jar was missing NOTICE and LICENSE and contained .svn
• entries.
• Wrong log levels logged with serialized LoggingEvent.

What is new in version 1.2.16:

• TelnetAppender misses messages when one of many clients disconnect.
• Javadoc class index corrupted by JDBCAppender deprecation warning.
• Agent.java is sole dependency on jmxtools.jar with Java 5+.
• Javadoc for Appender.getName implies that the return value will be unique and not null.
• More Debug output for log4j auto-configure requested.

Requirements:

• Java 6 or higher