The Apache Log4j 2 team is pleased to announce the Log4j 2.9 release!

Apache Log4j is a well known framework for logging application behavior. Log4j 2 is an upgrade
to Log4j that provides significant improvements over its predecessor, Log4j 1.x, and provides
many other modern features such as support for Markers, lambda expressions for lazy logging,
property substitution using Lookups, multiple patterns on a PatternLayout and asynchronous
Loggers. Another notable Log4j 2 feature is the ability to be "garbage-free" (avoid allocating
temporary objects) while logging. In addition, Log4j 2 will not lose events while reconfiguring.

This release contains the first support of Java 9 as well as bugfixes and minor
enhancements. The Log4j API was modified to use java.util.ServiceLoader to locate Log4j implementations,
although the former binding mechanism is still supported. The Log4j jar is now a multi-release jar
to provide implementations of the Java 9 specific classes. Multi-release jars are not supported by
the OSGi specification so OSGi modules will not be able to take advantage of these implementations
but will not lose functionality as they will fall back to the implementations used in Java 7 and 8.
More details on the new features and fixes are itemized below.

Note that subsequent to the 2.9 release, for security reasons, SerializedLayout is deprecated and no
longer used as default in the Socket and JMS appenders. SerializedLayout can still be used as before,
but has to be specified explicitly. To retain old behaviour, you have to change configuration like:

into:

We do, however, discourage the use of SerializedLayout and recommend JsonLayout as a replacement:

Note that subsequent to the 2.9 release, for security reasons, Log4j does not process DTD in XML files.
If you used DTD for including snippets, you have to use XInclude or Composite Configuration instead.

The Log4j 2.9.0 API, as well as many core components, maintains binary compatibility with previous releases.

GA Release 2.9.0

Changes in this version include:

New Features

  • LOG4J2-2008
    Support printing multiple StructuredData elements in RFC5424Layout.
  • LOG4J2-1986
    Public API for parsing the output from JsonLayout/XmlLayout/YamlLayout into a LogEvent.
  • LOG4J2-1981
    JsonLayout, XmlLayout and YamlLayout support 0-byte termination of log events.
  • LOG4J2-1864
    Support capped collections for MongoDb appender. Thanks to Matthias Kappeller.
  • LOG4J2-1813
    Log4j2 will now print all internal logging to the console if system property `log4j2.debug` is defined with any value (or no value).
  • LOG4J2-1766
    Temporary compress directory during rollover (#88). Thanks to Pierrick HYMBERT.
  • LOG4J2-1814
    Added wrapper classes CustomLoggerGenerator and ExtendedLoggerGenerator to avoid class name with a dollar ($) character which has special meaning in many unix command line environments.
  • LOG4J2-1884
    Added process ID (pid) pattern converter.
  • LOG4J2-1699
    Configurable Log File Permissions with PosixFilePermission. Thanks to Demetrios Dimatos, Pierrick HYMBERT.
  • LOG4J2-1945
    Generate source jas for all test jars.
  • LOG4J2-1934
    JMS Appender does not know how to recover from a broken connection.
  • LOG4J2-1955
    JMS Appender should be able connect to a broker (later) even it is not present at configuration time.
  • LOG4J2-1874
    Added methods ::writeBytes(ByteBuffer) and ::writeBytes(byte[], int, int) to ByteBufferDestination interface and use these methods in TextEncoderHelper where possible to prepare for future enhancements to reduce lock contention. Thanks to Roman Leventov.
  • LOG4J2-1442
    Generic HTTP appender.
  • LOG4J2-1442
    Add with(String, primitive) methods to org.apache.logging.log4j.message.MapMessage.
  • LOG4J2-1930
    Add forEach() methods to org.apache.logging.log4j.message.MapMessage.
  • LOG4J2-1932
    Add containsKey() methods to org.apache.logging.log4j.message.MapMessage.
  • LOG4J2-1854
    Support null byte delimiter in GelfLayout. Thanks to Xavier Jodoin.
  • LOG4J2-1359
    Add support for Java 9 StackWalker.
  • LOG4J2-1880
    Warn when a configuration file for an inactive ConfigurationFactory is found.
  • LOG4J2-1855
    Add an optional random delay in TimeBasedTriggeringPolicy Thanks to Anthony Maire.
  • LOG4J2-1860
    Shortcut to add Property and KeyValuePair component in ConfigurationBuilder.
  • LOG4J2-1294
    The JMS Appender should use a JMS MapMessage for a Log4j MapMessage.

Fixed Bugs

  • LOG4J2-1833
    Prevent NullPointerException when a file name is specified with the DirectWriteRolloverStrategy.
  • LOG4J2-2018
    Fix incorrect documentation for LoggerNameLevelRewritePolicy.
  • LOG4J2-922
    Parameter of mdcId in SyslogAppender has no default value. Thanks to angus.aqlu, Paul Burrowes.
  • LOG4J2-2001
    StyleConverter.newInstance argument validation is incorrect. Thanks to Paul Burrowes.
  • LOG4J2-1999
    HighlightConverter converts all unrecognized levels to DEBUG. Thanks to Paul Burrowes.
  • LOG4J2-2013
    SslSocketManager does not apply SSLContext on TCP reconnect. Thanks to Taylor Patton, Gary Gregory.
  • LOG4J2-2016
    Mark FileRenameAction as successful when using alternative ways to move files. Thanks to Benjamin Jaton.
  • LOG4J2-2012
    No compression when using a separate drive in Linux. Thanks to Benjamin Jaton.
  • LOG4J2-1888
    Log4j throws a java.nio.charset.UnsupportedCharsetException: cp65001. Thanks to Misagh Moayyed.
  • LOG4J2-1990
    ConcurrentModificationException logging a parameter of type Map. Thanks to Philippe Mouawad.
  • LOG4J2-1311
    SocketAppender will lose several events after re-connection to server. Thanks to Xibing Liang.
  • LOG4J2-1977
    Consider the StringBuilder's capacity instead of content length when trimming. Thanks to Jerry xnslong.
  • LOG4J2-1971
    Register log4j-core as an OSGi service. Skip tests for LOG4J2-1766 on MacOS. Use group "staff" for LOG4J2-1699 test on MacOS.
  • LOG4J2-1994
    TcpSocketServer does not close accepted Sockets.
  • LOG4J2-1987
    Log4J JUL Bridge and RMI Security Manager causes access denied ("java.util.logging.LoggingPermission" "control") Thanks to Andreas Felder.
  • LOG4J2-1982
    Log4j-config.xsd only allows one AppenderRef element for each Logger element. Thanks to Christoph Lembeck.
  • LOG4J2-1985
    Fix default buffer size to match documentation (from 8102 to 8192 a.k.a. 8KB.) Thanks to Kenneth McFarland.
  • LOG4J2-1912
    CompositeConfiguration logs warning "Unable to determine URI for configuration." However, the reconfiguration is completed. Thanks to R Ri.
  • LOG4J2-1964
    Dynamic reconfiguration does not work for filePattern of RollingFile. Thanks to Pierrick HYMBERT.
  • LOG4J2-1961
    Reconfigure breaks DirectWriteRolloverStrategy. Thanks to Christian Vent.
  • LOG4J2-1943
    The eventPrefix attribute was being ignored in the RFC5424Layout.
  • LOG4J2-1953
    JndiManager is not released when the JmsAppender builder catches an exception trying to build itself.
  • LOG4J2-1911
    Improve the documentation of the DynamicThresholdFilter.
  • LOG4J2-1929
    EOFException with FormattedMessage. Thanks to Borys Sokolov.
  • LOG4J2-1948
    Trim levels read from properties file to remove trailing spaces. Thanks to Michael Luck.
  • LOG4J2-1971
    ClassCastException: org.eclipse.osgi.internal.loader.SystemBundleLoader$1 cannot be cast to java.lang.ClassLoader. Thanks to liwenxian2017.
  • LOG4J2-1876
    More reliable checking for runtime dependencies.
  • LOG4J2-1867
    Fix configuration documentation.
  • LOG4J2-1858
    Ensure the ThreadLocal StringBuilder in ParameterizedMessage won't hold excessively much memory after logging a long message.
  • LOG4J2-1885
    Fix documentation about default additivity value for loggers.
  • LOG4J2-1920
    ScriptEngineManager is not available in Android and causes a NoClassDefFoundError. Thanks to Ajitha.
  • LOG4J2-1989
    Clarify Javadoc for AbstractTriggeringPolicy. Thanks to Kenneth McFarland.
  • LOG4J2-1993
    Fix compiler warnings in LoggerConfigTest. Thanks to Kenneth McFarland.

Changes

  • LOG4J2-2011
    Replaced JCommander with picocli command line parser to let users run Log4j2 utility applications without requiring an external dependency.
  • LOG4J2-1928
    Add support for DirectWriteRolloverStrategy to RollingRandomAcessFileAppender.
  • LOG4J2-2022
    RFC5424Layout now prints the process id.
  • LOG4J2-2020
    Remove default layout from KafkaAppender.
  • LOG4J2-2023
    Use a class' canonical name instead of name to create its logger name.
  • LOG4J2-2015
    Allow KeyStoreConfiguration and TrustStoreConfiguration to find files as resources.
  • LOG4J2-1984
    Allow maxLength of StructuredData to be specified by the user.
  • LOG4J2-1071
    Allow for bufferSize=0 in SMTP appender. Thanks to Ben Ludkiewicz, Benjamin Jaton.
  • LOG4J2-1261
    Async Loggers no longer use deprecated LMAX Disruptor APIs. (Disruptor-3.3.3 or higher is now required.)
  • LOG4J2-1908
    Improved error message when misconfigured with multiple incompatible appenders targeting same file.
  • LOG4J2-1954
    Configurations with multiple root loggers now fail loudly.
  • LOG4J2-1958
    Deprecate SerializedLayout and remove it as default.
  • LOG4J2-1959
    Disable DTD processing in XML configuration files.
  • LOG4J2-1950
    Fix docker build with jdk9 requirements (#84). Thanks to Pierrick HYMBERT.
  • LOG4J2-1801
    Add more detail to WARN "Ignoring log event" messages printed to the console after log4j was shut down.
  • LOG4J2-1926
    Facilitate log4j use in Android applications: remove dependency on RMI and Management APIs from log4j-api.
  • LOG4J2-1956
    JMS Appender broker password should be a char[], not a String.
  • LOG4J2-1917
    Support using java.util.ServiceLoader to locate Log4j 2 API providers.
  • LOG4J2-1966
    Include separator option of PatternLayout in manual (and other updates). Thanks to M Sazzadul Hoque.
  • LOG4J2-1851
    Move server components from log4j-core to new log4-server module.
  • LOG4J2-1991
    Refactor SimpleMessage to be concise and clear (#100) Thanks to .
  • LOG4J2-2017
    Update Jackson from 2.8.9 to 2.9.0.
  • LOG4J2-1868
    Update ZeroMQ's JeroMQ from 0.3.6 to 0.4.0.
  • LOG4J2-1960
    Update ZeroMQ's JeroMQ from 0.4.0 to 0.4.1.
  • LOG4J2-1974
    Update ZeroMQ's JeroMQ from 0.4.1 to 0.4.2.
  • LOG4J2-1869
    Update Kafka client from 0.10.1.1 to 0.10.2.0
  • LOG4J2-1962
    Update Kafka client from 0.10.2.0 to 0.11.0.0
  • LOG4J2-1872
    Update JavaMail from 1.5.5 to 1.5.6.
  • LOG4J2-1879
    Update JAnsi from 1.14 to 1.15.
  • LOG4J2-1877
    Missing documentation for Max index limit in DefaultRolloverStrategy. Thanks to Chandra Tungathurthi.
  • LOG4J2-1899
    Add missing getters to classes in package org.apache.logging.log4j.core.net.ssl.
  • LOG4J2-1900
    Update JAnsi from 1.15 to 1.16.
  • LOG4J2-](https
    Update SLF4J from 1.7.24 to 1.7.25.
  • LOG4J2-1938
    Update Jackson from 2.8.7 to 2.8.9.
  • LOG4J2-1970
    Update HdrHistogram from 2.1.8 to 2.1.9.
  • LOG4J2-1975
    Update javax.persistence from 2.1.0 to 2.1.1.
  • LOG4J2-1976
    Update org.osgi.core from 4.3.1 to 6.0.0.

Apache Log4j 2.9.0 requires a minimum of Java 7 to build and run. Log4j 2.3 was the last release that supported Java 6.

Basic compatibility with Log4j 1.x is provided through the log4j-1.2-api component, however it does not implement some of the very implementation specific classes and methods. The package names and Maven groupId have been changed to org.apache.logging.log4j to avoid any conflicts with log4j 1.x.

For complete information on Apache Log4j 2, including instructions on how to submit bug reports, patches, or suggestions for improvement, see the Apache Apache Log4j 2 website:

http://logging.apache.org/log4j/2.x/