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[id=log4j2.contextSelector]
== `log4j2.contextSelector`

[cols="1h,5"]
|===
| Env. variable
| `LOG4J_CONTEXT_SELECTOR`

| Type
| link:../javadoc/log4j-core/org/apache/logging/log4j/core/selector/ContextSelector.html[`Class<? extends ContextSelector>`]

| Default value
|
link:../javadoc/log4j-core/org/apache/logging/log4j/core/selector/ClassLoaderContextSelector.html[`ClassLoaderContextSelector`]

(on Android)
link:../javadoc/log4j-core/org/apache/logging/log4j/core/selector/BasicContextSelector.html[`BasicContextSelector`]
|===

Specifies the fully qualified class name of the
link:../javadoc/log4j-core/org/apache/logging/log4j/core/selector/ContextSelector.html[`ContextSelector`]
implementation to use.

The implementations available by default are:

link:../javadoc/log4j-core/org/apache/logging/log4j/core/selector/BasicContextSelector.html[`org.apache.logging.log4j.core.selector.BasicContextSelector`]::
Creates a single logger context and synchronous loggers

link:../javadoc/log4j-core/org/apache/logging/log4j/core/async/BasicAsyncLoggerContextSelector.html[`org.apache.logging.log4j.core.async.BasicAsyncLoggerContextSelector`]::
Creates a single logger context and xref:manual/async.adoc[asynchronous loggers]

link:../javadoc/log4j-core/org/apache/logging/log4j/core/selector/ClassLoaderContextSelector.html[`org.apache.logging.log4j.core.selector.ClassLoaderContextSelector`]::
Creates a separate logger context per classloader and synchronous loggers

link:../javadoc/log4j-core/org/apache/logging/log4j/core/async/AsyncLoggerContextSelector.html[`org.apache.logging.log4j.core.async.AsyncLoggerContextSelector`]::
Creates a separate logger context per classloader and xref:manual/async.adoc[asynchronous loggers]

link:../javadoc/log4j-core/org/apache/logging/log4j/core/osgi/BundleContextSelector.html[`org.apache.logging.log4j.core.osgi.BundleContextSelector`]::
Creates a separate logger context per OSGi bundle and synchronous loggers

link:../javadoc/log4j-core/org/apache/logging/log4j/core/selector/JndiContextSelector.html[`org.apache.logging.log4j.core.selector.JndiContextSelector`]::
Creates loggers contexts based on a JNDI lookup and synchronous loggers See xref:jakarta.adoc#jndi-configuration[Web application] for details.

There are also third-party context selector implementations:

[IMPORTANT]
====
These context selectors are provided by **third-party** vendors and are not maintained by the
link:{logging-services-url}[Apache Logging Services]
(Log4j, Log4cxx, Log4net) project.
====

https://oss.copernik.eu/tomcat/3.x/components/log4j-tomcat#TomcatContextSelector[`eu.copernik.log4j.tomcat.TomcatContextSelector`]::
Selects the currently active Tomcat web application and creates synchronous loggers.

https://oss.copernik.eu/tomcat/3.x/components/log4j-tomcat#TomcatContextSelector[`eu.copernik.log4j.tomcat.TomcatAsyncContextSelector`]::
Selects the currently active Tomcat web application and creates xref:manual/async.adoc[asynchronous loggers].