Develop Reference

How to find out which Log4j configuration is loaded?

We're using Log4j (via Slf4j) for logging.
Our log4j configuration is rather simple:
<?xml version="1.0" encoding="UTF-8"?>
<Configuration>
<Appenders>
<Console name="Console">
<PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n"/>
</Console>
</Appenders>
<Loggers>
<Root level="INFO">
<AppenderRef ref="Console"/>
</Root>
<Logger name="net.sf.jsi.rtree.RTree" level="INFO">
<AppenderRef ref="Console"/>
</Logger>
</Loggers>
</Configuration>
Note that root logger is set to INFO.
However, we're getting a huge amount of DEBUG logs from a third-party library (net.sf.jsi). Logs we're absolutely not interested in.
My guess is that there's a different Log4j configuration on the classpath somewhere which gets picked up and sets root logger to DEBUG.
My question is, how could I found which configuration is actually loaded and used by log4j?
Update:
I have seen this "possible duplicate". However, the answer which suggests to use -Dlog4j.debug does not work for me.
I've added -Dlog4j.debug to the VM arguments. I only get:
DEBUG StatusLogger org.slf4j.helpers.Log4jLoggerFactory is not on classpath. Good!
DEBUG StatusLogger Using ShutdownCallbackRegistry class org.apache.logging.log4j.core.util.DefaultShutdownCallbackRegistry
WARN StatusLogger Multiple logging implementations found:
Factory: org.apache.logging.log4j.core.impl.Log4jContextFactory, Weighting: 10
Factory: org.apache.logging.slf4j.SLF4JLoggerContextFactory, Weighting: 15
Using factory: org.apache.logging.slf4j.SLF4JLoggerContextFactory
which is not enough info for me.

Log4j2 - Why is my "Logger" element hiding content from my "Root" logger?

Before someone closes this question off as a duplicate, just hear me out... I have read through countless blog posts, tutorials, FAQs and SO questions for days now and I'm no closer to understanding why I'm getting this specific behaviour.
Configuration
My log4j2.xml config file contains the following:
<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="DEBUG">
<Properties>
<Property name="APP_NAME">MyCoolApp</Property>
<Property name="BASE_PACKAGE">my.cool.package</Property>
<Property name="LOG_DIR">${env:LOG_ROOT:-logs}</Property>
<Property name="LOG_PATTERN">%d [%t] %-5level %c{1.}:%L:%M | %m%n</Property>
</Properties>
<Appenders>
<RollingFile name="AppLogFile" fileName="${LOG_DIR}/${APP_NAME}.log" filePattern="${LOG_DIR}/archive/${APP_NAME}.%d{yyyy-MM-dd}.log.gz">
<PatternLayout pattern="${LOG_PATTERN}"/>
<TimeBasedTriggeringPolicy/>
</RollingFile>
<Console name="Console" target="SYSTEM_OUT">
<PatternLayout pattern="${LOG_PATTERN}"/>
</Console>
</Appenders>
<Loggers>
<Logger name="${BASE_PACKAGE}" level="INFO">
<AppenderRef ref="AppLogFile"/>
</Logger>
<Root level="TRACE">
<AppenderRef ref="Console"/>
</Root>
</Loggers>
</Configuration>
Then each class initialises a logger with private static final Logger LOGGER = LogManager.getLogger();.
Runtime
From my understanding of log levels, loggers and appenders, this should give me the following:
All INFO and higher level logging output to file
All TRACE and higher level logging output to console
Meanwhile, if I run the app when the AppLogFile appender is enabled, I get less output to the console; counting from only after the Log4j initialisation, I get 255 lines compared to 367.
Looking through the console and file output, when the AppLogFile appender is enabled, I don't get any TRACE or DEBUG output, only INFO and higher. When I comment out just that appender (without changing anything else), then I get everything to console, including TRACE and DEBUG.
I've tried playing around with reordering the "console" and "file" related elements, I've tried explicitly enabling and disabling the logger's additivity property, I've tried using filters in the appenders and loggers, and even multiple appender references inside one logger with explicit level properties.
All I want is to get everything to go to the console and everything INFO level and higher to go to a file. What am I missing here..?

The level attribute and the <AppenderRef> element are entirely independent:
Specifying level changes the logging level of the given logger and all sub-loggers.
Specifying <AppenderRef> adds1 another appender to the given logger and all sub-loggers.
The fact that you do both at the same time, doesn't affect those independent effects.
If you want to limit log entries for the Appender, specify the level attribute on the <AppenderRef> instead.
1) If you wanted the Appender to replace, you need to specify additivity="false"
(OP edit) Just for the sake of clarity, between what I learned from this answer and the Log4j2 FAQ; I streamlined things a bit and ended up with the following <Loggers> configuration:
<Loggers>
<Root level="TRACE">
<AppenderRef ref="AppLogFile" level="INFO"/>
<AppenderRef ref="Console"/>
</Root>
</Loggers>

How can I specify a specific format for each Log4j log level

First time trying to use log4j version log4j-1.2.17.jar.
On an existing application the client has log4j in place and there is a log4j.properties file which specifies a light log output. What I want to do is depending on the log level (ERROR & WARN) output a more refined entry.
On the log4j site I came across this but I think it is to be in some .xml file. I need some assistance in understanding how I can put in place the formatting option to alter based on log level.
You don't need to declare separate loggers to achieve this. You can set the logging level on the AppenderRef element.
<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="WARN">
<Appenders>
<File name="file" fileName="app.log">
<PatternLayout>
<Pattern>%d %p %c{1.} [%t] %m %ex%n</Pattern>
</PatternLayout>
</File>
<Console name="STDOUT" target="SYSTEM_OUT">
<PatternLayout pattern="%m%n"/>
</Console>
</Appenders>
<Loggers>
<Root level="trace">
<AppenderRef ref="file" level="DEBUG"/>
<AppenderRef ref="STDOUT" level="INFO"/>
</Root>
</Loggers>
</Configuration>
Would I put this xml content into the web.xml file or another file?
a) If another file what file name and where would it go?
How do I get log4j to realize that I need it to use the xml file?
Will the use of the xml ignore the log4j.properties file?
I know it is a lot of questions but there is only me on the project and the client has a production crisis that needs to be figured out today so I don't have time to go off to read and do tutorials with the client calling me every hour. I figured it may help to get this logging more useful. As the logs are right now I have a date and message output to the log but no idea where the entries are created from without doing extensive searches through the code.

You could do this by defining multiple non-additive Loggers so that the first one only logs errors, the next one warnings and the final one infos and debug.

Log4j2 Servlet 3.0 not logging

I have a JAX-RS 2.0 application running on a Tomcat 7 server, and I'm using log4j2 along with SLF4J to record the server logs to a file.
I can't seem to get any logs to show up properly in my log file when running the server in production, although when I run my integration tests, logs are output correctly.
In production, the logs are merely redirected to the console instead.
My log4j2.xml file is located in the WEB-INF/classes folder, and I've included all the necessary dependencies as well.
My configuration file looks like this:
<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="trace">
<Appenders>
<Console name="Console" target="SYSTEM_OUT">
<PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n"/>
</Console>
<RollingFile name="file" fileName="log/trace.log" append="true" filePattern="log/trace.%i.log">
<PatternLayout pattern="%d{yyyy-MM-dd HH:mm:ss.SSS} [%t] %-5level %X %logger{36} - %msg%n"/>
<Policies>
<OnStartupTriggeringPolicy/>
<SizeBasedTriggeringPolicy size="10 MB" />
</Policies>
</RollingFile>
</Appenders>
<Loggers>
<Logger name="my.package" level="TRACE" additivity="false">
<AppenderRef ref="file"/>
</Logger>
<Root level="WARN">
<AppenderRef ref="file"/>
</Root>
</Loggers>
</Configuration>
The web.xml needs no configuration (I'm following the documentation found on the log4j2 website).
EDIT
I've tried setting the Root level to TRACE but everything still gets redirected to console. The file log/trace.log itself is created, it's just never written to. I also tried setting immediateFlush=true but that didn't have any impact either.

I noticed you have status logging (log4j internal logging) set to TRACE. This will dump log4j internal initialization messages to the console. It this what you mean?
Otherwise, the config you provide shows there is no logger that has an appender-ref pointing to the ConsoleAppender.
So, if you are also seeing your application logs being output to the console (in addition to log4j's status log messages), I suspect there is another log4j2.xml (or log4j2-test.xml) config file in the classpath somewhere.
Fortunately log4j's status logs should also show the location of the log4j config file, so you can confirm which config file is actually being loaded.
You can switch off status logging by setting <Configuration status="WARN"> after confirming all works correctly.

I figured it out!
Turns out I was using the gretty plug-in with gradle, which contains it's own logging package (the logback library).
It used it's own internal logback.xml which was redirecting to console. I fixed this by overwriting the internal logback.xml with my own (using logback's configuration) and now everything works as expected!

Log4J2 and Tomee Plus 7.0.47 not working

According to here, Log4j2 should work with Tomcat7.0.47. I'm using TomEE Plus 7.0.47.
I have a webapplication deployed with a log4j2.xml in my web-inf/classes folder. This is the config:
<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="WARN">
<Appenders>
<Console name="Console" target="SYSTEM_OUT">
<PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n"/>
</Console>
<File name="File" fileName="${sys:catalina.home}/logs/testapp.log">
<PatternLayout>
<pattern>%d %p %C{1.} [%t] %m%n</pattern>
</PatternLayout>
</File>
</Appenders>
<Loggers>
<Logger name="org.alex" level="TRACE" additivity="false">
<AppenderRef ref="File"/>
</Logger>
<Root level="INFO">
<AppenderRef ref="Console"/>
</Root>
</Loggers>
</Configuration>
I have a logger declared in a class with name org.alex.util.JSON:
private static final Logger LOG = LoggerFactory.getLogger(JSON.class);
I'm using slf4j-api 1.7.5, and have the following libs added to the tomcat lib:
slf4j-api-1.7.5.jar
log4j-api-2.0-rc1.jar
log4j-core-2.0-rc1.jar
log4j-slf4j-impl-2.0-rc1.jar
If I change the Configuration status to TRACE, I can see my configuration file being picked up and configuration happens as expected. Also I can see the MBeans being added.
However, there's not one logging statement ending up in my logfile. I debugged into the log4j2 Logger, and see that the isEnabled(...) method returns false because the logger (com.alex.util.JSON) has the level "ERROR" set, while the configuration set the package org.alex to TRACE.
Further investigation shows it uses a DefaultConfiguration configured for level=ERROR, and only root is configured. I'm thinking of a classloader issue, but I can't seem to figure out what the cause is and how to solve it.
Does anyone know what I'm doing wrong?

This should work on trunk
Btw saw log4j2 has hacks for tomcat and since tomee wraps classloaders not sure they work as expected...

This is very strange. Please raise a ticket for this in the Log4j2 issue tracker so the Log4j team can take a look.
The problem may go away if you put the jar files you mentioned inside WEB-INF/lib instead of in Tomcat's lib folder.

To be comple log4j2 relies on servletcontainerinitializer which are called after ejb and app scanning so ejbs can be loaded too early. Doing the same with a tomcat context listener would make it working better