# The Log4j feature

Talend supports Log4j on all components, which presents a technical logging mechanism. For more information on how to enable it for all components, see [Customizing log4j output level at runtime](https://help.qlik.com/talend/r/en-US/8.0/studio-user-guide/customizing-log4j-output-level-at-runtime).

After Log4j is enabled, you can set the level of logging need for the Job. Log4j provides these logging levels: Trace, Debug, Info, Warn, Error, and Fatal. ![](https://help.qlik.com/talend/en-US/debug-jobs/Resources/images/log4jlevels.png)

Information noteNote: To use the Log4j feature, you need to enable the feature in the Log4j pane of the Project Settings dialog box in Talend Studio. ![](https://help.qlik.com/talend/en-US/debug-jobs/Resources/images/log4j2.png)

To check the data values flowing through your subJob, set Log4jLevel to **Trace**. The data for all of the rows then displays in the console. ![](https://help.qlik.com/talend/en-US/debug-jobs/Resources/images/log4jlevel_trace.png)

As in the previous examples, if one of the fields has a **null** value that leads to a null pointer exception, you'll be able to see it in the console log. ![](https://help.qlik.com/talend/en-US/debug-jobs/Resources/images/log4jlevel_error_in_console.png)