Hi All I have a log4j properties something like the below. Everything that is logged in TextProcessor.log is something is above above WARN level. I don't understand the threshold that is set here to debug. Can someone explain what the threshold does
What does threshold mean in Log4J? This will help you to debug the code as by default it will print out on the console (default console appender is on).
Thanks in advance
Mridang Agarwalla4 Answers
You have two things here : a logger, and an appender. Unfortunately, you chose the same name for both, which doesn't make it very clear.
The logger's minimum level is set to warn, which means everything you log with this logger which doesn't have at least the warn level will be ignored.
Once a message is accepted by the logger, it's sent to one or several appenders (to a file, to the console, to a mail server, etc.). Each of these appenders may define a threshold. You could for example limit the messages in the console to errors, but accept warn messages in the log file.
JB NizetJB NizetThreshold is second filter for messages to be logged
e.g.:
if Logger is set at level DEBUG and appender Threshold is set at Error then with the appender TextProcessor only Error and higher severity messages would be logged.
Use of Threshold is ,you can define different appender with different threshold levels ,for e.g in above mentioned example you can also have InfoLogger with Info level messages logging enabled
To understand levels , There are below levels of logging in log4j:
go to URL for more details
The levels of logging are TRACE, DEBUG, INFO, WARN, ERROR and FATAL. You will be able to choose what to log at what level in the code depending on the severity. For example you will have the ability to log entry and exit of methods but can choose to log at the DEBUG level. This will help you to debug the code as by default it will print out on the console (default console appender is on). While going to production you can increase the threshold to ERROR and prevent the application from printing out not so useful details on the console or log files.
Give you simple mapping from properties config file to flow of log messages. (I hid some lines of config to minimize)
To understand what it is, you should know that:
- The levels of logging increase when retrieving to the leftmost: TRACE, DEBUG, INFO, WARN, ERROR and FATAL
- Minimum level logging which logger accepts from application.
- Minimum level logging on appender which decides what will be written
** There are some thing more complex about inheritance and additivity, but you should start at basic and simple things first.
Ken BlockKen BlockNot the answer you're looking for? Browse other questions tagged javalogginglog4j or ask your own question.
Is there any way to tell to log4j to write its log to the file and to the console?thanksthere are my properties:
fatnjazzyfatnjazzyLog4j Consoleappender Xml
4 Answers
Your root logger definition is a bit confused.See the log4j documentation.
This is a standard Java properties file, which means that lines are treated as key=value pairs. Your second log4j.rootLogger line is overwriting the first, which explains why you aren't seeing anything on the console appender.
You need to merge your two rootLogger definitions into one. It looks like you're trying to have DEBUG messages go to the console and INFO messages to the file. The root logger can only have one level, so you need to change your configuration so that the appenders have appropriate levels.
While I haven't verified that this is correct, I'd guess it'll look something like this:
Note that you also have an error in casing - you have console lowercase in one place and in CAPS in another.
Steven SchlanskerSteven SchlanskerYour log4j File should look something like below read comments.
user295691Log4j Consoleappender
Log4j File Appender Date In Filename
Write the root logger as below for logging on both console and FILE
log4j.rootLogger=ERROR,console,FILE
And write the respective definitions like Target, Layout, and ConversionPattern (MaxFileSize for file etc).