repeated logging in log 4j in java

Question

I used log4j in a java program. I initialized it with :

BasicConfigurator.configure(); // logger configuration
try {
     logger.setLevel(Level.DEBUG);
} catch (Exception e) {
     System.out.println("Logfile not found");
}

But, during the execution of the program i get 3 log statements instead of one. For example,

3 lines 
1047 [main] INFO ibis.Preproc.Ratings  - Added AS TIMEZONE to tZones[0] = GMT-12:00
1047 [main] INFO ibis.Preproc.Ratings  - Added AS TIMEZONE to tZones[0] = GMT-12:00
1047 [main] INFO ibis.Preproc.Ratings  - Added AS TIMEZONE to tZones[0] = GMT-12:00

instead of one line

1047 [main] INFO ibis.Preproc.Ratings  - Added AS TIMEZONE to tZones[0] = GMT-12:00

Are there any extra configurations to be done to log4j to avoid this?

Answer 1

Well, you haven't shown how your program is executing. Here's a complete program which only shows a single line:

import org.apache.log4j.*;

public class Test
{
    public static void main(String[] args)
    {
        BasicConfigurator.configure(); // logger configuration
        Logger logger = Logger.getLogger(Test.class);
        logger.setLevel(Level.DEBUG);
        logger.info("Hello");
    }
}

Is it possible that your code really is running three times?

Answer 2

I've experienced similar behavior, and it turned out that Log4J was configured more than once; using the BasicConfigurator, but also with a log4j.xml file I had forgotten about. Could it be that there's an additional Log4J configuration somewhere on the classpath?

Answer 3

Most probably you have more than one Appenders. See the log4j manual (Section: Appenders and Layouts):

Each enabled logging request for a given logger will be forwarded to all the appenders in that logger as well as the appenders higher in the hierarchy.

You can try setting the additivity flag to false.