Log4j: Conditional additivity (or propagate event to root logger based on condition?)

Question

I've very simple task: write all events (warn and above) to main log and for certain logger write debug only messages to second log file (warn and above must be logged to main). Sometimes I wish to see debug messages in main log as well (eg log4j.logger.com.test=debug)

Besides I must use log4j properties file syntax. I don't understand if additivity (see my last line) can be conditional in that case or should I use complete different approach for the task (which one?).

What I've for now:

log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.EnhancedPatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d %-5p [%t] %c:%L - %m%n

log4j.rootLogger=warn, stdout

log4j.appender.file2=org.apache.log4j.RollingFileAppender
log4j.appender.file2.maxFileSize=10240KB
log4j.appender.file2.maxBackupIndex=30
log4j.appender.file2.File=${catalina.home}/logs/test.log
log4j.appender.file2.encoding=UTF-8
log4j.appender.file2.layout=org.apache.log4j.PatternLayout
log4j.appender.file2.layout.ConversionPattern=%d %-5p [%t] %c:%L - %m%n
log4j.logger.org.hibernate = debug, file2
log4j.additivity.org.hibernate = false

log4j.logger.com.test=debug

Answer 1

I would recommend you look at Log4J2 as log4j1.x is no longer actively maintained (and Log4J2 has several other advantages like performance improvements).

A common use case is writing debug and higher (info,warn, error, fatal) to a file for developers and warn and higher (warn, error, fatal) to another file eg for support.

From your description it sounds like you want to restrict output to only debug level, and exclude info, warn, error and fatal-level messages. This is possible but not as straight-forward as the use case above. You probably need to use filters: http://logging.apache.org/log4j/2.x/manual/filters.html Take a look at the filter documentation, I'll see if I can dig up an example.