log4j add logs in different files based on logged in user of the application

Question

I am using log4j.1.2.16 for logging in my Java application hosted in tomcat. Given below is my log4j.properties

##DEBUG < INFO < WARN < ERROR < FATAL
#### Use two appenders, one to log to console, another to log to a file
log4j.rootCategory=DEBUG, R

#### Appender writes to a file
log4j.appender.R=org.apache.log4j.RollingFileAppender
log4j.appender.R.File=${APP_HOME}/runtime/log/em.log

# Control the maximum log file size
log4j.appender.R.MaxFileSize=100MB
# Archive log files (one backup file here)
log4j.appender.R.MaxBackupIndex=20

log4j.appender.R.layout=org.apache.log4j.PatternLayout
log4j.appender.R.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} [%p] %c{1} %m%n

log4j.logger.com.mchange=WARN
log4j.logger.com.amazonaws=WARN
log4j.logger.org.hibernate=ERROR
log4j.logger.org.apache.commons.beanutils=WARN
log4j.logger.org.apache.commons.httpclient=WARN
log4j.logger.org.elasticsearch=WARN
log4j.category.velocity=WARN
log4j.com.amazonaws.services.s3=WARN
log4j.org.apache.http.impl.conn.Wire=WARN
log4j.logger.httpclient.wire.header=WARN
log4j.logger.httpclient.wire.content=WARN

I want to maintain different log files for different users(of the same application). For example if user1 logs in to my application I want the logs to go into user1.log file . I will be having loggedin user information in the session object and a static thread local variable. How can I achieve this ?

Answer 1

Here are few ways to achieve this.

1. You can make use ofRoutingAppender to achieve this.
2. Configure the Logging Programmatically like mentioned here .
3. If you can change to Logback, You can think of MDC with SiftingAppender .

Note : Many of these solutions require you to set the UserId in a shared context like MDC or ThreadContext, so make sure you clear it out after the request processing.