Log4j2, set log level at runtime for Thread specific

Question

We have a webserver and multiple users log in to it. We generally put log level to ERROR or INFO level. But sometimes, for debugging purpose, we need to see logs. There is one way to set it at runtime, but this process is not so good in case of loads of traffic. Important logs will be missed and also we don't know for how much time we need to keep it that way. I have written a wrapper in log4j v1.2, which just ignores the level check if userid belongs to some TestUsersList. So, it opens all logs for a particular user[a thread] only. A snippet is below-

public void trace(Object message) {
    Object diagValue = MDC.get(LoggerConstants.IS_ANALYZER_NUMBER);
    if (valueToMatch.equals(diagValue)) { // Some condition to check test number
        forcedLog(FQCN, Level.TRACE, message, null);
        return;
    }
    if (repository.isDisabled(Level.TRACE_INT))
        return;
    if (Level.TRACE.isGreaterOrEqual(this.getEffectiveLevel()))
        forcedLog(FQCN, Level.TRACE, message, null);
}

But now I have moved to log4j2, I don't want to write this wrapper again. Is there any inbuilt functionality which log4j2 provides for this?

score 1 · Answer 1 · answered Aug 18 '16 at 18:43

This can be done with filters. Add a logger to the configuration that logs all the messages you want, then add a ThreadContextMapFilter that has a KeyValuePair for each user you want to log.

Then put the user ids in the Thread Context within the code.

Log4j2, set log level at runtime for Thread specific

1 Answers1