Log4J does not log anything

Question

I just picked up an existing web application at work that is supposed to log its activity using Log4J. I've configured my workspace exactly as I was told to and everything else (db connection, authentication, etc...) works fine except that the nothing is being written to the log file. Other similar applications have no problem logging.

I've looked at the WebSphere console when the application starts up and there are no errors there that might indicate why Log4J isn't logging.

I mentioned this to another dev (who once worked on this application, but not for a while and is more out of date than I am on it) who remarked that it was very strange behaviour, but had no idea why it might fail to log and not report any errors.

I've gone over the config file and properties file and everything looks OK. I suspect that Log4J is never even reading the log4j.xml but I'm not certain of that. It's been a while since I've worked with Log4J - does anyone have some good tips on trouble-shooting this type of problem?

PS: There are instances of this application that are deployed to various test/QA/prod servers and these instances all log fine. It's only on local workstations that logging seems to silently fail.

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Update: So it does seem to be a problem with the way the application is being deployed. I changed the classloader mode to "Parent Last" and I can see that the Log4J file is at least being read now. And the first action I attempt triggers a ClassNotFoundException saying that org.apache.commons.logging.impl.Log4jFactory cannot be found.

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2nd Update: I've noticed something stranger... The application has two WAR projects - one of them is for the UI and the other is for some web services. The project that is for the UI is successfully logging its operations to the log file. The web service project is the one that fails with the ClassNotFoundException. Both of them have commons-logging.jar listed as a JavaEE module dependency, and neither of them have a project-specific logging configuration (all config files are in a Resources project).

A major difference is that that UI project includes some other in-house frameworks (pre-compiled as JARs) that might already include necessary logging configurations and maybe that's where the difference is.

I also tried to use the answer (a file named org.apache.commons.logging.LogFactory in the META-INF/services with one line containing: "org.apache.commons.logging.impl.Log4jFactory") from this question: Websphere all logs are going to SystemOut.log but it did not seem to help.

Solution 1

The most recent thing I changed that finally got logging working properly was changing the classloader mode to "PARENT_FIRST" and WAR classloader policy to "Application". The initial default configuration was "PARENT_FIRST"/"Module". I changed it to "PARENT_LAST"/"Application" on the advice of a co-worker who says logging works fine for them and this is the only change they have to make when they create a new sandbox for this application. I'm not sure why I had to go with "PARENT_FIRST"/"Application", but at least it works now.

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UPDATE:

I tried setting up a new workspace and I had the same problem. It turns out you need "PARENT_FIRST"/"Application" AND a file named org.apache.commons.logging.LogFactory in the META-INF/services with one line containing: "org.apache.commons.logging.impl.Log4jFactory". Not having the file causes logging to fail (typically with a message saying that a Log4J cannot be found).

Solution 2

See this answer: How to initialize log4j properly?

-Dlog4j.debug is very useful for problems like this