Log4J - When to configure?

[Scott Selikoff]

Each class in my project establishes a logger with the call:

private static final Logger log = Logger.getLogger(<ClassName>.class)

I'd like to configure the Log4J using the call with:

DOMConfigurator.configure(fileName)

Question, when should this call be made? Is the order that it happens relevant to when Logger.getLoger() is called?

The reason I ask is the pattern used in my code wraps Logger.getLogger(...) in a helper class that calls DOMConfigurator.configure(...) each time the Logger.getLogger(...) and I think I'm hitting an intermittent concurrency issue of some kind from the frequent calls to configure made by each class as it instatiates. The logger start ups fine, but stops writing to disk early in the startup process. A subsequent call to DOMConfigurator.configure() can reestablish the logger writing ability, but I'd like to know why it sometimes loses the ability to write to disk on startup.

[Scott Selikoff]

Nevermind about the concurrency issue, found the cause, still not sure when configure() should be called. Before any loggers initialize, after, or does it not really matter?

[Paul Clapham]

Call it as soon as possible. Log4j will initialize itself as soon as it can, i.e. as soon as you first do that. It isn't possible for you to do that before log4j's initialization.