AsynchronousAppender.Dispatcher error handling

["Hebert, Marc" <Ma...@arrisi.com>]

Hello.

I've been a happy user of log4j for years- only recently have I been prompted to look at the source code as after running our software under a load test for about a day, I see all logging threads come to an abrupt halt.

I'm still gathering info on the problem, but I think I figured out what's going on in a general sense and thought I'd mention here what I know so far.  I'm using 1.2.15.

Quite simply, my AsyncAppender.Dispatcher thread is throwing an uncaught exception.  My (j2ee/jboss) application is configured to log uncaught exceptions, and attempting to log from the Dispatcher thread in this state not surprisingly causes a deadlock - while the DispatcherThread is trying to acquire a lock on the RootLogger, the thread owning it is waiting on AsyncAppender's buffer lock, which I think is owned by the Dispatcher.

I've instrumented the code a bit and the next time I can reproduce this I should find out what exception AsyncAppender.Dispatcher is encountering, but regardless I expect it should be getting caught, especially on a system configured to log uncaught exceptions.  Right now I'm simply catching throwable, System.out'ing about it, and then exiting the Dispatcher thread, which will just make all future logging synchronous.

If anyone with more experience in the code has a better idea on how to react to exceptions encountered in the Dispatcher thread, I'd love to hear them.  Of course, once I know what exception is happening I'll try to address it as well, but I also need all possible safeguards in place against my system grinding to a halt because of it.

Marc