I don't seem to have the ability to update the ticket, so I figured I'd comment instead.

I just took a closer look at AppenderBase, and I noticed that doAppend() is a synchronized method. Since we probably don't want that for AsyncAppender, I take back my recommendation that we change AsyncAppender to inherit from AppenderBase. Instead, we probably should just focus on tweaking UnsynchronizedAppenderBase. What does everyone think?