title: How to use log4j's FileAppenders asynchronously?
body: <p>I work on a low-latency trading application. We'd like to increase the amount of lof4j logging that we write to file, whilst minimising the impact on our end-to-end processing time. </p>
  
  <p>What is the recommended way of doing this? I think FileAppender.append is synchronous, so we need to do something a bit smarter than that....</p>