How to use log4j's FileAppenders asynchronousl

Question

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.

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....

Answer 1

Yes, the appenders are synchronous. You want something like this:

http://www.spartanjava.com/2009/asynchronous-logging-with-log4j/

Answer 2

If you need to log from a multithreaded application slf4j and its implementation logback are much better choice.

Answer 3

bear in mind that AsyncAppender adds a thread per appender & that increasing the amount of logging you do may mean a substantial increase in the amount of string concatentation going on which often means a substantial amount of string processing/munging/formatting which can be pretty expensive (relative to the latency involved in a low latency trading app anyway).