1. GoAccess, a real-time analysis tool for website logs
http://www.vpsee.com/2014/02/a-real-time-web-log-analyzer-goaccess/
2. Monitor and collect Java application performance data through logs (Perf4J)
http://www.ibm.com/developerworks/cn/java/j-lo-logforperf/
3.log.io
Like other monitoring tools, log.io uses a server-client model. log.io consists of two parts: server and harvester, server runs on machine A (server) to monitor and record log messages sent by other machines; log harvester runs on machine B (client) to monitor and collect machine B log changes on and send the changes to machine A , each machine that needs to record the log needs a harvester.
http://www.blogjava.net/ldwblog/archive/2012/11/06/390886.html
https://github.com/NarrativeScience/Log.io/tree/master/src