Expiration is a project mainly written in Scala, it's free.
benchmarking ExpirationService
This is a microbenchmark for an "ExpirationService" which is a thing that keeps track of items that need to expire, such as an Akka Future.
You could run it like this for example:
sbt stageJAVA_OPTS='-XX:+UseSerialGC -Xmx2048M' target/start