Parallel4 is a easy-to-use multi-threading API for Java an other JVM based languages like Groovy. It offers parallel versions of the "for" and "foreach" loops to leverage the full power of todays multi-core CPUs.

Parallel4's goals are:

* Simple API: Hide as many details of multi-threaded programming as possible from the API. Although it does not offer transparent/implicit multi-threading in a strict sense, it tries to come as close to this as a non-functional programming language allows.
* Familiar API: Offer well known constructs, e.g. the "for" loop and add parallelism to it.
* Easy adaptation of parallel programming: Based on a familiar API, it is easy to introduce multi-threading. Often, two additional lines of code are enough without imposing any structural changes.
* Adaptive: Let the "framework" make reasonable defaults to adapt to the execution environment, e.g. use as many threads as CPU cores are available.
* Performance: A low overhead makes it easy to decide whether to use parallel processing or not.
* Reliable: Multi-threading gets tricky when things go wrong unexpectedly. A well defined exception handling makes this a bit easier.