Concurrency with Groovy

Using threads and AtomicInteger

From Groovy you can use all of the normal concurrency facilities in Java and combine them with threads and closures as necessary. E.g. from a Groovy example http://www.thecoderscorner.com/articleGen/show/4?page=2:

Fibonacci with Executors

A Groovy script to naively calculate the Fibonacci series inspired by the example here.
Note: a version using memoizing will be much more efficient but this illustrates using Java's built-in concurrency primitives from Groovy.

Which produces this:

Calculating Fibonacci sequence in parallel...
n=8 => 21
n=9 => 34
n=10 => 55
n=11 => 89
n=12 => 144
n=13 => 233
n=14 => 377
n=15 => 610
n=16 => 987

If you want to convince yourself that some threads are actually being created, replace the last each line with:

which will add something like the following to your output:

Thread[Finalizer,8,system]
Thread[Reference Handler,10,system]
Thread[TimerQueue,5,system]
Thread[pool-1-thread-2,5,main]
Thread[Thread-3,6,main]
Thread[Thread-2,6,main]
Thread[pool-1-thread-3,5,main]
Thread[AWT-Shutdown,5,main]
Thread[Signal Dispatcher,9,system]
Thread[Attach Listener,5,system]
Thread[AWT-EventQueue-0,6,main]
Thread[DestroyJavaVM,5,main]
Thread[pool-1-thread-1,5,main]
Thread[Java2D Disposer,10,system]
Thread[pool-1-thread-5,5,main]
Thread[pool-1-thread-6,5,main]
Thread[pool-1-thread-4,5,main]
Thread[AWT-Windows,6,main]

Fibonacci with Functional Java

If you wish to make use of the functionaljava (tested with 2.1.3) library (see the link to the original example), you could use a Groovy program such as this: