withPool(1) {pool ->  //feel free to experiment with the number of fork/join threads in the pool
    println """Number of files: ${
        runForkJoin(new File("./src")) {file ->
            long count = 0
            file.eachFile {
                if (it.isDirectory()) {
                    println "Forking a child task for $it"
                    forkOffChild(it)           //fork a child task
                } else {
                    count++
                }
            }
            return count + (childrenResults.sum(0))
            //use results of children tasks to calculate and store own result
        }
    }"""
}

public final class FileCounter extends AbstractForkJoinWorker<Long> {
    private final File file;
    def FileCounter(final File file) {
        this.file = file
    }
    protected void compute() {
        long count = 0;
        file.eachFile {
            if (it.isDirectory()) {
                println "Forking a thread for $it"
                forkOffChild(new FileCounter(it))           //fork a child task
            } else {
                count++
            }
        }
        setResult(count + ((childrenResults)?.sum() ?: 0))  //use results of children tasks to calculate and store own result
    }
}
withPool(1) {pool ->  //feel free to experiment with the number of fork/join threads in the pool
    println "Number of files: ${orchestrate(new FileCounter(new File("..")))}"
}