gradle - Execute in parallel

exec_parallel.gradle

#!groovy

/*
* based on http://www.tothenew.com/blog/how-to-use-thread-pooling-using-groovy/
*/

import java.util.concurrent.Callable
import java.util.concurrent.Executors
import java.util.concurrent.Future

// Create a Closure that receives :
//  @params       -> a list of parameters to be passed to exec_closure
//  @executors    -> number of executors to use (number of parallel tasks)
//  @exec_closure -> the closure to be executed to each one of the params
def exec_parallel = { params, executors, exec_closure ->
    def threadPool = Executors.newFixedThreadPool(executors)
    try {
        List<Future> futures = params.collect { param ->
            threadPool.submit({ ->
                exec_closure param
            } as Callable);
        }
        // recommended to use following statement to ensure the execution of all tasks.
        futures.each { it.get() }
    } finally {
        threadPool.shutdown()
    }
}

// Example
task parallel << {

    exec_parallel ([ ['You say', 'goodbye'], ['I say', 'hello'] ], 4) { it1, it2 ->
        println "$it1 $it2"
    }
    
}