Simplifiying java.util.concurrent with Groovy

02 April 2008

Tags: concurrent groovy java

Ever wondered how to simplify java.util.concurrent usage with Groovy ? Here’s a simple example of what can be easily done using closures. The following code executes several closures in parallel and waits upon completion before resuming the script.

def doInParallel(Closure... closures) {
 def service = java.util.concurrent.Executors.newFixedThreadPool(closures.length)
 def latch = new java.util.concurrent.CountDownLatch(closures.length)
 closures.each { cl -> service.execute({
  try {
   cl.call()
  } catch (e) {
   throw e
  } finally {
   latch.countDown()
  }
 })}
 latch.await()
 service.shutdown()
}

Here’s how to use it :

doInParallel(
   { println 1+1 },
   { callVeryLongProcess() },
   { throw Exception() } // demonstrates the correct handling of exceptions
)

println "This line of code will only appear after every closure in doInParallel is completed"

Fun, isn’t it ?