Data Parallelism - Java 8 Lambdas - page 93

thread pool. None of these issues needs to be directly addressed when using the parallel
streams library.

Example 6-4. Simulating dice rolls by manually implementing threading
public public class class ManualDiceRolls ManualDiceRolls {

private private static static final final int int N = 100000000 ;

private private final final double double fraction ;

private private final final Map < Integer , Double > results ;

private private final final int int numberOfThreads ;

private private final final ExecutorService executor ;

private private final final int int workPerThread ;

public public static void main ( String [] args ) {

ManualDiceRolls roles = new

static void

new ManualDiceRolls ();
roles . simulateDiceRoles ();

}

public public ManualDiceRolls () {

fraction = 1.0 / N ;
results = new new ConcurrentHashMap <>();

numberOfThreads = Runtime . getRuntime (). availableProcessors ();
executor = Executors . newFixedThreadPool ( numberOfThreads );
workPerThread = N / numberOfThreads ;

}

public public void void simulateDiceRoles () {

List < Future <?>> futures = submitJobs ();
awaitCompletion ( futures );
printResults ();

}

private private void void printResults () {

results . entrySet ()
. forEach ( System . out :: println );

}

private private List < Future <?>> submitJobs () {

List < Future <?>> futures = new

new ArrayList <>();

for for ( int int i = 0 ; i < numberOfThreads ; i ++) {

futures . add ( executor . submit ( makeJob ()));

}
return

return futures ;

}