Comparison between Semaphore and executor

JarProcessor

import java.io.File;
import java.io.IOException;
import java.util.Enumeration;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Semaphore;
import java.util.concurrent.TimeUnit;
import java.util.zip.ZipEntry;
import java.util.zip.ZipException;
import java.util.zip.ZipFile;

public class JarProcessor {

	public static void main(String[] args) {
// there are 4 jars in the directory , number of entries in jar = [12, 203, 1178, 1551]
		File dir = new File("/home/karan/jars");
//		processWithSemaphore(dir);
		processWithExecutor(dir);
	}
	private static void processWithSemaphore(File dir) {
		final ConcurrentLinkedQueue<Integer> queue = new ConcurrentLinkedQueue<Integer>();
		final int total = 4;

		final Semaphore threads = new Semaphore(total);

		try {

			long ps = System.nanoTime();

			for (final File file : dir.listFiles()) {
				if (!file.isFile())
					continue;

				threads.acquire();

				// FORK

				Thread runnable = new Thread() {
					public void run() {

						try {

							// ++++++++++++++++++++++++++++++++++
							// do some heavy lifting with 'file'
							// ++++++++++++++++++++++++++++++++++
							queue.add(new ComputeSize().compute(file));
						} catch (Exception e) {

							System.out.println("FAILED Task "
									+ file.getAbsolutePath());

						} finally {

							threads.release();

						}
					}
				};
				runnable.setDaemon(true);
				runnable.start();
			}

			// JOIN

			try {
				threads.acquire(total);
			} catch (InterruptedException e) {
				Thread.interrupted();
			}

			// DONE

			System.out.println("FINISHED" + " "
					+ TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - ps));
			System.out.println(queue);

		} catch (InterruptedException e) {
			Thread.interrupted();
			throw new RuntimeException("processing failed", e);
		}
	}
	private static void processWithExecutor(File dir) {
		final ConcurrentLinkedQueue<Integer> queue = new ConcurrentLinkedQueue<Integer>();
ExecutorService exec = Executors.newFixedThreadPool(4);

		
		try {
			
			long ps = System.nanoTime();
			
			for (final File file : dir.listFiles()) {
				if (!file.isFile())
					continue;
				
				exec.execute(new Runnable() {
					public void run() {
						
						try {
							
							// ++++++++++++++++++++++++++++++++++
							// do some heavy lifting with 'file'
							// ++++++++++++++++++++++++++++++++++
							queue.add(new ComputeSize().compute(file));
						} catch (Exception e) {
							
							System.out.println("FAILED Task "
									+ file.getAbsolutePath());
							
						} 
					}
				});
			}
			
			exec.shutdown();
			exec.awaitTermination(Long.MAX_VALUE, TimeUnit.SECONDS);
			// DONE
			
			System.out.println("FINISHED" + " "
					+ TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - ps));
			System.out.println(queue);
			
		} catch (InterruptedException e) {
			Thread.interrupted();
			throw new RuntimeException("processing failed", e);
		}
	}
}
class ComputeSize{
	public int compute(File file) throws ZipException, IOException{
		int size = 0;
		for (int i = 0; i < 1000; i++) {
			ZipFile zipFile = new ZipFile(file);
			Enumeration<? extends ZipEntry> entries = zipFile.entries();
			while (entries.hasMoreElements()) {
				ZipEntry zipEntry = (ZipEntry) entries.nextElement();
				size++;
			}
		}
		return size;
	}
}