This program takes input files sequentially but all tasks execute in parallel using a single core. The execution time for all tasks is longer than sequential execution time. I want to reduce the execution time using multiple cores by executing the tasks in parallel. How can I do that? How can I use multi-core in this program? I want to use at least two cores.
package TestParallel;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectOutputStream;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.crypto.Cipher;
import javax.crypto.CipherOutputStream;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
/**
*
* @author Sohel Rana
*/
public class Executor {
public void encrypt(File fname) throws Exception {
System.out.println("Encryption Started : " + System.currentTimeMillis() + " File Name : " + fname);
KeyGenerator keyGen = KeyGenerator.getInstance("AES");
keyGen.init(256); //using AES-256
SecretKey key = keyGen.generateKey(); //generating key
// System.out.println("Key = " + bytesToHex(key.getEncoded()));
Cipher aesCipher = Cipher.getInstance("AES"); //getting cipher for AES
aesCipher.init(Cipher.ENCRYPT_MODE, key); //initializing cipher for encryption with key
//creating file output stream to write to file
try (FileOutputStream fos = new FileOutputStream(fname + ".aes")) {
//creating object output stream to write objects to file
ObjectOutputStream oos = new ObjectOutputStream(fos);
oos.writeObject(key); //saving key to file for use during decryption
//creating file input stream to read contents for encryption
try (FileInputStream fis = new FileInputStream(fname)) {
//creating cipher output stream to write encrypted contents
try (CipherOutputStream cos = new CipherOutputStream(fos, aesCipher)) {
int read;
byte buf[] = new byte[4096];
while ((read = fis.read(buf)) != -1) //reading from file
{
cos.write(buf, 0, read); //encrypting and writing to file
}
}
}
System.out.print("\nComplete Time = " + System.currentTimeMillis());
System.out.println(" \tand file task complete :" + fname);
// fname.delete();
}
}
public static void main(final String[] args) throws InterruptedException {
// final ExecutorService pool = Executors.newFixedThreadPool(4);
int cores = Runtime.getRuntime().availableProcessors();
System.out.println("Available processor cores is " + cores);
File file1 = new File("C:\\Users\\Sohel Rana\\Desktop\\test\\Khushnuma Official Video HD - Suyyash Rai & Kishwer Merchant_HD.mp4");
File file2 = new File("C:\\Users\\Sohel Rana\\Desktop\\test\\EK MULAQAT - Sonali Cable HD.mp4");
File file3 = new File("C:\\Users\\Sohel Rana\\Desktop\\test\\Java Cryptography Tutorials 1 AES Encryption and Decryption using Java.mp4");
File file4 = new File("C:\\Users\\Sohel Rana\\Desktop\\test\\01. Nath Nath.MP4");
Executor ex = new Executor();
final ExecutorService executor = Executors.newFixedThreadPool(cores);
long startTime = System.currentTimeMillis();
for (File f : new File[]{file1, file2, file3, file4}) {
startTime = System.currentTimeMillis();
executor.execute(() -> {
try {
ex.encrypt(f);
//System.out.println(f);
} catch (Exception ex1) {
Logger.getLogger(Executor.class.getName()).log(Level.SEVERE, null, ex1);
}
});
}
executor.shutdown();
if (executor.awaitTermination(1, TimeUnit.DAYS)) {
} else {
executor.shutdownNow();
}
long endTime = System.currentTimeMillis();
System.out.println("\nParalle Execution Time : " + (endTime - startTime)
+ " milliseconds.");
}
}
