How can I force a Java program in Eclipse to use multiple processor cores?

Question

How can I force a Java program in Eclipse to use multiple processor cores?

I am doing a research project on how adding cores to a processor affects the speed of computing. I programmed my own test to do this in Java with the Eclipse platform. My problem is that when starting the program there are very few differences between the time it takes for the computer when it uses only 1 processor core, depending on how much time it takes when it uses all 6. Is there a way to get the program to use additional processor cores so that they work faster on 6 cores? Here is a copy of the code:

import java.util.Calendar;
import java.text.SimpleDateFormat;
import java.util.Scanner;
import java.text.*;
public class SciFair 
{
/**
     * N. Roberts
     * 1/13/11
     * Science Fair 2011
     */
public static String now(String dateFormat) {
   Calendar cal = Calendar.getInstance();
   SimpleDateFormat sdf = new SimpleDateFormat(dateFormat);
   return sdf.format(cal.getTime());

 }

    public static void main(String[] args) 
    {

        Scanner dataIn = new Scanner(System.in);
        DecimalFormat timeInSeconds = new DecimalFormat("##.###");

        System.out.println("Are you ready to begin the benchmark? ");
        String response = dataIn.nextLine();
        double num = 5832544225416546445465465465465465448412168546725.2655236355335649499923164684654345649874181221173246189579162421579584572121334216957951462175918894199993642446445548521652158975;
        double endNum = 0;

        if(response.equals("Yes") || response.equals("yes") || response.equals("Ok") || response.equals("ok"))
        {

         System.out.println("Benchmark starting at " + SciFair.now("H:mm:ss:SSS") + ".");

         String startTimeHours = SciFair.now("H");
         String startTimeMinutes = SciFair.now("mm");
         String startTimeSeconds = SciFair.now("ss");
         String startTimeMilliseconds = SciFair.now("SSS");
         double startTimeHoursNumFormat = Double.valueOf(startTimeHours.trim()).doubleValue();
         double startTimeMinutesNumFormat = Double.valueOf(startTimeMinutes.trim()).doubleValue();
         double startTimeSecondsNumFormat = Double.valueOf(startTimeSeconds.trim()).doubleValue();
         double startTimeMillisecondsNumFormat = Double.valueOf(startTimeMilliseconds.trim()).doubleValue();
         double startHoursInSeconds = (startTimeHoursNumFormat * 3600);
         double startMinutesInSeconds = (startTimeMinutesNumFormat * 60);
         double startMillisecondsInSeconds = (startTimeMillisecondsNumFormat / 1000);
         double startTotalSeconds = (startHoursInSeconds + startMinutesInSeconds + startTimeSecondsNumFormat + startMillisecondsInSeconds);

            for(double numberRun = 0; numberRun <= 1000000000; numberRun++)
            {
                endNum = endNum+((num * 58445246411658545558.458561435435385465146445641894984984651321616548946132131654984 + 26564.6351648941654984156 / 321654984616321654654984365.3216548974165416484 + 216541648165141654.23164584961321316546844651 * 65616484316541486541.1654484646546576746862468546576248645814668585145181 / 111.3216516543464545795479884754424759845 * 3467247954975472171276545789595.4721756147541715715157145715145714514748717521 / 31654688498445132154.3215449848489461531654 * 61654984132165465484464131321145644684.3164846434654648446546546465456465465414321165118547521569845258547566352544 / 32136546465434654654484843131.3164484151515121211554464547951126758178571454164175415417584175664) / 2431276251975915431326725157958456157321624621765419.4321672175951247316726451751487465462645754579517232172757497516373127651975167516715);    
            }
            System.out.println("\nBenchmark is 10% complete.");
            for(double numberRun = 0; numberRun <= 1000000000; numberRun++)
            {
                endNum = endNum+((num * 58445246411658545558.458561435435385465146445641894984984651321616548946132131654984 + 26564.6351648941654984156 / 321654984616321654654984365.3216548974165416484 + 216541648165141654.23164584961321316546844651 * 65616484316541486541.1654484646546576746862468546576248645814668585145181 / 111.3216516543464545795479884754424759845 * 3467247954975472171276545789595.4721756147541715715157145715145714514748717521 / 31654688498445132154.3215449848489461531654 * 61654984132165465484464131321145644684.3164846434654648446546546465456465465414321165118547521569845258547566352544 / 32136546465434654654484843131.3164484151515121211554464547951126758178571454164175415417584175664) / 2431276251975915431326725157958456157321624621765419.4321672175951247316726451751487465462645754579517232172757497516373127651975167516715);    
            }
            System.out.println("Benchmark is 20% complete..");
            for(double numberRun = 0; numberRun <= 1000000000; numberRun++)
            {
                endNum = endNum+((num * 58445246411658545558.458561435435385465146445641894984984651321616548946132131654984 + 26564.6351648941654984156 / 321654984616321654654984365.3216548974165416484 + 216541648165141654.23164584961321316546844651 * 65616484316541486541.1654484646546576746862468546576248645814668585145181 / 111.3216516543464545795479884754424759845 * 3467247954975472171276545789595.4721756147541715715157145715145714514748717521 / 31654688498445132154.3215449848489461531654 * 61654984132165465484464131321145644684.3164846434654648446546546465456465465414321165118547521569845258547566352544 / 32136546465434654654484843131.3164484151515121211554464547951126758178571454164175415417584175664) / 2431276251975915431326725157958456157321624621765419.4321672175951247316726451751487465462645754579517232172757497516373127651975167516715);    
            }
            System.out.println("Benchmark is 30% complete...");
            for(double numberRun = 0; numberRun <= 1000000000; numberRun++)
            {
                endNum = endNum+((num * 58445246411658545558.458561435435385465146445641894984984651321616548946132131654984 + 26564.6351648941654984156 / 321654984616321654654984365.3216548974165416484 + 216541648165141654.23164584961321316546844651 * 65616484316541486541.1654484646546576746862468546576248645814668585145181 / 111.3216516543464545795479884754424759845 * 3467247954975472171276545789595.4721756147541715715157145715145714514748717521 / 31654688498445132154.3215449848489461531654 * 61654984132165465484464131321145644684.3164846434654648446546546465456465465414321165118547521569845258547566352544 / 32136546465434654654484843131.3164484151515121211554464547951126758178571454164175415417584175664) / 2431276251975915431326725157958456157321624621765419.4321672175951247316726451751487465462645754579517232172757497516373127651975167516715);    
            }
            System.out.println("Benchmark is 40% complete....");
            for(double numberRun = 0; numberRun <= 1000000000; numberRun++)
            {
                endNum = endNum+((num * 58445246411658545558.458561435435385465146445641894984984651321616548946132131654984 + 26564.6351648941654984156 / 321654984616321654654984365.3216548974165416484 + 216541648165141654.23164584961321316546844651 * 65616484316541486541.1654484646546576746862468546576248645814668585145181 / 111.3216516543464545795479884754424759845 * 3467247954975472171276545789595.4721756147541715715157145715145714514748717521 / 31654688498445132154.3215449848489461531654 * 61654984132165465484464131321145644684.3164846434654648446546546465456465465414321165118547521569845258547566352544 / 32136546465434654654484843131.3164484151515121211554464547951126758178571454164175415417584175664) / 2431276251975915431326725157958456157321624621765419.4321672175951247316726451751487465462645754579517232172757497516373127651975167516715);    
            }
            System.out.println("Benchmark is 50% complete.....");
            for(double numberRun = 0; numberRun <= 1000000000; numberRun++)
            {
                endNum = endNum+((num * 58445246411658545558.458561435435385465146445641894984984651321616548946132131654984 + 26564.6351648941654984156 / 321654984616321654654984365.3216548974165416484 + 216541648165141654.23164584961321316546844651 * 65616484316541486541.1654484646546576746862468546576248645814668585145181 / 111.3216516543464545795479884754424759845 * 3467247954975472171276545789595.4721756147541715715157145715145714514748717521 / 31654688498445132154.3215449848489461531654 * 61654984132165465484464131321145644684.3164846434654648446546546465456465465414321165118547521569845258547566352544 / 32136546465434654654484843131.3164484151515121211554464547951126758178571454164175415417584175664) / 2431276251975915431326725157958456157321624621765419.4321672175951247316726451751487465462645754579517232172757497516373127651975167516715);    
            }
            System.out.println("Benchmark is 60% complete......");
            for(double numberRun = 0; numberRun <= 1000000000; numberRun++)
            {
                endNum = endNum+((num * 58445246411658545558.458561435435385465146445641894984984651321616548946132131654984 + 26564.6351648941654984156 / 321654984616321654654984365.3216548974165416484 + 216541648165141654.23164584961321316546844651 * 65616484316541486541.1654484646546576746862468546576248645814668585145181 / 111.3216516543464545795479884754424759845 * 3467247954975472171276545789595.4721756147541715715157145715145714514748717521 / 31654688498445132154.3215449848489461531654 * 61654984132165465484464131321145644684.3164846434654648446546546465456465465414321165118547521569845258547566352544 / 32136546465434654654484843131.3164484151515121211554464547951126758178571454164175415417584175664) / 2431276251975915431326725157958456157321624621765419.4321672175951247316726451751487465462645754579517232172757497516373127651975167516715);    
            }
            System.out.println("Benchmark is 70% complete.......");
            for(double numberRun = 0; numberRun <= 1000000000; numberRun++)
            {
                endNum = endNum+((num * 58445246411658545558.458561435435385465146445641894984984651321616548946132131654984 + 26564.6351648941654984156 / 321654984616321654654984365.3216548974165416484 + 216541648165141654.23164584961321316546844651 * 65616484316541486541.1654484646546576746862468546576248645814668585145181 / 111.3216516543464545795479884754424759845 * 3467247954975472171276545789595.4721756147541715715157145715145714514748717521 / 31654688498445132154.3215449848489461531654 * 61654984132165465484464131321145644684.3164846434654648446546546465456465465414321165118547521569845258547566352544 / 32136546465434654654484843131.3164484151515121211554464547951126758178571454164175415417584175664) / 2431276251975915431326725157958456157321624621765419.4321672175951247316726451751487465462645754579517232172757497516373127651975167516715);    
            }
            System.out.println("Benchmark is 80% complete........");
            for(double numberRun = 0; numberRun <= 1000000000; numberRun++)
            {
                endNum = endNum+((num * 58445246411658545558.458561435435385465146445641894984984651321616548946132131654984 + 26564.6351648941654984156 / 321654984616321654654984365.3216548974165416484 + 216541648165141654.23164584961321316546844651 * 65616484316541486541.1654484646546576746862468546576248645814668585145181 / 111.3216516543464545795479884754424759845 * 3467247954975472171276545789595.4721756147541715715157145715145714514748717521 / 31654688498445132154.3215449848489461531654 * 61654984132165465484464131321145644684.3164846434654648446546546465456465465414321165118547521569845258547566352544 / 32136546465434654654484843131.3164484151515121211554464547951126758178571454164175415417584175664) / 2431276251975915431326725157958456157321624621765419.4321672175951247316726451751487465462645754579517232172757497516373127651975167516715);    
            }
            System.out.println("Benchmark is 90% complete.........");
            for(double numberRun = 0; numberRun <= 1000000000; numberRun++)
            {
                endNum = endNum+((num * 58445246411658545558.458561435435385465146445641894984984651321616548946132131654984 + 26564.6351648941654984156 / 321654984616321654654984365.3216548974165416484 + 216541648165141654.23164584961321316546844651 * 65616484316541486541.1654484646546576746862468546576248645814668585145181 / 111.3216516543464545795479884754424759845 * 3467247954975472171276545789595.4721756147541715715157145715145714514748717521 / 31654688498445132154.3215449848489461531654 * 61654984132165465484464131321145644684.3164846434654648446546546465456465465414321165118547521569845258547566352544 / 32136546465434654654484843131.3164484151515121211554464547951126758178571454164175415417584175664) / 2431276251975915431326725157958456157321624621765419.4321672175951247316726451751487465462645754579517232172757497516373127651975167516715);    
            }

            String endTimeHours = SciFair.now("H");
         String endTimeMinutes = SciFair.now("mm");
         String endTimeSeconds = SciFair.now("ss");
         String endTimeMilliseconds = SciFair.now("SSS");
         double endTimeHoursNumFormat = Double.valueOf(endTimeHours.trim()).doubleValue();
         double endTimeMinutesNumFormat = Double.valueOf(endTimeMinutes.trim()).doubleValue();
         double endTimeSecondsNumFormat = Double.valueOf(endTimeSeconds.trim()).doubleValue();
         double endTimeMillisecondsNumFormat = Double.valueOf(endTimeMilliseconds.trim()).doubleValue();
         double endHoursInSeconds = (endTimeHoursNumFormat * 3600);
         double endMinutesInSeconds = (endTimeMinutesNumFormat * 60);
         double endMillisecondsInSeconds = (endTimeMillisecondsNumFormat / 1000);
         double endTotalSeconds = (endHoursInSeconds + endMinutesInSeconds + endTimeSecondsNumFormat + endMillisecondsInSeconds);

         double elapsedTime = (endTotalSeconds - startTotalSeconds);

         System.out.println("\nThe benchmark is complete at " + SciFair.now("H:mm:ss:SSS") + ", and the end result is " + endNum + ".");
         System.out.println("\nThe benchmark was run in " + timeInSeconds.format(elapsedTime) + " seconds.");
        }

        else
        {
            System.out.println("\nPlease restart the program when you are ready to benchmark.");
        }
    }
}

+3

java eclipse benchmarking

Numa robertson Jan 19 '11 at 16:27

source share

7 answers

Daniel · Answer 1 · 2011-01-19T16:28:35+0000

. JVM.

: . : Concurrency Java Tutorial. , .

Jerry Andrews · Answer 2 · 2011-01-19T16:38:08+0000

Java :

, :

   setUpTimers();
   long numberOfLoops=10000L;
   doSomethingThatTakesALongTime(numberOfLoops);
   reportTimers();

:

   setUpTimers();
   List<Thread> threads = new ArrayList<Thread>();
   long numberOfLoops=10000L;
   for (int i=0; i<numberOfThreads; ++i) {
      Thread t = new Thread() {
         public void run() {
            doSomethingThatTakesALongTime(numberOfLoops/numberOfThreads);
         }
      };
      t.start();
      threads.add(t);
   }
   for (Thread t : threads){
      t.join();
   }
   reportTimers();

, , , " " " ".

jjnguy · Answer 3 · 2011-01-19T16:33:39+0000

, , . , .

, for-loop . .

, :

Thread thread1 = new Thread(){public void run(){
// your for-loop
}};

for, thread1.start(); .

thread1.join() Thread, .

:

Create all threads;
Start all threads;
Wait for all threads to complete;
Report on time taken to complete all threads;

.

Mark Peters · Answer 4 · 2011-01-19T16:41:47+0000

: . :

 long start = System.currentTimeMillis();

 //do work

 long end = System.currentTimeMillis();
 double elapsedSeconds = (end - start) / 1000.0;

now(), .

berry120 · Answer 5 · 2011-01-19T16:30:22+0000

, java.util.concurrent. !

Brian Beckett · Answer 6 · 2011-01-19T16:39:15+0000

Java concurrency .

, , . , - , , .

jzd · Answer 7 · 2011-01-19T16:39:41+0000

:
10 . , .
System.currentTimeMillis() SimpleDateFormat .
Use equalsIgnoreCase when testing your input instead of testing multiple lines. (What if the user enters "oK"?)

How can I force a Java program in Eclipse to use multiple processor cores?

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