Databases
StackOverflow2013
Postsdbo
POMulti thread array sort Java
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POMulti thread array sort Java
    primarykey
    data
    text
    <p>So hello!</p> <p>I'm trying to sort int array with several threads. Now I've got something like this:</p> <pre><code>import java.util.Arrays; public class MultiTread extends Thread{ int sizeOfArray; public static int treadsN = 4; public static int sortFrom; public static int sortTo; public MultiTread(int sizeOfArray, int treadsN) { this.sizeOfArray = sizeOfArray; this.treadsN = treadsN; } public MultiTread(int[] arrayToSort, int sizeOfArray) { this.sizeOfArray = sizeOfArray; } public static int [] creatingArray(int sizeOfArray) { int [] arrayToSort = new int[sizeOfArray]; int arrayLength = arrayToSort.length; for (int counter = 0; counter&lt;arrayLength; counter++){ arrayToSort[counter] = (int)(8000000*Math.random()); } return arrayToSort; } public static int [] sortInSeveralTreads(final int [] arrayToSort){ int [] newArr = new int[arrayToSort.length]; int numberOfThreads = treadsN; if (numberOfThreads == 0){ System.out.println("Incorrect value"); return arrayToSort; } if (numberOfThreads == 1){ Arrays.sort(arrayToSort); System.out.println("Array sorted in 1 thread"); } else { final int lengthOfSmallArray = arrayToSort.length/numberOfThreads; sortFrom = 0; sortTo = lengthOfSmallArray; for (int progress = 0; progress &lt; numberOfThreads; progress++){ final int [] tempArr = Arrays.copyOfRange(arrayToSort,sortFrom,sortTo); new Thread(){public void run() { Arrays.sort(tempArr); }}.start(); sortFrom = sortTo; sortTo += lengthOfSmallArray; newArr = mergeSort(newArr, tempArr); } new Thread(){public void run() { Arrays.sort(Arrays.copyOfRange(arrayToSort, arrayToSort.length-lengthOfSmallArray, arrayToSort.length)); }}.start(); newArr = mergeSort(newArr, arrayToSort); } return newArr; } public static int [] mergeSort(int [] arrayFirst, int [] arraySecond){ int [] outputArray = new int[arrayFirst.length+arraySecond.length]; while (arrayFirst.length != 0 &amp;&amp; arraySecond.length != 0){ int counter = 0; if (arrayFirst[0] &lt; arraySecond[0]){ outputArray[counter] = arrayFirst[0]; counter++; arrayFirst = Arrays.copyOfRange(arrayFirst, 1, arrayFirst.length); }else { outputArray[counter] = arraySecond[0]; counter++; arraySecond = Arrays.copyOfRange(arraySecond, 1, arraySecond.length); } } return outputArray; } public static void main(String[] args){ long startTime; long endTime; int [] a = creatingArray(8000000); startTime = System.currentTimeMillis(); a = sortInSeveralTreads(a); endTime = System.currentTimeMillis(); System.out.println(Thread.activeCount()); System.out.printf("Sorted by: %d treads in %.7f seconds %n", treadsN, (float)(endTime-startTime)*1e-6); try { Thread.currentThread().sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } System.out.println(Thread.activeCount()); } } </code></pre> <p>I know that it's not very good realization. All works fine but merge sort works too bad - it crashes... Error should be in that lines:</p> <pre><code>Exception in thread "main" java.lang.OutOfMemoryError: Java heap space at java.util.Arrays.copyOfRange(Arrays.java:3137) at MultiTread.mergeSort(MultiTread.java:78) at MultiTread.sortInSeveralTreads(MultiTread.java:61) at MultiTread.main(MultiTread.java:94) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at com.intellij.rt.execution.application.AppMain.main(AppMain.java:120) </code></pre> <p>What i'm doing wrong?</p>
    singulars
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. This table or related slice is empty.
    1. USIvan Kozlov
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    2. PO
      singulars
      1. PTAnswer
    3. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POMulti thread array sort Java
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. POMulti thread array sort Java
      1. This table or related slice is empty.
      1. VTDownMod
    1. COYou are trying to create a array with 8 million elements and you have a OOM error -- you are using too much memory, which is larger than your JVM's heap memory setting. Can you point out exactly what the 78th, 61st and 94th line in MultiTread.java is?
      singulars
      1. POMulti thread array sort Java
      1. UScoolcfan
    2. COint [] outputArray = new int[arrayFirst.length+arraySecond.length];
      singulars
      1. POMulti thread array sort Java
      1. USIvan Kozlov
    3. COa = sortInSeveralTreads(a);
      singulars
      1. POMulti thread array sort Java
      1. USIvan Kozlov
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload