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how to increase jvm heap size in jdk1.5.0  RSS feed

durgaprasad ganji
Posts: 7
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Hi all,

I am getting java.lang.OutOfMemoryError: Java heap space Exception ,

when running below java class in eclipse editor by configuring JVM of JDK1.5.0 within eclipse (or at command prompt) on windows platform

by using below class I am merging two Index Directories(one is 1.87 GB of size and other one is 522 MB of size) into new one using Lucene API
import java.io.File;
import org.apache.lucene.analysis.standard.StandardAnalyzer;
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.FSDirectory;
import org.apache.lucene.store.RAMDirectory;
public class MergeIndex {

private MergeIndex (){

public static void main(String arg[]) throws InvalidDocDBXMLFormatException {


}catch(Exception e){


public static void mergeIndexes() {

try {
System.out.println("before add indexwriter");
IndexWriter writerDisk = new IndexWriter(FSDirectory.getDirectory(new File("D:\\DocServerData\\MergedIndexes\\DocDB1_Category1_Index"), true),new StandardAnalyzer(),true);
long l1 = System.currentTimeMillis();
System.out.println("before addIndexes method>>>>"+l1);
writerDisk.addIndexes(new Directory[]{FSDirectory.getDirectory(new File("E:\\1lac-7mar\\DocDB1_Category1_Index"), false),FSDirectory.getDirectory(new File("E:\\2lacs-19feb\\DocDB1_Category1_Index"), false)}) ;
long l2 = System.currentTimeMillis();
System.out.println("before Optimize method>>>"+ (l2-l1));
System.out.println("after Optimize method"+System.currentTimeMillis());
System.out.println("after add indexwriter");
}catch(Exception e){
System.out.println("Exception Occured>>>>>>" +e);


below is snapshot of my java class

Call tree (all threads together)
Name Time (ms)
All Threads
831,735 100 %
MergeIndex .main(String[])
831,563 100 %
171 0 %

Generated by YourKit Java Profiler 6.0.12 Mar 9, 2007 10:34:49 AM

It would be appreacited if any body tell me how to increase JAva heap size
in jvm on windows paltform
Wiyanto Ngasinur
Ranch Hand
Posts: 34
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run your java class with command line :
java -Xmx1G [class]

this code set maximum heap 1 Giga
Deepak Bala
Posts: 6663
Firefox Browser Linux MyEclipse IDE
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Again. Not SCJP
Jesper de Jong
Java Cowboy
Posts: 16057
Android IntelliJ IDE Java Scala Spring
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You already asked the same question, have a look at the answers there.
It is sorta covered in the JavaRanch Style Guide.
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