使用linux-redhat的java上的内存不足

我的linux机器配置是15Gb RAM.

import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URL;
import java.sql.ResultSet;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;

/**
 *
 * @author ndoshi
 */
public class Dwnld {

    BufferedImage bi8 = null,bi16 = null;
    ImageIcon ii = null;
    ResultSet rs,rsDwnld;
    String OG = "ogImage";
    String CROP8 = "Crop8";
    String CROP16 = "Crop16";
    String TIME = "",ErrorLog = "",ErrorLogPro = "";
    int hashInc8 = 0;
    int hashInc16 = 0;
    int totalround = 0;
    int countProcess = 0;
    boolean download_new = false;
    private int row = 0;
    int Dwnld = 0,NotDwnld = 0;
    final String OP_Log = "Log",OP_Error = "ErrorLog",OP_ErrorPro = "ErrorLogProcess";

    int r,g,b,k,ih,j;
    int sr = 0,sg = 0,sb = 0,sk = 0;
    int rg,gg,bg,kg;
    String s = "",s1 = "",hash16,hash8;

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        new Dwnld();
    }

    public Dwnld(){
    try {
            BufferedImage image = null;
            InputStream is = null;
            OutputStream os = null;
            URL url = new URL("https://rukminim1.flixcart.com/image/312/312/t-shirt/u/g/k/33solidblackmelangeblack-sayitloud-m-original-imaehfytzzzazfyf.jpeg?q=70");
            is = url.openStream();
            os = new FileOutputStream(OG + "1.jpg");
            byte[] b = new byte[2048];
            int length;
            while ((length = is.read(b)) != -1) {
                os.write(b,length);
            }
            image = ImageIO.read(new File(OG + "1.jpg"));
            is.close();
            os.close();
            System.out.println("Hash 16 = "+hash16);
            System.out.println("Hash 8 = "+hash8);
        } catch (Exception ex) {
            System.out.println(ex.getMessage());
        }

    }

}

我正在运行sam eby通过XMS和&增加内存. XMX为

java -Xms2048m -Xmx6096m Dwnld

得到错误：

Exception in thread "main" java.lang.OutOfMemoryError: unable to create new native thread
        at java.lang.Thread.start0(Native Method)
        at java.lang.Thread.start(Thread.java:714)
        at sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:1056)
        at sun.security.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1332)
        at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1359)
        at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1343)
        at sun.net.www.protocol.https.HttpsClient.afterConnect(HttpsClient.java:563)
        at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(AbstractDelegateHttpsURLConnection.java:185)
        at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1301)
        at sun.net.www.protocol.https.HttpsURLConnectionImpl.getInputStream(HttpsURLConnectionImpl.java:254)
        at java.net.URL.openStream(URL.java:1037)
        at Dwnld.<init>(Dwnld.java:53)
        at Dwnld.main(Dwnld.java:43)