Question

I am running below code via eclipse in windows and then in Unix as standalone java.

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.sql.SQLException;
import java.text.ParseException;

public class readObjectBoeing {



/**
 * @param args
 * @throws ParseException 
 * @throws SQLException 
 */
public static void main(String[] args) {
    //File file = new File("/opt/app/d1ebp1m1/dv01/Vibhor/test/00017741_repository.dat");
    File file = new File("C:/_Vibhor/00017741_repository.dat");
    InputStream is;
    try {
        is = new FileInputStream(file);
        byte[] b = toByteArray(is);//read from file;
        Object o1 =null;
        o1 = convertByteArrayToObject(b);
    } catch (FileNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (Exception e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

}
public static Object convertByteArrayToObject(byte[] buf) throws Exception 
{

    if (buf.length == 0)
    {
        return null;
    }
    long startTime = -1;
    long step1=-1,step2=-1;
    Object                  obj = null;
    ByteArrayInputStream    bis = null;
    ObjectInputStream       in  = null;
    try 
    {   
        bis = new ByteArrayInputStream(buf);
        in  = new ObjectInputStream(bis);
        startTime = System.currentTimeMillis()/1000;
        obj = in.readObject();
        step1 = System.currentTimeMillis()/1000 - startTime ;
        System.out.println("in.readObject()!! :  " + step1);
    } 
    catch (Exception e) 
    {
        throw e;
    } 
    finally 
    {
        if (in != null) 
        {
            in.close();
        }
        if (bis != null) 
        {
            bis.close();
        }
        in  = null;
        bis = null;
    }

    return obj;
}
public static byte[] toByteArray(InputStream input) throws IOException
{
    ByteArrayOutputStream output = new ByteArrayOutputStream();
    long count = 0L;
    byte[] buffer =new byte[4096];
    for(int n = 0; -1 != (n = input.read(buffer));){
        output.write(buffer, 0, n);
        count += n;
    }
    return output.toByteArray();
}

}

00017741_repository.dat – it is 57Mb file.
In windows obj = in.readObject();– it takes me 4-5 seconds.
But in Unix obj = in.readObject(); it takes me 19 – 25 sec!

I am using VM args -Xmx512m to execute in both cases.

In unix:

java version "1.6.0_29"
Java(TM) SE Runtime Environment (build 1.6.0_29-b11)
Java HotSpot(TM) Server VM (build 20.4-b02, mixed mode)

In Windows:

jre 1.6.0_26

What am I missing here? Any suggestions to improve the performance in unix?

Answer 1

Here are two specific things you can do to figure this one out:

1. make sure that on Unix the file resides on a local file system and not on a network mount;
2. use a profiler (such as YourKit) to find out where the time is spent.