Techie musings

A very wonderful session about future of the WEB. Rapid growth and very great to see WEB having most of the native capabilities. You can find the slides here. Can't wait to play with these things!!

I wonder in this fast pace browser war, why not browsers provide native cross tab communication something like

window.getMyDomainBrowserTabs() -> returns array of windows

Once we get the array of window objects of all browser tabs which hold webpages severed from my domain, Using HTML5 window.postMessage we can communicate with all the browser tabs using its respective window object.

Though we accomplish it using localStorage, cookie polling..etc but obviously native is more reliable.

Hope to see this kind of native support in future

Auto-saving CSS And JavaScript Changes Locally From The Chrome Developer Tools.
Pretty cool stuff, saves lot of development time.

Chrome DevTools AutoSave (HD) from Addy Osmani on Vimeo.

Very simple things but yields greater performance.

We are moving towards a world where desktop and web based applications merge. Where the term personal computer doesn't just mean desktops but also includes mobile devices. Where applications and data belong to the cloud and can move from one device to another.

IMO, the credit for merging desktop and web based applications goes to Google and the credit for creating the 'personal devices' market and providing a common way to access data and applications across these devices goes to Apple.

Here is the Chrome latest release where we can run c/c++ apps inside browser.

Very cool stuff!!!

I have spent enough time in finding memory leak detection tool and explored few tools such as sIEve, Drip, Software Verification Javascript memory observer, IEMemoryleakDetector....etc.

Unfortunately i could not find them helpful to me. After further investigation i realized that browser system process private bytes consumption is the best way to identify if the app is leaking memory or not.

I used processexplorer.exe to monitor private bytes of a process but here there is no option to record and play the memory consumption.

One of my earlier posts will be useful in recording private bytes of any windows system process.

I don't find any tool which can be used for recording windows system process memory and used for later review.

There are some tools like process explorer but these are live it won't allow us to record the memory graph. So i decided to write java client which will poll periodically using DOS command WMIC and get the private bytes of a system process.


Usage :-

Paste the below code and put in MemoryMonitor.java

javac MemoryMonitor.java
java MemoryMonitor process_name poll_interval test_duration file

java MemoryMonitor firefox.exe 5 60 d:\\test.csv

So ideally, test.csv contains private bytes data of all intervals later you can use this file for drawing graphs.


Cheers!!!!!!!!!!

Here is the program code:-


import java.awt.Toolkit;
import java.io.BufferedInputStream;
import java.io.BufferedWriter;
import java.io.ByteArrayOutputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStreamWriter;
import java.util.ArrayList;
import java.util.List;
import java.util.Timer;
import java.util.TimerTask;


//java MemoryMonitor firefox.exe 5 60 d:\\test.csv

public class MemoryMonitor {

public String PROCESS_NAME = "eclipse.exe";
public int TIME_INTERVAL = 5; // in seconds
public int TOTAL_TEST_TIME = 60; // in seconds
public String DESTINATION_FLE = "d:\\memory_usage.csv";

Toolkit toolkit;

Timer timer;
Timer timer1;
List memoryList;

public MemoryMonitor(String args[]){
PROCESS_NAME = args[0] ; TIME_INTERVAL = Integer.parseInt(args[1]) ; TOTAL_TEST_TIME = Integer.parseInt(args[2]) ; DESTINATION_FLE = args[3];
memoryList = new ArrayList();
toolkit = Toolkit.getDefaultToolkit();
timer = new Timer();
timer1 = new Timer();
timer1.schedule(new ExitTimerTask(), TOTAL_TEST_TIME * 1000);
scheduleTimer();
}

public void scheduleTimer(){
getMemoryDetails();
timer.schedule(new MemoryDetailsTask(), TIME_INTERVAL * 1000);
}

public void getMemoryDetails(){
try {
Process proc = Runtime.getRuntime().exec("WMIC PROCESS where Caption=\""+PROCESS_NAME+"\" get PageFileUsage");
InputStream procOutput = proc.getInputStream();
String value = readInputStreamAsString(procOutput);
String array[] = value.split("\n");
double privateBytesValue = 0;
for(int i = 1 ; i < array.length ; i++){
if(array[i].trim().length()>0){
String privateBytes = array[i].substring(0, array[i].indexOf(" "));
privateBytesValue+= Double.parseDouble(privateBytes) / 1024;
}
}
System.out.println(privateBytesValue);
memoryList.add(privateBytesValue);
} catch (Exception e) {
System.out.println("Error occured");
e.printStackTrace();
System.exit(0);
}
}

public String join(List list, String conjunction)
{
StringBuilder sb = new StringBuilder();
boolean first = true;
for (Object item : list)
{
if (first)
first = false;
else
sb.append(conjunction);
sb.append(item);
}
return sb.toString();
}

public String readInputStreamAsString(InputStream in) throws IOException {

BufferedInputStream bis = new BufferedInputStream(in);
ByteArrayOutputStream buf = new ByteArrayOutputStream();
int result = bis.read();
while (result != -1) {
byte b = (byte)result;
buf.write(b);
result = bis.read();
}
return buf.toString();
}

class MemoryDetailsTask extends TimerTask {
public void run() {
getMemoryDetails();
scheduleTimer();
}
}

class ExitTimerTask extends TimerTask {
public void run() {
try {
BufferedWriter out = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(DESTINATION_FLE),"UTF8"));
out.write(join(memoryList,","));
out.close();
System.out.println("Please find this file for the report "+DESTINATION_FLE);
} catch (Exception e) {
// TODO Auto-generated catch block
System.out.println("Not able to write to the file "+DESTINATION_FLE);
e.printStackTrace();
};
System.exit(0);
}
}

public static void main(String args[]) {
new MemoryMonitor(args);
}

}

In javascript, We can write programs in very optimized manner as we can send functions as arguments or as return values. Here is a small snippet of code where we can avoid repeat work.

function addHandler(elem, event, handler){
if(elem.addEventListener){ // DOM2
addHandler = function(elem, event, handler){
elem.addEventListener(event, handler, false);
}
}else{ // IE
addHandler = function(elem, event, handler){
elem.attachEvent("on" + event, handler);
}
}

addHandler(elem, event, handler);

During addHandler fist call the function definition varied.

I hope you will really enjoy following video and will get to know new way of javascript coding from Jquery source.

Paul Irish : 10 Things I Learned from the jQuery Source from yayQuery on Vimeo.

Generally we might need to modify the structure and behaviour of a program at runtime
(or )
we have to call a method of a class but we will get class name and method at runtime only. I mean during compile time we dont know what to use.

In these type of scnerios we can opt for reflection style of programming. I will show you sample program how to use in different languages.

Java:-
// No Reflection
new Foo().hello();
// After Reflection
Class cls = Class.forName("Foo");
cls.getMethod("hello", null).invoke(cls.newInstance(), null);

Javascript:-
// No Reflection
new Foo().hello()
// After Reflection
new (eval('Foo'))()['hello']()

Python:-
# No Reflection
Foo().hello()
# After Reflection
getattr(globals()['Foo'](), 'hello')()

Javascript memory leaks especially in IE during removal of any DOM element (or) setting innnerHTML property. During those actions we should explicitly set "null" to their event handler's property. Have a look at "purge" function in the following link.

Source:- http://javascript.crockford.com/memory/leak.html

In my last post i wrote about HTML5 websocket. As i dig into it i found jwebsocket.

Here is my observation:-

Pros:-

1) jWebSocket is a pure Java/JavaScript high speed bidirectional communication solution for the Web - secure, reliable and fast.
2) Make use of websockets if the browser does not support this then it will fallback to flashbridge.
3) Standalone jwebsocket server is provided. You can even add jwebsocket capabilities to existing web servers like jetty,tomcat..etc.
4) Client side plug-in is available so that you can think about only on application logic.
5) Can be used in different ways like Chat, Steaming, RPC, Shared object, Shared canvas. Lot of demos are there in the site.

Cons:-

1) What if flash crashed because of some other application in the browser.
2) Could have provided long polling too as another fallback option.
3) Need to support SSL for all browsers.
4) Could have provided some tool to perform load/stress tests. Since it is not http communication we can not perform load tests using Jmeter..etc.

Finally it is pretty awesome and very good. I am exploring it. If anyone of you using it please let me know about its performance.