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gwt application stopped running suddenly

first of all I am sorry on my English.
I have a problem in my Gwt application.
I build Gwt application and I work on application every day
Yesterday I want to still work on my application but is stopped worked and i do not know why and I not get errors
The application compiled and I get the Url to run on browser
I copy the Url to my Firefox browser and not happened nothing.
I put break point in my entry point class and I see the application not arrived to entry point and I do not know why.
I try to open new project to check maybe the problem in eclipse or in Gwt plug in but the new project worked excellent so I understand the problem in specific this project.
I need help
thank you everyone

Okay i have 3 possible suspicions:
You updated your Application, but for some reason some JavaScript stayed inside the Firefox cache. Solution: Go to options and "Clean cache" and always try to press CTRL+F5 instead of just reloading, this will clean the current website's cache saved in your Browser.
Your HDD is full(less likely). You said you work everyday on the app. The caching in dev-mode is very VERY bad(for me it once contained 300GB of cached data). there is a folder called <win_user>/AppData/Local/Temp - delete everything inside if you find a lot of "gwt-<something>" files and check the folder's size. There is nothing valuable inside it(if you didn't place anything inside :D)
P.S. Turns out it was a Firefox Memory-leak that has been fixed in GWT 2.6.0 :)
Your Eclipse messed up some random stuff. As always - Project > Clean...
Then right click on app and let gwt recomile your app(if you have an ant file that uses the gwt-compiler, execute that)
I can't really think of anything else...
The only thing that could be is that YOU changed something, but you said you didn't so...
Hopefully it works,
Laurenz

Performance measuring

I wanted to know if there is a way to measure the overhead of a specific function or even the running time of an application in Eclipse (with the capability to run the test for arbitrary times to get the average time).
I have a code that should be executed in Eclipse therefore looking for such a thing. I know that we have Jmeter in Netbeans and I'm looking for something similar in Eclipse.
Thanks

I have had good experiences with JProfiler. It should be precise enough to give usable data even when you run your function only once, depending on how you set it up. It also optionally integrates with Eclipse.
It's not free, but there's a fully functioning trial available.

I used Traceview before and it worked quite good to me.
It quite easy to use, just open the DDMS view in eclipse and look for the icon with three arrows with a red dot (Start Method Profiling). Click the icon and test your app as you want. When you are done click on stop. The trace should open in a new tab.

You could use the following
http://www.jvmmonitor.org/
It's called Java Monitor and comes as an eclipse plugin. You can install it from eclipse market place.

Refreshing Swing application with Eclipse/MyEclipse

Say that we are writing a Java Swing application and we use Eclipse or MyEclipse to develop it. In web applications, you make code changes, you save and your ant deployment file takes care of the deployment of the changed files. Then you just refresh or hard refresh the web page and the changes appear there. Can we do the same thing for a Swing applications so that we don't have to close and open the program from the beginning every time we make a change?

I don't think so because you need hot code replacement ! Maybee using another framework.

You can't simply do that because once JVM is started, it loads the class files once and will not reload it untill next loading request. But you can use ClassLoader to load modified class files dynamically.
The following two articles may help:
IBM article on "hot class swap"
"Who Said Runtime Class Reloading Is Hard in Java?"
The first one is in Chinese, but you can look at the code and the result. I think the second article is more helpful for a GUI application.

In MyEclipse you can start your application in debug mode instead of run mode and changes you make will be pushed to the target VM; if changes you make cannot be replaced you'll see a dialog informing you the replace failed and you will need to restart your application. You don't need to place any breakpoints in the application, just starting in debug mode is sufficient.
As Guillaume states above, changes to the class structure will typically not be hot-synched, but changes within existing methods should be fine.
Obviously, how successfully hot-synched changes affect your running application would depend on your application design.

deployment time of "ear" annoying using jboss,ant, jsp's and prehistoric pc

I am developing a web based java app, running on jboss and sql server.
I seem to find myself spending an inordinate amount of time recompiling/deploying just to tweak the interface in jquery/javascript/css/html.
Any tips for reducing the turnaround ?
Its deployed to an ear file, so I can not alter the jsps/javascript after deployment(?). Yes, I have created the a static version of the webpage frontends but they do not give me the full functionality - none of the data from db/jstl processing.
To clarify its not so much the actual compile time itself (30seconds) as the ant builds are set-uo well and are very modular; its the subsequent deployment to jboss and accessing the application that cause the real headache.

If you do not work directly in an exploded war inside the hotdeploy folder of JBoss, then strongly consider it.

when developing with application server i've used this product in the past: JRebel from zeroturnaround.
It will prevent having to restart and redeploy an application running within an application server. It works for most scenario's however i found that there were a few occasions when a server restart were required(in my case making changes to the application initialisation). But if you're only working on the interface this product will save you a great number of deployments and restarts.
I have not used Jrebel in combination with JBoss but they mention it as a supported container so thta shouldn't be a problem.

I am an average web designer (at best!) and writing complicated HTML and CSS is a pain for me. A lot of what I do with styles and layout is trial and error and involves a lot of tweaking. I also change my mind frequently about exactly what shade of color I want things. Basically, I'm in the same boat as you.
Long ago I abandoned the idea of the tweak-deploy-test iteration cycle (mvn clean tomcat:deploy takes 2 minutes on my current project) as by the 10th iteration trying to sort a simple layout problem and waiting for the deployment would drive me round the bend. I now use two strategies;
Get a static copy of the HTML I want to work with. This usually means deploying the app, navigating to the page and saving it to a work directory somewhere. This saves the static HTML as well as any images. Next I copy the CSS files from my workspace into the work directory and hand edit the saved HTML file to point to these CSS files.
Open the static HTML page in Firefox. Now I can tweak the CSS or HTML and simply refresh Firefox to show the changes. Iteration time is now down to about 1 second. I can further improve my tweaking using the Firebug addon. This allows you to manipulate the CSS and HTML from within Firefox. This is especially useful for getting margin and padding size right. Once I've tweaked it in Firebug I hand edit the saved HTML and CSS then refresh Firefox to make sure I'm happy with the result.
At certain key stages I then make the changes to my workspace to reflect my tweaking on the static files. I then redeploy and test to make sure I got it right. As I use Firefox for all my development I have to pay special attention to browser compatibility, especially with IE, but this usually comes at a later stage.
Edit:
I didn't mention Javascript, but this process works great for JS too!

Why does GWT sometimes successfully compile and other times just stall?

I am working on a demo for a client of what's possible with GWT-Ext for GWT. After browsing for the simplest way to get up and running, I decided on installing the Google Plugin for Eclipse and using the New Web Application Wizard.
First time around, I followed these steps for create the default application:
Selected File > New > Web Application Project from the Eclipse menu.
In the New Web Application Project wizard, entered a name for the project (ExtDemo) and a java package name, com.extdemo.
Unchecked the "Use Google App Engine" check box.
Clicked Finish.
Right clicked it in package explorer and selected Run As > Run Configurations
Put a check in the Automatically Select Unused Port checkbox.
Clicked Run to see the default GWT 1.7 application
This worked fine... it launched GWT's hosted browser and the app worked as supposed to.
(I then continued to import GWT-Ext and add all sorts of widgets building up a nice little demo app)
However at some point when relaunching the app in hosted mode, the hosted browser displays an empty iframe. I even reverted the code to a point where everything was working as supposed to and... same thing, an empty iframe with the surrounding static content.
Now what is really strange is when I go through the process of creating the default application again by following the steps above, the hosted browser launches with an empty iframe again.
However when I click on Compile/Browse, this sometimes allows the app to launch in Firefox.
Anyone have this happen to them?

I have seen some odd behaviors occasionally. Here are some basic suggestions (some are dumb and you might have tried them already):
Use a new workspace
I do not know if GWT plugin somehow caches stuff in the embedded Jetty. If you are re-creating the default app/project, try and use a different name for the project.
Try and re-use a fixed port so that there is no possibility of having multiple servers running.
Update: Found a new "classic" solution:
Delete the cache in IE and possibly Firefox too. Apparently the 'script' tag content tends to be cached by IE. If this works, we can all try tearing our hair out!
Found the updated answer at this link:

I have had the same problem in the past and found it is much more likely to happen if limited CPU is available. For example if my older laptop was running on battery and had stepped down the CPU speed to save power it frequently happened. When running on mains in max performance mode it only happened occasionally. Now I have a much newer and more powerful laptop and the problem has gone away.
Another cause I found was too many breakpoints set up in eclipse and removing breakpoints would often clear the problem.

I've had issues with the browser caching.
Try clearing your browser cache, refresh a few times after a failed load, etc.
You can also try using a different port so the URL is different.
It takes some time to download and run the GWT app, particularly if you are using extra libraries, so wait for a few seconds to see if the app finally loaded.
What makes the app loading to fail randomly is something I don't know yet, but I suspect, as stated by Daniel Vaughan, that is related with a lack of computer resources, CPU, memory, etc.