why sometimes my EXTJS Web application become unresponsive on chrome

[Rahul Tiwari]

We are facing some bizarre issue with our web application when we run it on chrome. All the operations on the application executes as expected but on some days when we execute very basic and common features of the application, chrome starts displaying this pop-up stating : - "The following page has become unresponsive. You can wait for it to become responsive or kill it. With two options of Wait and Kill."

So we are wondering, why sometimes application showing this unexpected behavior. So need your help to figure out what could be possible cause of this.

Little Application Background : 1. Analytics application so having multiple tabs with multiple charts and Grids on each tabs. 2. A DOM intensive application with operations on large data. 3. Developed using EXTJs -4.2 for complete UI and JAVA for the Backend, 4. CometD as Messaging server. 4. Appplication deployed on Jetty server.

So we have figured out few areas which could have been causing problems but having hard time to identify exact cause. Possible areas of concern : 1. Rendering of charts, grids and other UI component on Chorme. 2. Slow internet or network by application accessed. 3. Heavy request to the sever and heavy response data from the server.

So any thoughts what could be causing this possible. Also are there any tools or plugins etc. which can be useful to identify exact problematic area.

[PhistucK]

This message is displayed whenever your JavaScript code runs for a long time (15 seconds or more, if I remember correctly). Very long rendering phases may also cause this, yes.

This could be due to a bug in the JavaScript code (and certain conditions makes the application go through a certain code path that runs for a long time, or even infinitely), or it could be a JavaScript engine issue (some optimizations may be buggy and cause unexpected, incorrect values to be returned from simple operations which in turn go through an application code path that runs infinitely). It could also be due to rendering many complex element on the screen. Finally, it could be due to a bad interaction with a plugin/extension.

It is probably not due to a slow network (unless you are using XMLHttpRequest synchronously, which is a very bad practice anyway), unless you code does something different when responses come in slowly.

You can use three tools for debugging the situation, however, you will have to reproduce the situation in order to debug it.

- In order to eliminate the bad plugin/extension interaction concern - go to chrome:plugins and disable all of the plugins, same for chrome:extensions.

- In order to debug long JavaScript or rendering phases, you can use the Timeline panel in the Developer Tools.

- If those two do not yield anything (or the Timeline panel never successfully gathers the data), you can use chrome:tracing, which is very verbose, but might give a hint.

Also, is it a new issue (a regression), or did it always exist (or the application code is fairly recent)?

If you find that it is most probably not an application issue, but likely a browser issue, you can search crbug.com for an existing issue and star it. If you cannot find one, file a new issue using the "New issue" link on the same page.

Please, do not add a "+1" or "Me too" or "Confirmed" (or similar) comment. It just wastes the time of Chrome engineers and sends unnecessary e-mails to all of the people who starred the issue.

You can reply with a link to the found or created issue and might get triaged (and fixed) faster.

Thank you.

☆PhistucK

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