我应该怎么做才能加快使用MVC的慢GWT应用程序 [英] What should I do to speed up a slow GWT app using MVC

问题描述

描述：

我的应用程序使用MVC并且变得非常慢。


• 应用程序有5个组合，每个组合代表不同的数据，并不总是显示


• 该应用程序使用MVC，我将模型传递给每个当发生更新时复合。


• 每次收到通知时，我都会重新构建树（以及所有树项），但是，只有其中一个树项会发生更改，所以这是可能是浪费。
  
• 由于应用程序的风格，我甚至必须通知（）以获取无关紧要的内容，例如更改文本框中的文本或选择菜单，因为我有一个保存的图标那么只要树项中的某些内容发生更改，它就会变为未保存。 所有组合实现相同的Observer接口，因此每个notify（）都会得到更新。

有人可以给我一些提示，告诉我应该如何加快这款应用的速度。以上哪一个可能比其他CPU更饿，即正在用<每个notify（）函数将使用20个CPU时间，我需要重新设计它吗？我应该创建一个单独的接口，如SaveStateChanged，它只会通知树，或者这只是浪费时间。

解决方案

当应用程序变慢时，大多数时间通常不会花费在自己执行JavaScript计算上（例如，我不相信，只是调用很多观察者是一个问题 - 这取决于他们是什么做！）。很多时候，缓慢是由诸如冗余布局之类的事情引起的（例如，当每个观察者导致布局调用时）。有时候，大量的DOM操作也可能成为问题（主要是IE浏览器）。

我建议在Speed Tracer上玩一点，特别是冗余布局示例。如果这不是您的应用程序中的特定问题，您应该可以采取与示例中所示类似的方法进行跟踪。使用 markTimeline（String） ，以便在Speed Tracer的图表中清楚地显示代码的特殊部分。

I have changed my app to use MVC and it has gotten pretty slow.

Description:

• The application has a number of 5 composites, each composite represents different data and is not always showing
• The app is using MVC and I am passing the model to each composite when an update occurs.
• I am rebuilding a Tree (and all tree items) every time a notify is recieved, however, only one of the tree items would have changed, so this is possibly a waste.
• Due to the style of the app I have to even notify() for insignificant things like changing the text in a text box or selecting a menu because I have a saved icon that turn to unsaved whenever something is changed in the tree Item.
• All the composites are implementing the same Observer Interface, so all are getting updated on every notify().

Can someone give me some tips on what I should do to speed this app up. Which of the above might be more CPU hungry than others, ie, is rebuilding a Tree with < 20 items on every notify() going to use that much CPU time, do I need to re-design this? Should I create a seperate interface such as SaveStateChanged that will only notify the tree, or is this just a waste of time.

解决方案

When an application is getting slow, then most time is often not spent performing the JavaScript calculations themselves (e. g. I don't believe, that just calling a lot of observers is a problem - it depends on what they do!). Very often, slowness is caused by things like redundant layout (e. g. when each of the observers causes a layout call). Sometimes, lots of DOM manipulations can also be a problem (mainly with Internet Explorer).

I would suggest to play a little bit with Speed Tracer, especially the redundant layout example. If that's not the specific problem in your application, you should be able to take a similar approach as shown in the example to track it down. Use markTimeline("String") to make special parts of your code show up clearly in Speed Tracer's graphs.

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