Contributor Comments

Link to the original Jira ticket: https://issues.apache.org/jira/browse/METRON-2272

The problem

Every time we instantiate an ace editor instance on an angular component, it immediately forces angular to re-render the entire application very frequently (every 300-500 ms). For the first time, it's not that noticeable but after a while it can be annoying because it leads to performance issues and when you type something an ace editor input, it's gonna be really slow.

The performance slowdown is even more noticeable when you change between manual and normal query mode many times (This is how we have caught it).

Under the hood the frequent updates make Angular's zone manager very busy because it forces it to do a lot of dirty checking. To be fair it really is an issue only in development mode when dirty checking require more resource consumption.

Testing

Checkout the latest master branch and open the Alerts UI. Go to the alerts-list page and start typing something in the search input field at the top of the page just to get the feeling how it should behave normally. Then change between "Manual query" and "Query builder" mode a few times (e.g. 15-20 times). Make sure you're in "Query builder" mode and type something again in the search input field. See how slow and laggy it is?

Now checkout METRON-2272 and repeat the previous steps. Like a breath of a fresh air, isn't it?

Further

As a bonus I also destroy the ace instances when angular is about to detach the component from the DOM. My assumption is that we could achieve even bigger performance boost if we convert our ace editor directive to a component and change the changeDetection strategy to onPush. I didn't want to do that in this PR in order to make the review process easier.

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