1575869 - Adding an expression in the watch panel makes the Expressions panel render 5 times

Status: NEW

(DevTools :: Debugger, task, P3)

Description

[Nicolas Chevobbe [:nchevobbe]]

Steps to reproduce

1. Open the debugger
2. Open the browser toolbox debugger, and put a logpoint in the Expression component render function (like "render", this.props)
3. In the regular debugger, add a watch expression (e.g. 1)

Expected results

The logpoint produces one or two render messages

Actual results

The logpoint is hit 5 times after I hit the Enter key.

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Looks like we're dispatching a bunch of actions that each trigger renders? And shouldComponentUpdate may not be as efficient as we think.

Comment 1

[:Harald Kirschner :digitarald]

Maybe also related to bug 1569829 and other flickering issues; that Debugger thrashes UI with unnecessary state changes and renderings?

Comment 2

[Jason Laster [:jlast]]

I was not able to reproduce 5 renders

I saw two for new Expressions and 3 for updates

https://www.loom.com/share/a34ce785ddce4279879631385b2b5bd6