1498193 - Implement the 'pause' feature of the new about:performance

Status: RESOLVED WONTFIX

(Toolkit :: Performance Monitoring, enhancement)

Description

[Florian Quèze [:florian]]

The UX mockup at https://mozilla.invisionapp.com/share/SDOE65KGU2Z#/screens has pause buttons.

Putting a tab on pause will suspend JS in the tab:
https://searchfox.org/mozilla-central/rev/924e3d96d81a40d2f0eec1db5f74fc6594337128/devtools/server/actors/targets/browsing-context.js#1195-1197 is how the debugger does it, we can likely use the same code.

When a tab is paused, the pause icon will be replaced with a 'play' icon that can be clicked to resume JS execution in the tab.

To avoid the risk of users being confused by tabs where JS is paused, whenever a tab is selected we'll resume JS execution in it.

Comment 1

[Andreas Jung]

(In reply to Florian Quèze [:florian] from comment #0)
> To avoid the risk of users being confused by tabs where JS is paused,
> whenever a tab is selected we'll resume JS execution in it.

Does this mean the active tab of an inactive / background window can't be paused?
This would be too bad because that's actually the most useful case.
Pausing background tabs is nice but those are already throttled anyway.

Comment 2

[Nathan Froyd [:froydnj]]

How closely is this related to tab unloading?

Comment 3

[Florian Quèze [:florian]]

(In reply to Nathan Froyd [:froydnj] from comment #2)

How closely is this related to tab unloading?

The idea here was to just do the equivalent of pressing the pause button in the JS debugger. So everything would remain in memory.

Comment 4

[Gabriele Svelto [:gsvelto]]

(In reply to Florian Quèze [:florian] from comment #3)

The idea here was to just do the equivalent of pressing the pause button in the JS debugger. So everything would remain in memory.

Still, knowing the tab won't be used immediately it might be useful to minimize the memory it uses by GC/CC'ing it.

Comment 5

[Florian Quèze [:florian]]

Mass closing about:performance bugs as about:performance has been removed in bug 1836191 in favor of about:processes which displays more accurate data. If this bug still applies to about:processes, feel free to reopen and change the summary.