1613072 - 'Late Writes' section always visible in about:telemetry even if no data about Late Writes available

Status: VERIFIED FIXED

(Toolkit :: Telemetry, defect, P1)

Description

[Sebastian Hengst [:aryx] (needinfo me if it's about an intermittent or backout)]

Latest Firefox Nightly 74.0a1 and Firefox Beta 73.0 20200203203546 on Windows 8.1

The 'Late Writes' section is always visible in about:telemetry even if no data about Late Writes is available: https://searchfox.org/mozilla-central/rev/2e355fa82aaa87e8424a9927c8136be184eeb6c7/toolkit/content/aboutTelemetry.js#2417-2419

Steps to reproduce:

1. Type about:telemetry into the address bar and press Enter.
2. Click on 'Late Writes' in the sidebar.

If the there are no Late Writes listed, that section should not be shown according to the intention of the code and how it worked until version 72.

Comment 1

[Chris H-C :chutten]

Ah. The lateWrites object isn't falsey, it contains a couple of empty members though. Lemme fix that real quick.

Comment 2

[Chris H-C :chutten]

Attachment: Bug 1613072 - Only show Late Writes if there are late writes r?janerik

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/d76528ca0015
Only show Late Writes if there are late writes r=janerik

Comment 4

[Natalia Csoregi [:nataliaCs]]

https://hg.mozilla.org/mozilla-central/rev/d76528ca0015

Comment 5

[Ryan VanderMeulen [:RyanVM]]

Is this worth a Beta uplift request?

Comment 6

[Chris H-C :chutten]

Over the course of the full Beta 69 cycle about:telemetry was loaded about 1250 times by at most 491 clients (more likely far fewer than that). I don't think it's worth it.

Comment 7

[Maria Berlinger [:mberlinger], Services QA]

I've managed to reproduce this issue on Firefox Nightly (2020-02-04) using Windows 10x64 by following the STR from comment 0.
This issue is verified fixed on Firefox 75.0b6 and Firefox 76.0a1 (2020-03-20) on the following OSes: Windows 10x64, macOS 10.15 and Ubuntu 18.04x64.