1647712 - Telemetry Lagging and Not Responding

Status: RESOLVED WONTFIX

(DevTools :: JSON Viewer, defect)

Description

[Pablo]

Telemetry lag and unresponsive when i check raw data

Found on
WIndows 10 64bit

On versions
Firefox Release 77.0.1 (not affected)
Firefox Beta 78 (not affected)
Firefox Nightly 79.0a1 (affected)

Steps

• Do any search in url bar
• go to about:telemetry
• click raw json
• click raw data
• try to resize window

Actual results
-window lags, becomes extremely slow, laptop fan starts to kick in

Expected result
should be fast, and resposive.

Comment 1

[Chris H-C :chutten]

Rehoming to JSON Viewer as that's the UI that's showing the JSON text.

Comment 2

[:Harald Kirschner :digitarald]

"raw json" in Nightly opens a blank tab for me and nothing loads.

Could you record a performance profile using profiler.firefox.com of the sluggish parts?

Comment 3

[:Harald Kirschner :digitarald]

(ni? Pablo for prior comment)

Comment 4

[Pablo]

hi harald, published here
https://share.firefox.dev/2NlpN4X

thanks.

Comment 5

[Oriol Brufau [:Oriol]]

The raw data tab probably contains a huge amount of text. When you resize the window, the text is laid out again, which produces a CPU spike since there is so much of it.
But if you just save the JSON into a .txt file and open it in Firefox, it should be the same. That is, I don't think this is a problem of the JSON viewer. Just a Firefox limitation when handling huge amounts of data.

Comment 6

[:Harald Kirschner :digitarald]

Agreed, raw data is not expected to be fast. The formatted tree can display specific data much faster and efficiently by hiding the rest.

In this case codemirror already stopped highlighting as well, so there isn't even any expensive codemirror operation.

Comment 7

[Pablo]

Hi Harald

The problem we are having is that this might be also a random problem too. It is weird that having a clean firefox with a new profile and just one search could cause such a problem. When we click "raw json" the window becomes completely unresponsive in a way that we just have to close firefox. After clicking Raw json if i resize the screen it takes 3 or 4 seconds to resize. We sometimes even noticed that firefox window just stopped responding.

For example i tried to do a mozregression for this bug. and the first mozregression , where it started to fail on june 6th:
But then i tried to do another mozregression and it failed on May 31st where the window started to lag incredibly, so i think it might be random, one thing. im sure is that on older builds for some moths ago this is not happening at all, besides we are just launching firefox, creating a new tab with a search, and another tab to go to about:telemetry

here is another capture i have while running with this issue https://share.firefox.dev/2VgVGje

mozregression result:

app_name: firefox
build_date: 2020-06-06 01:36:02.168000
build_file: C:\Users\Pablo Muir.mozilla\mozregression\persist\094e467aacd7-pgo--autoland--target.zip
build_type: inbound
build_url: https://firefox-ci-tc.services.mozilla.com/api/queue/v1/task/DzRZFb4YQVaQPiquyJa4gA/runs/0/artifacts/public%2Fbuild%2Ftarget.zip
changeset: 094e467aacd74fed6fcccc29f807bc4dac016440
pushlog_url: https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=97d587a1f2d1bd4c23105c7552f51f8c8244fc2c&tochange=094e467aacd74fed6fcccc29f807bc4dac016440
repo_name: autoland
repo_url: https://hg.mozilla.org/integration/autoland
task_id: DzRZFb4YQVaQPiquyJa4gA

so i wonder why if we run the same steps sometimes there is no lag, and why sometimes it starts to lag.
Im not the only one that saw this problem.

regards.

Comment 8

[Oriol Brufau [:Oriol]]

I suspect you get inconsistent results because the telemetry accumulated more data.
You should download the JSON, and then bisect that file instead of going to about:telemetry

Comment 9

[:Harald Kirschner :digitarald]

+1 on what Orion said – opening the same JSON file would help to do a proper regression analysis.