1026850 - Experiment system might get active experiment in a confused state if telemetry was disabled

Status: RESOLVED WONTFIX

(Firefox Health Report Graveyard :: Client: Desktop, defect, P4)

Description

[:Felipe Gomes (needinfo for replies!)]

STR:
 - install an experiment
 - disable telemetry (or anything that causes gExperimentsEnabled to become false)
 - restart browser

After a restart, the experiment was disabled, but if you go to the Experiments tab in the Add-ons Manager, you'll see it as "Complete - NaN days ago".
I don't recall if the experiment also got fully uninstalled after a subsequent restart, but I think it did (it's probably the right behavior).

So it looks like only the UI might be messed up, but I didn't investigate deeply.

Comment 1

[Georg Fritzsche [:gfritzsche]]

I did a quick investigation here.
This shouldn't happen for normal users because the experiments manager observes toolkit.telemetry.enabled - if you disable telemetry we stop & uninstall any running experiments.
So what's required to reproduce this is to either:
(1) have telemetry disabled & force experiments to initialize or
(2) have an active experiment, shutdown Firefox, manually set the pref to false in $PROFILEDIR/prefs.js or
(3) disable telemetry when an experiment is active, but crash/throw so that we don't get to actually uninstalling the experiment

(3) is an actual, but less likely concern. We should probably fix this by checking & uninstalling any stale addons in ExperimentsService.js when experiments are not enabled.

Comment 2

[Georg Fritzsche [:gfritzsche]]

When we find experiments are disabled around here:
http://hg.mozilla.org/mozilla-central/annotate/37f08ddaea48/browser/experiments/ExperimentsService.js#l72
... we should check for any remaining experiment addons and just uninstall them.

The two functions here show how to get the installed experiment addons and uninstall them:
http://hg.mozilla.org/mozilla-central/annotate/37f08ddaea48/browser/experiments/Experiments.jsm#l208

Comment 3

[Kamil Jozwiak [:kjozwiak]]

Attachment: issue.png

Looks like this is still an issue. I ran into this today while going through bug # 1003362. Once the experiment was disabled and about:addons refreshed, the "Complete" field appeared as "NaN days ago" (attached screenshot).

Comment 4

[Georg Fritzsche [:gfritzsche]]

Telemetry experiments were removed from Firefox per bug 1415284.