Closed Bug 1630053 Opened 11 months ago Closed 9 months ago

Add telemetry for cookie purging


(Core :: Privacy: Anti-Tracking, task, P1)




Tracking Status
firefox78 --- fixed


(Reporter: johannh, Assigned: johannh)


(Blocks 1 open bug)



(2 files)

Steve, Arthur, we should probably measure how purging is performing for our users, both from a perf standpoint as well as in terms of how effective it is at clearing cookies.

In our next meeting we should discuss some measurements and possibly success criteria.


  1. Is cookie purging effective? Ideally we'd look at which origins are being purged and how often, but can't do that without something like Prio. Instead, we can measure the number of origins purged and the number of origins not purged.
  2. Is recently accessed storage the right way to determine what storage to purge? We can measure the time between the current purge and the previous purge. If many clients are consistently above our lookback window, then we may need to consider a different approach or increase the lookback window.
  3. Is our approach performant? We can measure the total time spent on each purge event.
Assignee: nobody → jhofmann
Priority: -- → P1
Severity: -- → S3

It would also be great to understand how frequently an origin which once had user interaction is purged. When we chatted about this during our meeting we said: "Can generally record how many permission entries a user has and how old the interaction permissions are.", but perhaps there's a better way to capture this?

Attached file Data Review Request
Attachment #9150251 - Flags: data-review?(tdsmith)
Comment on attachment 9150251 [details]
Data Review Request

lgtm, ty!

1) Is there or will there be **documentation** that describes the schema for the ultimate data set in a public, complete, and accurate way?

Yes, Histograms.json and the probe dictionary.

2) Is there a control mechanism that allows the user to turn the data collection on and off?

Yes, the Firefox telemetry opt-out.

3) If the request is for permanent data collection, is there someone who will monitor the data over time?


4) Using the **[category system of data types](** on the Mozilla wiki, what collection type of data do the requested measurements fall under?

These round up to category 2; there are no category 3 collections in this dataset.

5) Is the data collection request for default-on or default-off?


6) Does the instrumentation include the addition of **any *new* identifiers** (whether anonymous or otherwise; e.g., username, random IDs, etc.  See the appendix for more details)?


7) Is the data collection covered by the existing Firefox privacy notice? 


8) Does there need to be a check-in in the future to determine whether to renew the data?

Johann is responsible for renewing the collection as necessary.

9) Does the data collection use a third-party collection tool?

Attachment #9150251 - Flags: data-review?(tdsmith) → data-review+
Pushed by
Add telemetry for cookie purging. r=englehardt,ewright
Closed: 9 months ago
Resolution: --- → FIXED
Target Milestone: --- → mozilla78
See Also: → 1656134
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