1952221 - Add telemetry to track potential breakage due to larger DNS grace period

Status: RESOLVED FIXED

(Core :: Networking: DNS, enhancement, P2)

Description

[Oskar Mansfeld]

See comment #5 in bug 1937022

Re: Follow up experiment with grace period increased

I think it makes sense to implement telemetry that checks when the longer grace period could lead to breakage.

My thought process is that when the cache renewal that is triggered when an entry is in the grace period produces a result that is different than the cached entry then we have potentially broken something by introducing the grace period and should record that in telemetry so we can see if the experiment has a negative impact (or how big that impact is).

Comment 1

[Oskar Mansfeld]

(Some additional info from :valentin (he/him) from comment #6 on bug 1937022

I'm very much in favor of adding some telemetry for this, though the grace period isn't the only case in which we refresh DNS records.

If you have tab A and B open to the same origin, and tab B gets force-refreshed, that would also update the DNS cache entries available to tab A, which is similar to the grace period refresh, but I'll grant you that the grace period is something we'll probably hit more often.

Regardless, I think this is good telemetry to have.
I'm also quite curious to see how often the refreshed DNS request fails.

Comment 2

[Oskar Mansfeld]

Attachment: Bug 1952221 - Add telemetry for grace period induced DNS cache renewals. r=#necko

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/6c981224a5c4
Add telemetry for grace period induced DNS cache renewals. r=necko-reviewers,valentin

Comment 4

[amarc]

Backed out for causing build bustages @ nsHostResolver.cpp

• Backout link
• Push with failures
• Failure Log

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/d50b0d4c7302
Add telemetry for grace period induced DNS cache renewals. r=necko-reviewers,valentin

Comment 6

[Atila Butkovits]

https://hg.mozilla.org/mozilla-central/rev/d50b0d4c7302