1222338 - 301 + DNS failure leads to massive CPU spike

Status: NEW

(Core :: Networking: DNS, defect, P3)

Description

[Justin Dolske [:Dolske]]

Attachment: Browser toolbox / network screenshot

I just registered a domain, and tried loading it before DNS was fully propagated (because I am impatient). I was a little surprised to see Firefox jump to 200% CPU when doing this.

At first, using devtools, it looked like an infinite redirect loop between www.site.com and site.com... But it's a little more subtle.

From my command line, "curl site.com" results in a "curl: (6) Could not resolve host: site.com", whereas "curl www.site.com" results in a 301 to site.com (non-www). 

So I think what's happening is that Firefox sees the no-www site.com lookup fail, helpfully tries to load www.site.com instead, and gets 301'd back to where it started. Lather rinse repeat. Seems like Firefox should not do the "helpful" www fixup when it knows there's a 301 loop, or when it's not the original URL entered in the URL bar.

[I have my Dreamhost config set up so that the 301 to the non-www host is expected. Presumably this specific case will start working as soon as the non-www DNS starts to resolve correctly.]

Comment 1

[Vitor]

I would like to patch this bug. The solution would actually be to check if there's a 301 loop and not do the "helpful" www fixup?

Comment 2

[Firefox Bug Husbandry Bot]

Bulk change to priority: https://bugzilla.mozilla.org/show_bug.cgi?id=1399258

Comment 3

[Firefox Bug Husbandry Bot]

Bulk change to priority: https://bugzilla.mozilla.org/show_bug.cgi?id=1399258