1997372 - Potential regression: http/3 requests failing sporadically on some google backends

Status: UNCONFIRMED

(Core :: Networking: HTTP, defect)

Description

[Olaf Otto]

Attachment: QUIC debug log of an affected session, Single page load + Adjacent resource + XHR loads

Since about a week, our users on both Windows and Linux platform reported that one of our GCP hosted Grafana Platforms became extremely slow and failed to load some graph data on almost every page load.

Our investigation revealed that this only happens in Firefox. Here, Firefox connects to the GCP backend using QUIC (HTTP/3), and performs a number of XHR POST requests to a HTTPS backend. These requests cause queries on the DB that will be answered with some delay (0.5-3 seconds) at most. However, in Firefox, some of these POST requests block, remain without progress for 5-10 seconds, then show up as with NS_ERROR_NET_RESET. The respective requests do not show up in the load balancer logs.

When deactivating HTTP/3 (about:config -> network.http.http3.enable = false), the problem can no longer be reproduced. I suspect this is a regression of https://bugzilla.mozilla.org/show_bug.cgi?id=1734198.

I have enabled QUIC logging, the affected conversation is attached.

Comment 1

[Olaf Otto]

Attachment: dev tool network view of the issue.png

DEV tools network analysis view of the effect of the issue

Comment 2

[Sunil Mayya]

Thanks Olaf for filing the bug and qlogs.
Could you kindly capture HTTP3 networking logs please for this issue as well as this will speed up the investigation.
Go to about:logging and select HTTP/3 preset and logging to a file. If you are concerned about privacy kindly share the logs to [e-mail]
Thanks