[tailscale] vendor/golang.org/x/net: backport lazy hpack table maps
Backport upstream x/net commit 99c3b0a8f463 (CL 807260), "http2/hpack:
build the table lookup maps lazily, only for encoders". It landed on
x/net master after the go1.27 vendor branch was cut, so it is in Go
1.28's vendored x/net but not Go 1.27's.
The hpack table byName and byNameValue maps are only read by encoders,
but decoder dynamic tables maintained them anyway for every entry. For
servers with many mostly-idle HTTP/2 connections, each pinning a
decoder dynamic table for the connection's lifetime, those maps are a
meaningful fraction of per-connection memory: on one proxy instance
with ~124k long-poll connections, hpack table maps accounted for
~230MB of live heap.
This modifies only the vendored files, leaving go.mod and modules.txt
at the go1.27 vendor branch pseudo-version. Drop this patch at the
go1.28 rebase; it is upstream there.
Updates tailscale/corp#29053
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
Change-Id: I27c8835c73221b48958ce47fc6f784c43fb4da51
We backported this Go 1.28 change to our Go 1.27 tree:
commit b67ddcd
Date: Tue Sep 1 01:42:45 2026 +0000