A redirect fetch followed or rejected was marked to drain: its body was
read and dropped until the server ended it, and the abort listener was
already removed. A body that never ends kept the connection busy after
cancellation and stalled a pool of one connection. Following or
rejecting a redirect now aborts its request, so the connection closes.
undici 7 leaves that connection open with its body paused, which stalls
the same pool; the follow-up request here gets a new connection.
The undici5 and undici7 npm cases now also run peers.ts against Node with
the vendored undici: header values with CR or LF, chunk-size lines that
are valid, malformed, overflowing or 1 MiB long, and fetch bodies that
are endless (read once, then cancelled), gzipped, truncated, empty,
corrupt, cut off, aborted after the headers, redirected while endless,
or carry six content codings. The undici5 case leaves out the Host
values, which undici 5.12 writes into the request head, and the two
fetch cases where undici 5.12 differs (six codings, and an endless
redirect, which fails with a TypeError in 5.12).
package-shims.test.ts compiles two programs in copies of the cases: one
reads 64 MiB chunk-size lines and 64 MiB plain and gzipped fetch bodies
from a separate Node peer and checks that RSS stays under 48 MiB (plain
lane), the other checks that the 5.x profile rejects a Host value with
CR or LF with undici 5.29.0's error.
Chris Tate