fetch() hangs when receiving large headers over HTTP/2

[danopia]

Version: Deno 2.1.7

I've found that Deno's h2 implementation is hanging fetch() calls when an HTTP2 error occurs.
In this case, the response headers are very large (~20kb). Deno seems to be dropping the transaction because of stream error REQUEST_HEADER_FIELDS_TOO_LARGE without resolving or rejecting the promise, so the fetch() call waits forever.

reproduction

I have set up a reproduction endpoint that can be used like so:

# expected behavior:
$ curl https://eo82u4jujnkymoi.m.pipedream.net
You got the response!

# will just hang forever:
$ deno run --allow-net https://deno.land/[email protected]/examples/curl.ts https://eo82u4jujnkymoi.m.pipedream.net
# ...

debug log

I have captured a debug log, which is how I was finally able to see what the actual issue was (I spent at least an hour finding the trigger 😓)

$ deno run -L debug --allow-net https://deno.land/[email protected]/examples/curl.ts https://eo82u4jujnkymoi.m.pipedream.net
# ... deno startup
DEBUG RS - hyper_util::client::legacy::connect::dns:121 - resolve; host=eo82u4jujnkymoi.m.pipedream.net
DEBUG RS - hyper_util::client::legacy::connect::http:657 - connecting to 44.198.101.178:443
DEBUG RS - hyper_util::client::legacy::connect::http:660 - connected to 44.198.101.178:443
DEBUG RS - h2::client:1281 - binding client connection
DEBUG RS - h2::client:1286 - client connection bound
DEBUG RS - h2::codec::framed_write:213 - send frame=Settings { flags: (0x0), enable_push: 0, initial_window_size: 2097152, max_frame_size: 16384, max_header_list_size: 16384 }
DEBUG RS - h2::proto::connection:138 - Connection; peer=Client
DEBUG RS - hyper_util::client::legacy::pool:396 - pooling idle connection for ("https", eo82u4jujnkymoi.m.pipedream.net)
DEBUG RS - h2::codec::framed_read:405 - received frame=Settings { flags: (0x0), max_concurrent_streams: 128, initial_window_size: 65536, max_frame_size: 16777215 }
DEBUG RS - h2::codec::framed_write:213 - send frame=Settings { flags: (0x1: ACK) }
DEBUG RS - h2::codec::framed_read:405 - received frame=WindowUpdate { stream_id: StreamId(0), size_increment: 2147418112 }
DEBUG RS - h2::codec::framed_write:213 - send frame=WindowUpdate { stream_id: StreamId(0), size_increment: 5177345 }
DEBUG RS - h2::codec::framed_write:213 - send frame=Headers { stream_id: StreamId(1), flags: (0x5: END_HEADERS | END_STREAM) }
DEBUG RS - h2::codec::framed_read:405 - received frame=Settings { flags: (0x1: ACK) }
DEBUG RS - h2::proto::settings:56 - received settings ACK; applying Settings { flags: (0x0), enable_push: 0, initial_window_size: 2097152, max_frame_size: 16384, max_header_list_size: 16384 }
DEBUG RS - h2::codec::framed_read:405 - received frame=Headers { stream_id: StreamId(1), flags: (0x4: END_HEADERS) }
DEBUG RS - h2::proto::streams::recv:203 - stream error REQUEST_HEADER_FIELDS_TOO_LARGE -- recv_headers: frame is over size; stream=StreamId(1)
DEBUG RS - h2::codec::framed_read:405 - received frame=Data { stream_id: StreamId(1) }
DEBUG RS - h2::codec::framed_read:405 - received frame=Data { stream_id: StreamId(1), flags: (0x1: END_STREAM) }
DEBUG RS - h2::codec::framed_write:213 - send frame=Reset { stream_id: StreamId(1), error_code: REFUSED_STREAM }
# hangs forever

workaround

Disabling http2 for the fetch call via Deno.createHttpClient({http2: false})