Background

The underlying hyper/h2 implementation already supports configuring
http2_max_pending_accept_reset_streams, but this option is currently not
exposed by Volo's gRPC server.

In our production environment, we frequently observe the following warning:

recv_reset; remotely-reset pending-accept streams reached limit (20)

Representative logs:

{"timestamp":"2026-07-15T10:13:08.670091417+08:00","level":"WARN","fields":{"message":"recv_reset; remotely-reset pending-accept streams reached limit (20)"},"target":"h2::proto::streams::recv"}

{"timestamp":"2026-07-15T10:13:08.682643952+08:00","level":"WARN","fields":{"message":"recv_reset; remotely-reset pending-accept streams reached limit (20)"},"target":"h2::proto::streams::recv"}

{"timestamp":"2026-07-15T10:13:08.758969319+08:00","level":"WARN","fields":{"message":"recv_reset; remotely-reset pending-accept streams reached limit (20)"},"target":"h2::proto::streams::recv"}

These warnings are repeatedly emitted under load, indicating that the default
limit (20) is insufficient for some workloads.

Reference

Hyper exposes this configuration because of the discussion in:

hyperium/hyper#2877

Proposed API

Expose the configuration through the gRPC server builder, similar to the
existing HTTP/2 configuration methods.

pub fn http2_max_pending_accept_reset_streams(
    mut self,
    max: impl Into<Option<usize>>,
) -> Self {
    self.http2_config.max_pending_accept_reset_streams = max.into();
    self
}

Store the value in Http2Config:

pub(crate) max_pending_accept_reset_streams: Option<usize>,

with the default value:

max_pending_accept_reset_streams: None,

Finally, propagate the configuration into Hyper:

server
    .http2()
    // ...
    .max_pending_accept_reset_streams(
        self.http2_config.max_pending_accept_reset_streams,
    );

Benefits

• Allows applications to tune the limit for workloads with frequent HTTP/2 stream resets.
• Keeps the current behavior unchanged by default.
• Aligns Volo with the underlying Hyper API.
• The implementation is straightforward and fully backward compatible.