Implement connection pooling with request pipelining for network services to optimize resource usage and improve throughput. Pool should manage three resource levels: 1. Channels (TCP connections): Share between multiple clients with HTTP/2 multiplexing 2. Clients: Acquire from channel pool, return when done 3. Streams: Reuse for multiple requests with controlled queue depth Example implementation: ```rust const CLIENTS_PER_CHANNEL: usize = 16; const STREAM_QUEUE_DEPTH: usize = 2; pub struct ChannelPool { channels: Mutex>, } pub struct ClientPool { channel_pool: Arc, idle: Mutex>, } pub struct StreamPool { client_pool: Arc, streams: Arc>>, } ``` Key principles: - Use HTTP/2 stream multiplexing to share TCP connections - Pipeline multiple requests (queue depth 2-3) to mask network latency - Return resources to pool promptly to enable reuse - Implement proper backpressure through queue depth limits - Consider cleanup of idle resources after timeout period