Schema design, N+1 resolution, streaming RPC, and choosing a protocol per consumer.
4 questions in Backend Engineering.
A gRPC deadline. gRPC sets none by default, so a client waits as long as the server takes, and every caller up the chain holds a thread or stream with it. Set a deadline at the edge, propagate the remaining budget on every hop, stop work on cancellation, and retry only inside what is left.
Estimate GraphQL query cost before execution, multiplying list fields by their enforced page size, and reject anything over budget. Add a depth limit as a backstop, persisted queries for your own apps, execution timeouts, and per-client rate limits counted in cost points, not requests.
Choose per consumer: GraphQL where many client shapes make over-fetching the problem, gRPC for internal traffic wanting typed generated stubs and streaming, plain JSON over HTTP for partners who want curl and a CDN. Then batch your resolvers, because the N+1 is structural.
gRPC multiplexes many calls over one long-lived HTTP/2 connection, so a balancer that distributes connections pins each client to one backend for its lifetime. Balance per request with an HTTP/2-aware proxy or client-side subchannels, and bound connection age so scaling out actually moves traffic.