Reduce websocket subscription dispatch and receive-loop overhead - #678
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maedula wants to merge 2 commits into
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Reduce websocket subscription dispatch and receive-loop overhead#678maedula wants to merge 2 commits into
maedula wants to merge 2 commits into
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added 2 commits
July 16, 2026 15:55
…comingMessageDispatcher Every active GraphQL subscription independently subscribed to the shared incoming websocket message stream and filtered it with its own Where(response.Id == myId) predicate, so the per-message cost scaled with the number of concurrent subscriptions instead of being constant. IncomingMessageDispatcher keeps a single subscription to the shared stream and routes each message directly to its owner via a dictionary lookup.
…sync pump Observable.Defer(() => GetReceiveTask().ToObservable()).Repeat().Catch(...).Publish() allocated a SlowTaskObservable (bridging via Task.ContinueWith) and re-entered Repeat's TailRecursiveSink trampoline for every single incoming websocket message. Profiling showed this Rx plumbing, not application logic, was the largest CPU and allocation cost in the receive path. A plain async while loop pushing into a Subject gives the same hot/multicast/run-until-cancelled semantics without the per-message Rx bridging overhead.
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Summary
Wheresubscriptions on the shared incoming stream with one ID-keyed dispatcherTask -> Observable -> Repeatreceive chain with an owned async receive pumpThis changes incoming message routing from broadcasting every message to every active operation to a single dictionary lookup, and removes the Rx task-bridging objects allocated for each received message.
Validation
dotnet test tests/GraphQL.Integration.Tests/GraphQL.Integration.Tests.csproj -c Releasedotnet build src/GraphQL.Client/GraphQL.Client.csproj -c Release -f netstandard2.0