[Fusion] Reduce per request allocations#9512
Merged
michaelstaib merged 6 commits intomainfrom Apr 8, 2026
Merged
Conversation
Contributor
There was a problem hiding this comment.
Pull request overview
This PR focuses on reducing per-request allocations in Fusion execution by replacing temporary collections with pooled buffers and tighter data structures.
Changes:
- Replace
Path.ToList()-based segment materialization withArrayPool-backed buffers and a newPath.CopyTo(Span<object>)API. - Pool
VariableValues[]allocations inFetchResultStoreand copy out the final immutable result. - Reduce runtime overhead in execution state tracking (bitset instead of
HashSet<int>) and avoid repeated schema name computation during subscription event processing.
Reviewed changes
Copilot reviewed 8 out of 8 changed files in this pull request and generated 11 comments.
Show a summary per file
| File | Description |
|---|---|
| src/HotChocolate/Fusion/src/Fusion.Execution/Execution/Results/PathUtilities.cs | Uses pooled object[] buffers to compare path segments without allocating lists. |
| src/HotChocolate/Fusion/src/Fusion.Execution/Execution/Results/FetchResultStore.cs | Uses pooled buffers for path traversal and variable value set construction/finalization. |
| src/HotChocolate/Fusion/src/Fusion.Execution/Execution/OperationPlanExecutor.cs | Caches schemaName once for subscription event diagnostics. |
| src/HotChocolate/Fusion/src/Fusion.Execution/Execution/OperationPlanContext.Pooling.cs | Ensures pooled execution state resources are released on context destruction. |
| src/HotChocolate/Fusion/src/Fusion.Execution/Execution/OperationPlanContext.cs | Reduces allocations when materializing skipped definitions and forwarded variable field nodes. |
| src/HotChocolate/Fusion/src/Fusion.Execution/Execution/ExecutionState.cs | Replaces skipped/failed tracking with a pooled bitset and pools internal arrays. |
| src/HotChocolate/Fusion/src/Fusion.Execution/Execution/Clients/SourceSchemaErrors.cs | Switches to Path.CopyTo and reuses a cached shared ArrayPool<object>. |
| src/HotChocolate/Core/src/Execution.Abstractions/Path.cs | Renames span-based path materialization to CopyTo(Span<object>) and updates docs. |
💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.
Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## main #9512 +/- ##
============================
============================
☔ View full report in Codecov by Sentry. 🚀 New features to boost your workflow:
|
This was referenced May 1, 2026
Open
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
No description provided.