Enforce exclusive checker acquisition - #64543
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Jake Bailey (jakebailey) merged 1 commit intoSep 29, 2026
Merged
Jake Bailey (jakebailey) merged 1 commit into
Jake Bailey (jakebailey) merged 1 commit into
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Request identity does not imply exclusive ownership: parallel workers inherit their parent's request ID and can otherwise mutate the same checker concurrently. Request affinity must only select idle checkers, not bypass acquisition. Nested language-service operations must share an explicitly acquired checker or finish their acquisition before the next operation. This keeps ownership independent of context propagation and avoids requiring parallel compiler operations to strip request metadata.
Jake Bailey (jakebailey)
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a balanced review from Copilot
September 29, 2026 21:39
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Copilot review overview
🔵 Needs a closer look
The central checker-pool concurrency contract warrants final human review despite focused regression coverage.
Review effort: Balanced
Findings: None
What changed in this PR
Enforces exclusive checker acquisition while preserving released-checker affinity and removes nested acquisitions in language-service paths.
Changes:
- Prevents request IDs from bypassing checker exclusivity.
- Reuses acquired checkers or releases them before nested operations.
- Adds checker contention, diagnostics, and content-mapper regressions.
| File | Description |
|---|---|
tsc/internal/compiler/checkerpool.go |
Documents exclusive, non-reentrant acquisition. |
tsc/internal/project/checkerpool.go |
Enforces semaphore acquisition for every checkout. |
tsc/internal/project/checkerpool_test.go |
Tests affinity and same-request contention. |
tsc/internal/lsp/server_flakydiagnostics_test.go |
Covers parallel diagnostic/emit behavior. |
tsc/internal/ls/inlay_hints.go |
Releases each mapped-range checker promptly. |
tsc/internal/ls/findallreferences.go |
Passes the existing checker into nested reference logic. |
tsc/internal/ls/codeactions_importfixes.go |
Shares one checker across import-fix processing. |
tsc/internal/ls/codeactions_fixmissingtypeannotation.go |
Collects diagnostics before acquiring the fixer checker. |
tsc/internal/ls/codeactions_fixclassincorrectlyimplementsinterface.go |
Avoids diagnostic collection while holding a checker. |
tsc/internal/fourslash/tests/contentMapperInlayHints_test.go |
Adds mapped-range checker-release coverage. |
tsc/testdata/baselines/reference/fourslash/inlayHints/contentMapperInlayHintsReleaseEachRange.baseline |
Records expected inlay hints. |
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Andrew Branch (andrewbranch)
approved these changes
Sep 29, 2026
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This is a replacement for #64513.
I think it's probably not worth trying to be clever about allowing checker reuse reentrancy through request chains; as seen in the linked PR and crashes, it's easy to get into situations where the checker becomes concurrently used or mismanaged.
Dropping this is in some ways a simplification, but is generally a noop, because often the context was being passed just to eventually ask for a checker anyway. We can still reuse checkers we previously released if they're there.
Closes #64513