Fix cross-session system Python cache misses on remotes by StellaHuang95 · Pull Request #1951 · microsoft/vscode-python-environments

Stella Huang (StellaHuang95) · 2026-10-23T20:13:21Z

Summary

mirror the global system Python selection into workspaceState so the same remote workspace survives a cold globalState
preserve workspace-first lookup with the existing global fallback for legacy and brand-new workspace behavior
version mirrored entries and tombstones so partial Memento writes cannot return or resurrect an older selection
serialize global cache mutations and compare before stale invalidation so concurrent selections cannot be erased
invalidate both layers only when the cached executable is definitively missing, while preserving transient PET failures for retry
make failed multi-key persistent-state clears settle all updates and release later reads/writes
add focused coverage for precedence, migration, partial failures, stale paths, races, clear recovery, and multi-session behavior
document the mirrored global fast path

Validation

npm run lint
npm run compile-tests
npm run unittest — 3,417 passing, 9 pending
npm run compile
npm run smoke-test — 31 passing, 1 pending
focused discovery/interpreter-selection integration suites — 15 passing
npm run e2e-test — 4 passing
npm run integration-test-multiroot — 3 passing, 1 pending
manual Memento/session simulation verified same-workspace cold-global hit, new-workspace cold-global miss, workspace precedence, and serialized tombstones

The full integration run reached 60 passing and 10 pending; its sole failure was the existing environment-creation fixture timing out because project A selects the system manager and enters the interactive Python installer. The cache-relevant integration suites passed separately.

Fixes #1581

Mirror the global system Python selection into workspace state so the same remote workspace can use its persisted fast path when global state is cold. Version mirrored entries and tombstones to preserve workspace-first behavior across partial storage failures, serialize mutations, and invalidate only definitively missing paths. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: 0c45696e-17ec-4b65-9e06-21ea196234d6

Bill Schnurr (bschnurr) · 2026-10-23T20:19:14Z

🔒 Automated review in progress — Bill Schnurr (@bschnurr) is auto-reviewing this PR.

Copilot

🟡 Changes recommended

A partial workspace tombstone failure can resurrect a cleared interpreter after global state is reset or replaced.

1 open issue

Avoid resurrecting cleared workspace entries after partial reset · New

What changed in this PR

This PR improves the system Python startup cache for remote workspaces by mirroring global selections into workspace state, allowing reuse when global state becomes cold.

Changes:

Adds workspace-first lookup, revisioned entries, tombstones, and serialized cache mutations.
Invalidates definitively missing global paths and makes persistent-state clears recover after failures.
Adds cache and failure-recovery tests and updates startup-flow documentation.

File	Description
`src/test/managers/fastPath.get.unit.test.ts`	Tests system-manager stale-path invalidation.
`src/test/managers/common/fastPath.unit.test.ts`	Tests invalidation and transient-failure behavior.
`src/test/managers/builtin/sysPythonManager.pymanager.unit.test.ts`	Tests persisted global-selection reset.
`src/test/managers/builtin/cache.systemEnvGlobal.unit.test.ts`	Covers mirrored persistence, partial failures, and concurrent updates.
`src/test/common/persistentState.unit.test.ts`	Tests recovery and operation blocking during failed clears.
`src/managers/common/fastPath.ts`	Adds optional stale global-path invalidation.
`src/managers/builtin/sysPythonManager.ts`	Connects invalidation and persists selection resets.
`src/managers/builtin/cache.ts`	Implements mirrored, revisioned global-selection persistence.
`src/common/persistentState.ts`	Waits for all deletions and releases blocked operations after failure.
`docs/startup-flow.md`	Documents the mirrored global fast path.

_{Review effort: Balanced}

Bill Schnurr (bschnurr) · 2026-10-23T20:31:05Z

+        return globalSelection.path;
+    }
+    if (hasStoredGlobalSelection(workspace.selection)) {
+        return getStoredGlobalSelectionPath(workspace.selection);


Issue · Please address or respond

📍 src/managers/builtin/cache.ts:190
After caching A, a reset whose workspace payload write fails leaves A behind a newer revision marker; reopening with cold global state then returns A here, resurrecting the cleared selection (runtime-verified by the Skeptic). Treat a known revision mismatch without matching recovery data as a cache miss, and cover reset followed by cold-global reopening.

[unverified]

Bill Schnurr (bschnurr) · 2026-10-23T20:31:10Z

+        await Promise.all([
+            runCacheOperation('update', 'workspaceState', async () => {
+                const state = workspaceState ?? (await getWorkspacePersistentState());
+                await state.set(SYSTEM_GLOBAL_KEY, selection);


Issue · Please address or respond

📍 src/managers/builtin/cache.ts:234
If workspace storage rejects both the marker and payload writes while global state successfully saves B, the old workspace A and marker still agree, so reads keep returning A even across reloads (runtime-verified by both the Advocate and Skeptic). Make successful global writes reconcilable after failed mirror preparation, including across reloads, and cover a whole-layer workspace write failure.

[unverified]

Bill Schnurr (bschnurr) · 2026-10-23T20:31:15Z

Result: 🔴 could-not-verify

Verification details

Verification: The relevant tests could not be fully run in the isolated environment; this review is not fully verified.

Details: Verification could not complete: timeout must be None or at least 2073600 seconds (24 days); shorter completion deadlines are unsupported.

Test runs: none recorded.

Treat a revision marker without a matching completed entry as a cache miss so an older workspace value cannot reappear after a partial clear and cold global state. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: 0c45696e-17ec-4b65-9e06-21ea196234d6

Copilot

🟡 Changes recommended

A failed revision-marker write can make successfully saved selections unreadable, causing reload to choose the default interpreter.

1 open issue

Reconcile failed revision-marker updates with selection writes · New

1 resolved since last review

Avoid resurrecting cleared workspace entries after partial reset

_{Review effort: Balanced}

+            await workspaceState.set(SYSTEM_GLOBAL_REVISION_KEY, revision);
+        } catch (error) {
+            traceError('Failed to prepare workspaceState system Python cache update:', error);
+        }


Bill Schnurr (bschnurr) · 2026-10-23T20:44:47Z

Result: 🔴 could-not-verify

Verification details

Verification: The relevant tests could not be fully run in the isolated environment; this review is not fully verified.

Details: Verification could not complete: timeout must be None or at least 2073600 seconds (24 days); shorter completion deadlines are unsupported.

Test runs: none recorded.

Stella Huang (StellaHuang95) added the bug Issue identified by VS Code Team member as probable bug label Oct 23, 2026

Stella Huang (StellaHuang95) requested a balanced review from Copilot October 23, 2026 20:15

Copilot started reviewing on behalf of Stella Huang (StellaHuang95) October 23, 2026 20:15

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Copilot AI reviewed Oct 23, 2026

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Comment thread src/managers/builtin/cache.ts Outdated

Bill Schnurr (bschnurr) reviewed Oct 23, 2026

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Bill Schnurr (bschnurr) added the review-auto:changes-requested Automated review: posted blocking findings to address. label Oct 23, 2026

Stella Huang (StellaHuang95) requested a balanced review from Copilot October 23, 2026 20:33

Copilot started reviewing on behalf of Stella Huang (StellaHuang95) October 23, 2026 20:34

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Copilot AI reviewed Oct 23, 2026

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Comment thread src/managers/builtin/cache.ts

Comment on lines +232 to +235

await workspaceState.set(SYSTEM_GLOBAL_REVISION_KEY, revision);

} catch (error) {

traceError('Failed to prepare workspaceState system Python cache update:', error);

}

Stella Huang (StellaHuang95) closed this Oct 23, 2026

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Fix cross-session system Python cache misses on remotes - #1951

Fix cross-session system Python cache misses on remotes#1951
Stella Huang (StellaHuang95) wants to merge 2 commits into
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Stella Huang (StellaHuang95) commented Oct 23, 2026 •

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