Fix specialization double-start race - #841
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Swapnil Nagar (swapnil-nagar) wants to merge 1 commit into
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Preserve initialized app state when worker init and environment reload target the same directory, and exclude node_modules from entry-point globs. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: eff15798-612c-4121-a6d4-ec5e093bff1f
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Swapnil Nagar (swapnil-nagar)
August 24, 2026 17:12
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Pull request overview
Fixes duplicate app startup during specialization while excluding dependency files from entry-point globbing.
Changes:
- Preserves app registrations for same-directory reloads.
- Excludes
node_modulesfrom entry-point globs. - Adds specialization and glob-exclusion tests.
Reviewed changes
Copilot reviewed 6 out of 6 changed files in this pull request and generated 1 comment.
Show a summary per file
| File | Description |
|---|---|
src/eventHandlers/FunctionEnvironmentReloadHandler.ts |
Preserves same-directory app state. |
src/startApp.ts |
Excludes dependency files from globbing. |
test/eventHandlers/FunctionEnvironmentReloadHandler.test.ts |
Tests specialization behavior. |
test/eventHandlers/WorkerInitHandler.test.ts |
Tests glob exclusion. |
test/eventHandlers/testApp/src/registerV4Function.js |
Adds v4 registration fixture. |
test/eventHandlers/testApp/src/dependencyEntry.js |
Adds glob-matching fixture. |
Suppressed comments (1)
src/eventHandlers/FunctionEnvironmentReloadHandler.ts:80
- For this same-directory specialization path, all entry-point code and
appStarthooks have already run before lines 67–69 install the specialized environment. SkippingstartApp()therefore leaves any configuration captured fromprocess.envinitialized with placeholder values, even though the reload response succeeds. The lifecycle needs to defer the first app start until specialization, or perform a cache-safe restart that preserves/rebuilds registrations while running startup against the new environment.
if (!functionAppDirectoryUnchanged) {
await startApp(msg.functionAppDirectory);
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Comment on lines
+30
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| const functionAppDirectoryUnchanged = | ||
| !!worker.app.functionAppDirectory && | ||
| !!msg.functionAppDirectory && | ||
| isPathEqual(worker.app.functionAppDirectory, msg.functionAppDirectory); |
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A specialization race can send
WorkerInitRequestandFunctionEnvironmentReloadRequestfor the same real app. Resetting app state before the second startup loses v4 registrations, while Node's module cache prevents their side effects from running again, leaving the worker on the default v3 model with no loadable functions.This change preserves the initialized
AppContextwhen both requests target the same directory while still applying the specialized environment and working directory. Normal placeholder specialization continues to reset and start the real app when its directory differs. Entry-point globbing also excludesnode_modulesso broadmainpatterns cannot load dependencies as application entry points.Tests cover v4 model and function-registration preservation across the duplicate lifecycle sequence, normal placeholder specialization, and
node_modulesglob exclusion.Fixes #838