testing: Fix POSIX result pipe EOF and descriptor ownership - #26082
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Pull request overview
This PR fixes a POSIX FIFO EOF detection gap in the test result named-pipe reader that caused test runs to regularly wait for the 5s RESULT_PIPE_DRAIN_TIMEOUT_MS fallback after the Python subprocess exited. It replaces the FIFO net.Socket reader with a direct FD reader that can reliably settle onClose on writer disconnect, and updates adapters to explicitly dispose result-pipe resources after the drain/timeout window.
Changes:
- Replace the POSIX FIFO reader implementation to detect writer EOF and fire close reliably (
FifoMessageReader). - Change
startRunResultNamedPipe()to return an owned{ name, dispose }handle and have pytest/unittest execution adapters dispose it after drain/timeout. - Update/extend unit tests to cover POSIX FIFO reader behavior and adapter disposal during cancellation.
Show a summary per file
| File | Description |
|---|---|
| src/client/common/pipes/namedPipes.ts | Adds a POSIX FIFO FD-based message reader and wires it into createReaderPipe(). |
| src/client/testing/testController/common/utils.ts | Changes startRunResultNamedPipe() to return an owned handle with a dispose() method. |
| src/client/testing/testController/pytest/pytestExecutionAdapter.ts | Uses resultPipe.name and disposes the result pipe after drain/timeout. |
| src/client/testing/testController/unittest/testExecutionAdapter.ts | Uses resultPipe.name and disposes the result pipe after drain/timeout. |
| src/test/common/pipes/namedPipes.unit.test.ts | Adds POSIX FIFO tests for buffered payloads, empty writer, and cancellation close. |
| src/test/testing/testController/pytest/pytestExecutionAdapter.unit.test.ts | Updates stubs to match the new { name, dispose } result-pipe return type. |
| src/test/testing/testController/unittest/testExecutionAdapter.unit.test.ts | Updates stubs to match the new { name, dispose } result-pipe return type. |
| src/test/testing/testController/testCancellationRunAdapters.unit.test.ts | Asserts the adapter disposes the result-pipe handle during cancellation flows. |
Review details
- Files reviewed: 8/8 changed files
- Comments generated: 1
- Review effort level: Lite
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| if (bytesRead > 0) { | ||
| this.hasReadData = true; | ||
| this.stream.write(Buffer.from(this.buffer.subarray(0, bytesRead))); | ||
| continue; | ||
| } |
Eleanor Boyd (eleanorjboyd)
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This was referenced Sep 29, 2026
[Linux] Extension host crashes because POSIX test-result FIFO file descriptor is closed twice
#26173
Open
Drain nonblocking FIFO readers to EOF and explicitly dispose result pipes after the fallback timeout. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Use the disposable result pipe handle returned by the updated test utility. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Honor parser backpressure and signal pipe completion when test subprocess work ends so empty or failed writers cannot leave polling readers behind. Add focused coverage for backpressure and empty-writer cleanup.\n\nCo-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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Eleanor Boyd (eleanorjboyd)
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Eleanor Boyd (eleanorjboyd)
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September 29, 2026 20:33
Eleanor Boyd (eleanorjboyd)
marked this pull request as draft
September 29, 2026 20:44
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Summary
net.Socketreader with a directly owned nonblocking reader that detects writer disconnect and closes its descriptor exactly onceWhy
The previous implementation gave the same FIFO descriptor to both
net.Socketand an explicitfs.close(fd)callback. On Linux, the socket could close the descriptor, the OS could reuse that descriptor number, and the asynchronous second close could close an unrelated descriptor and abort the extension host.The socket reader also did not surface FIFO EOF, causing completed test runs to wait for the five-second drain fallback. The new reader owns the descriptor for its full lifecycle, drains to EOF, observes backpressure, and receives explicit completion signals from test adapters so short empty writers or failed subprocess launches do not leave polling readers behind.
Validation
npx gulp prePublishNonBundleFixes #26071
Fixes #26173