[Pedro Henrique Penna (ppenna)]

Replaces #586 by Jay (@jay23606), whose commits are carried here unchanged (head 756f215b2). It is opened from a microsoft/nvx branch so that CI runs on a stable head: automated rebases of the original kept superseding its runs.

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Fixes #503 (executor close blocks on inherited stdout).

This replaces #532, which was closed. This branch is a single commit on current dev, with no merge commits.

Summary

• ExecutorClient.close() closed the buffered stdout stream after the wrapper exited. If a child it started still held stdout, the protocol reader was blocked in readline and held that stream's lock, so close() waited until the child exited (about 20 seconds in the reproduction).
• close() now joins the reader with its existing timeout first. If the reader is still blocked, stdout is not closed, and close() raises executor output is still held open by a surviving process. Otherwise stdout closes as before. The reader is a daemon thread and ends when the surviving process exits.
• Known limit: the surviving child is not terminated. Containing it (for example with a Windows job object) is a separate change.

Test

• ExecutorCloseTests.test_close_is_bounded_when_a_surviving_child_holds_executor_stdout runs a real wrapper that exits after starting a child that inherits stdout. Before the change, close() blocked about 20 seconds and returned without error. After the change it raises within the bound. The test kills the surviving child in a finally block.
• python -B -m unittest test_adversarial: 71 tests, OK (6 skipped, as before).
• ruff check and ruff format --check are clean for both files.
• Not run: the full nvx.py verify, which needs the OpenVMM submodule, and hardware-backed campaigns.

🤖 Generated with Claude Code

[Copilot]

🟢 Approval recommended

The focused changes address the blocking cleanup path with regression coverage and no identified blocking issues.

No open issues 🎉

What changed in this PR

Fixes #503 by keeping executor cleanup bounded when a surviving child holds stdout open.

Changes:

• Moves stdout closure to the reader thread and reports when bounded cleanup leaves it running.
• Discards output received after the reader is abandoned.
• Adds regression coverage for bounded close, stream closure, and discarded output.

File	Description
scripts/​test_adversarial.py	Adds executor cleanup and reader regression tests.
scripts/​nvx_tools/​adversarial.py	Implements reader-owned stdout closure and bounded cleanup.

_{Review effort: Balanced}