Add regression test for issue #1027 #1069
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When terminating MCP servers, child processes were being orphaned because only the parent process was killed. This caused resource leaks and prevented proper cleanup, especially with tools like npx that spawn child processes for the actual server implementation. This was happening on both POSIX and Windows systems - however because of implementation details, resolving this is non-trivial and requires introducing psutil to introduce cross-platform utilities for dealing with children and process trees. This addresses critical issues where MCP servers using process spawning tools would leave zombie processes running after client shutdown. resolves #850 resolves #729 Co-authored-by: jingx8885 <[email protected]> Co-authored-by: Surya Prakash Susarla <[email protected]>
This test shows that MCP server cleanup code in lifespan doesn't run when the process is terminated, but does run when stdin is closed first (as implemented in PR #1044). The test includes: - Demonstration of current broken behavior (cleanup doesn't run) - Verification that stdin closure allows graceful shutdown - Windows-specific ResourceWarning handling - Detailed documentation of the issue and solution Github-Issue:#1027
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Motivation and Context
Issue #1027 reports that MCP server cleanup code (after yield in lifespan) is unreachable when the process is terminated. This PR adds tests that:
How Has This Been Tested?
Added two tests in
test_1027_win_unreachable_cleanup.py:test_lifespan_cleanup_executed- Shows cleanup doesn't run with current termination (xfails)test_stdin_close_triggers_cleanup- Shows cleanup works when stdin is closed first (passes)Tested on both macOS and Windows.
When run with PR #1044's changes, both tests pass.
Breaking Changes
None. Tests only.
Types of changes
Checklist
Additional context