fweinberger/align shutdown with spec #1091
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The stdio cleanup was hanging indefinitely when processes ignored termination signals or took too long to exit. This caused the MCP client to freeze during shutdown, especially with servers that don't handle SIGTERM properly. The fix introduces a 2-second timeout for process termination. If a process doesn't exit gracefully within this window, it's forcefully killed. This ensures the client always completes cleanup in bounded time while still giving well-behaved servers a chance to exit cleanly. This resolves hanging issues reported when MCP servers ignore standard termination signals or perform lengthy cleanup operations. Also adds regression tests for #559. resolves #555 Co-authored-by: Cristian Pufu <[email protected]>
The MCP specification recommends closing stdin first to allow servers to exit gracefully before resorting to signals. This approach gives well-behaved servers the opportunity to detect stdin closure and perform clean shutdown without forceful termination. The shutdown sequence now follows a graceful escalation path: first closing stdin and waiting 2 seconds for voluntary exit, then sending SIGTERM if needed, and finally using SIGKILL as a last resort. This minimizes the risk of data loss or corruption while ensuring cleanup always completes. This unified approach works consistently across all platforms and improves compatibility with MCP servers that monitor stdin for lifecycle management. resolves #765 Co-authored-by: davenpi <[email protected]>
This restores the pre-#596 behavior where anyio.open_process is tried first, falling back to subprocess.Popen only when necessary (e.g., when using SelectorEventLoop on Windows). The approach: 1. Try anyio.open_process with CREATE_NO_WINDOW flag 2. If NotImplementedError, fall back to subprocess.Popen wrapper 3. If other exception, retry anyio.open_process without flags Also refactored to extract the fallback logic into a separate _create_windows_fallback_process function for better code organization.
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