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Fix: Replace threading.Lock with anyio.Lock for Ray deployment compatibility #1151

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only-weng
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Replace threading.Lock with anyio.Lock for Ray deployment compatibility

Motivation and Context

When deploying StreamableHTTP services with Ray, we encountered serialization issues because threading.Lock objects cannot be pickled/serialized. This causes deployment failures when Ray tries to serialize the session manager objects across worker processes.

Types of changes

  • Bug fix (non-breaking change which fixes an issue)
  • New feature (non-breaking change which adds functionality)
  • Breaking change (fix or feature that would cause existing functionality to change)
  • Documentation update

Checklist

  • I have read the MCP Documentation
  • My code follows the repository's style guidelines
  • New and existing tests pass locally
  • I have added appropriate error handling
  • I have added or updated documentation as needed

Additional context

…ibility

- Replace threading.Lock() with anyio.Lock() in StreamableHTTPSessionManager
- This resolves serialization issues when deploying StreamableHTTP services with Ray
- threading.Lock objects cannot be pickled/serialized, causing deployment failures
- anyio.Lock provides equivalent functionality while being fully serializable
- Update lock usage from 'with' to 'async with' for proper async context
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@ihrpr ihrpr left a comment

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Thank you!

@ihrpr ihrpr merged commit c260e29 into modelcontextprotocol:main Jul 21, 2025
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2 participants