doobidoo/mcp-memory-service v8.13.1

v8.13.1: Critical Concurrent Access Bugfix

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v8.13.1: Critical Concurrent Access Bugfix

This release fixes a critical regression that prevented MCP memory tools from working while the HTTP server is running.

Problem

Users reported MCP memory tools completely non-functional with error:

sqlite3.OperationalError: database is locked

Impact: Any user running both MCP and HTTP servers experienced total MCP tool failure.

User feedback: "this worked before without any flaws"

Root Causes

1. Connection Timeout Misconfiguration (sqlite_vec.py:329)

   • Used default 5-second timeout, then tried to apply PRAGMA busy_timeout=15000
   • SQLite only respects timeout passed to connect(), ignores pragma applied afterward
   • MCP server timed out before it could set the higher timeout

2. Concurrent DDL Operations (sqlite_vec.py:467-476)

   • Both servers attempted CREATE TABLE, CREATE INDEX simultaneously
   • Even with WAL mode, DDL requires brief exclusive locks
   • No detection of already-initialized database before running DDL

Fixes

Fix #1: Parse timeout from environment BEFORE opening connection (lines 291-326)

• Extract busy_timeout from MCP_MEMORY_SQLITE_PRAGMAS environment variable
• Convert from milliseconds to seconds (15000ms → 15.0s)
• Pass to sqlite3.connect(path, timeout=15.0) for immediate effect
• Allows MCP server to wait up to 15 seconds for HTTP server

Fix #2: Detect initialized database and skip DDL (lines 355-373)

• Check if memories and memory_embeddings tables exist after loading extension
• If tables exist, just load embedding model and mark as initialized
• Prevents "database is locked" errors from concurrent CREATE TABLE/INDEX

Test Validation

✅ MCP health check: healthy with 1857 memories while HTTP server running
✅ Log evidence: "Database already initialized by another process, skipping DDL operations"
✅ Restored pre-v8.9.0 concurrent access behavior

Affected Versions

• Bug introduced: v8.9.0 (database lock prevention pragmas)
• Fixed in: v8.13.1

Files Changed

• src/mcp_memory_service/__init__.py (version bump)
• pyproject.toml (version bump)
• uv.lock (dependency update)
• CHANGELOG.md (release notes)
• src/mcp_memory_service/storage/sqlite_vec.py (concurrent access fixes)

For full details, see CHANGELOG.md

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