Daemon Mode

High-performance daemon mode for faster incremental type checking in development environments. The dmypy daemon provides significant performance improvements for repeated type checking of large codebases.

Capabilities

Daemon Operations

# Available through dmypy command-line tool
# Start daemon: dmypy daemon
# Check files: dmypy check [files...]
# Stop daemon: dmypy stop
# Restart daemon: dmypy restart
# Get status: dmypy status

Performance Benefits

• First run: Same speed as regular mypy
• Subsequent runs: 10-50x faster for large codebases
• Incremental analysis: Only re-analyzes changed files and dependencies
• Memory persistence: Keeps type information in memory between runs

Integration Usage

from mypy import api

# Use daemon through programmatic API (not thread-safe)
result = api.run_dmypy(['check', 'myfile.py'])
stdout, stderr, exit_code = result

# Daemon management
api.run_dmypy(['daemon'])  # Start daemon
api.run_dmypy(['stop'])    # Stop daemon

For detailed daemon usage patterns, see Command Line Tools and Programmatic API documentation.