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# Daemon Mode
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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.
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## Capabilities
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### Daemon Operations
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```python { .api }
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# Available through dmypy command-line tool
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# Start daemon: dmypy daemon
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# Check files: dmypy check [files...]
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# Stop daemon: dmypy stop
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# Restart daemon: dmypy restart
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# Get status: dmypy status
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```
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#### Performance Benefits
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- **First run**: Same speed as regular mypy
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- **Subsequent runs**: 10-50x faster for large codebases
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- **Incremental analysis**: Only re-analyzes changed files and dependencies
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- **Memory persistence**: Keeps type information in memory between runs
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### Integration Usage
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```python
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from mypy import api
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# Use daemon through programmatic API (not thread-safe)
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result = api.run_dmypy(['check', 'myfile.py'])
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stdout, stderr, exit_code = result
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# Daemon management
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api.run_dmypy(['daemon'])  # Start daemon
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api.run_dmypy(['stop'])    # Stop daemon
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```
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For detailed daemon usage patterns, see [Command Line Tools](./command-line-tools.md) and [Programmatic API](./programmatic-api.md) documentation.