litellm/AGENTS.md
Cursor Agent d919b1048e fix: reduce memory retention after traffic spikes
Two-pronged fix for the reported memory leak where RSS grows from ~1.9 GiB
to ~3.5 GiB under load (1000-1500 concurrent users) and never returns to
baseline:

1. Logging._cleanup_after_logging(): Clears large payload fields (input,
   original_response, raw_request_typed_dict) and streaming chunk lists from
   the Logging object after all success/failure callbacks have consumed them.
   This prevents per-request data (which can be kilobytes per request) from
   being held in memory by async task references.

2. _periodic_memory_cleanup(): A scheduled background job (every 60s by
   default, configurable via LITELLM_MEMORY_CLEANUP_INTERVAL) that runs
   gc.collect() + malloc_trim(0) on Linux. Python's pymalloc allocator does
   not return freed memory arenas to the OS by default; malloc_trim forces
   glibc to release unused heap pages, allowing RSS to shrink after traffic
   spikes subside.

Together these ensure that:
- Per-request memory is released promptly after logging completes
- The OS reclaims freed heap memory periodically, so RSS drops during idle
  periods instead of staying at the peak level indefinitely

Co-authored-by: Ishaan Jaff <ishaan-jaff@users.noreply.github.com>
2026-02-25 23:05:12 +00:00

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# INSTRUCTIONS FOR LITELLM
This document provides comprehensive instructions for AI agents working in the LiteLLM repository.
## OVERVIEW
LiteLLM is a unified interface for 100+ LLMs that:
- Translates inputs to provider-specific completion, embedding, and image generation endpoints
- Provides consistent OpenAI-format output across all providers
- Includes retry/fallback logic across multiple deployments (Router)
- Offers a proxy server (LLM Gateway) with budgets, rate limits, and authentication
- Supports advanced features like function calling, streaming, caching, and observability
## REPOSITORY STRUCTURE
### Core Components
- `litellm/` - Main library code
- `llms/` - Provider-specific implementations (OpenAI, Anthropic, Azure, etc.)
- `proxy/` - Proxy server implementation (LLM Gateway)
- `router_utils/` - Load balancing and fallback logic
- `types/` - Type definitions and schemas
- `integrations/` - Third-party integrations (observability, caching, etc.)
### Key Directories
- `tests/` - Comprehensive test suites
- `docs/my-website/` - Documentation website
- `ui/litellm-dashboard/` - Admin dashboard UI
- `enterprise/` - Enterprise-specific features
## DEVELOPMENT GUIDELINES
### MAKING CODE CHANGES
1. **Provider Implementations**: When adding/modifying LLM providers:
- Follow existing patterns in `litellm/llms/{provider}/`
- Implement proper transformation classes that inherit from `BaseConfig`
- Support both sync and async operations
- Handle streaming responses appropriately
- Include proper error handling with provider-specific exceptions
2. **Type Safety**:
- Use proper type hints throughout
- Update type definitions in `litellm/types/`
- Ensure compatibility with both Pydantic v1 and v2
3. **Testing**:
- Add tests in appropriate `tests/` subdirectories
- Include both unit tests and integration tests
- Test provider-specific functionality thoroughly
- Consider adding load tests for performance-critical changes
### MAKING CODE CHANGES FOR THE UI (IGNORE FOR BACKEND)
1. **Tremor is DEPRECATED, do not use Tremor components in new features/changes**
- The only exception is the Tremor Table component and its required Tremor Table sub components.
2. **Use Common Components as much as possible**:
- These are usually defined in the `common_components` directory
- Use these components as much as possible and avoid building new components unless needed
3. **Testing**:
- The codebase uses **Vitest** and **React Testing Library**
- **Query Priority Order**: Use query methods in this order: `getByRole`, `getByLabelText`, `getByPlaceholderText`, `getByText`, `getByTestId`
- **Always use `screen`** instead of destructuring from `render()` (e.g., use `screen.getByText()` not `getByText`)
- **Wrap user interactions in `act()`**: Always wrap `fireEvent` calls with `act()` to ensure React state updates are properly handled
- **Use `query` methods for absence checks**: Use `queryBy*` methods (not `getBy*`) when expecting an element to NOT be present
- **Test names must start with "should"**: All test names should follow the pattern `it("should ...")`
- **Mock external dependencies**: Check `setupTests.ts` for global mocks and mock child components/networking calls as needed
- **Structure tests properly**:
- First test should verify the component renders successfully
- Subsequent tests should focus on functionality and user interactions
- Use `waitFor` for async operations that aren't already awaited
- **Avoid using `querySelector`**: Prefer React Testing Library queries over direct DOM manipulation
### IMPORTANT PATTERNS
1. **Function/Tool Calling**:
- LiteLLM standardizes tool calling across providers
- OpenAI format is the standard, with transformations for other providers
- See `litellm/llms/anthropic/chat/transformation.py` for complex tool handling
2. **Streaming**:
- All providers should support streaming where possible
- Use consistent chunk formatting across providers
- Handle both sync and async streaming
3. **Error Handling**:
- Use provider-specific exception classes
- Maintain consistent error formats across providers
- Include proper retry logic and fallback mechanisms
4. **Configuration**:
- Support both environment variables and programmatic configuration
- Use `BaseConfig` classes for provider configurations
- Allow dynamic parameter passing
## PROXY SERVER (LLM GATEWAY)
The proxy server is a critical component that provides:
- Authentication and authorization
- Rate limiting and budget management
- Load balancing across multiple models/deployments
- Observability and logging
- Admin dashboard UI
- Enterprise features
Key files:
- `litellm/proxy/proxy_server.py` - Main server implementation
- `litellm/proxy/auth/` - Authentication logic
- `litellm/proxy/management_endpoints/` - Admin API endpoints
## MCP (MODEL CONTEXT PROTOCOL) SUPPORT
LiteLLM supports MCP for agent workflows:
- MCP server integration for tool calling
- Transformation between OpenAI and MCP tool formats
- Support for external MCP servers (Zapier, Jira, Linear, etc.)
- See `litellm/experimental_mcp_client/` and `litellm/proxy/_experimental/mcp_server/`
## RUNNING SCRIPTS
Use `poetry run python script.py` to run Python scripts in the project environment (for non-test files).
## GITHUB TEMPLATES
When opening issues or pull requests, follow these templates:
### Bug Reports (`.github/ISSUE_TEMPLATE/bug_report.yml`)
- Describe what happened vs. expected behavior
- Include relevant log output
- Specify LiteLLM version
- Indicate if you're part of an ML Ops team (helps with prioritization)
### Feature Requests (`.github/ISSUE_TEMPLATE/feature_request.yml`)
- Clearly describe the feature
- Explain motivation and use case with concrete examples
### Pull Requests (`.github/pull_request_template.md`)
- Add at least 1 test in `tests/litellm/`
- Ensure `make test-unit` passes
## TESTING CONSIDERATIONS
1. **Provider Tests**: Test against real provider APIs when possible
2. **Proxy Tests**: Include authentication, rate limiting, and routing tests
3. **Performance Tests**: Load testing for high-throughput scenarios
4. **Integration Tests**: End-to-end workflows including tool calling
## DOCUMENTATION
- Keep documentation in sync with code changes
- Update provider documentation when adding new providers
- Include code examples for new features
- Update changelog and release notes
## SECURITY CONSIDERATIONS
- Handle API keys securely
- Validate all inputs, especially for proxy endpoints
- Consider rate limiting and abuse prevention
- Follow security best practices for authentication
## ENTERPRISE FEATURES
- Some features are enterprise-only
- Check `enterprise/` directory for enterprise-specific code
- Maintain compatibility between open-source and enterprise versions
## COMMON PITFALLS TO AVOID
1. **Breaking Changes**: LiteLLM has many users - avoid breaking existing APIs
2. **Provider Specifics**: Each provider has unique quirks - handle them properly
3. **Rate Limits**: Respect provider rate limits in tests
4. **Memory Usage**: Be mindful of memory usage in streaming scenarios
5. **Dependencies**: Keep dependencies minimal and well-justified
6. **UI/Backend Contract Mismatch**: When adding a new entity type to the UI, always check whether the backend endpoint accepts a single value or an array. Match the UI control accordingly (single-select vs. multi-select) to avoid silently dropping user selections
7. **Missing Tests for New Entity Types**: When adding a new entity type (e.g., in `EntityUsage`, `UsageViewSelect`), always add corresponding tests in the existing test files and update any icon/component mocks
## HELPFUL RESOURCES
- Main documentation: https://docs.litellm.ai/
- Provider-specific docs in `docs/my-website/docs/providers/`
- Admin UI for testing proxy features
## WHEN IN DOUBT
- Follow existing patterns in the codebase
- Check similar provider implementations
- Ensure comprehensive test coverage
- Update documentation appropriately
- Consider backward compatibility impact
## Cursor Cloud specific instructions
### Environment setup
- Python 3.12 with `poetry install --with dev,proxy-dev --extras proxy`
- Install `psycopg-binary` and `psutil` separately: `poetry run pip install psycopg-binary psutil`
- Lint: `cd litellm && poetry run ruff check .`
- Unit tests: `poetry run pytest tests/test_litellm/ -x -n 4` (see `Makefile` for specific test groups)
- Memory/load tests: `poetry run pytest tests/load_tests/test_linear_memory_growth.py::test_memory_baseline_1k -v` (run individually, not all at once)
### Running the proxy server locally
- `poetry run litellm --model openai/gpt-4o` (requires `OPENAI_API_KEY`)
- Proxy listens on port 4000 by default
- No PostgreSQL or Redis required for basic SDK/proxy testing with mock endpoints
### Memory leak testing
- Existing tests in `tests/load_tests/` use a local mock OpenAI server (no API keys needed)
- `test_linear_memory_growth.py` tests are designed to run **individually** (memory baselines drift when combined)
- `_periodic_memory_cleanup()` in `litellm/proxy/common_utils/memory_utils.py` calls `gc.collect()` + `malloc_trim()` on Linux to return freed memory to the OS
- `LITELLM_MEMORY_CLEANUP_INTERVAL` env var controls cleanup frequency (default 60s)
- `PYTHON_GC_THRESHOLD` env var configures GC thresholds (format: `gen0,gen1,gen2`)