Summary

Add optional uvloop integration to zarr-python to improve I/O performance for async operations.

Motivation

zarr-python performs many I/O operations, especially when working with remote storage backends (S3, GCS, etc.). uvloop is a fast, drop-in replacement for Python's default asyncio event loop that can provide significant performance improvements for I/O-intensive workloads.

Proposed Solution

• Automatically use uvloop when available and supported (non-Windows platforms)
• Make it configurable via async.use_uvloop config setting
• Add uvloop as an optional dependency: pip install 'zarr[optional]'
• Gracefully fall back to standard asyncio when uvloop is unavailable
• No breaking changes - fully backward compatible

Expected Benefits

• Improved performance for remote storage operations
• Better concurrent I/O handling
• Faster network-bound workloads

Configuration

# Enable (default when available)
zarr.config.set({"async.use_uvloop": True})

# Disable
zarr.config.set({"async.use_uvloop": False})

# Via environment variable
export ZARR_ASYNC__USE_UVLOOP=false

Implementation Notes

• uvloop only works on Unix-like systems (Linux, macOS)
• Automatic fallback on Windows
• Zero configuration required - works out of the box when installed
• uvloop will be an optional dependency

This enhancement would provide measurable performance improvements for users working with remote zarr stores while maintaining full compatibility with existing code.