Implement concurrent safety patterns

When designing concurrent systems, implement comprehensive safety patterns that handle resource lifecycle management, race conditions, and proper cleanup mechanisms. This includes setting resource limits to prevent exhaustion, implementing timeout-based cleanup for idle resources, and handling database race conditions with proper rollback and retry logic.

Key patterns to implement:

1. Resource Lifecycle Management: Use structured cleanup with limits and timeouts

   class ResourceManager:
    def __init__(self):
        self.resources_by_key = {}  # Group resources by identity
        self._cleanup_task = asyncio.create_task(self._periodic_cleanup())
       
    async def _periodic_cleanup(self):
        """Periodically clean up idle resources."""
        while True:
            await asyncio.sleep(CLEANUP_INTERVAL)
            await self._cleanup_idle_resources()
       
    async def get_resource(self, key, params):
        # Check limits before creating new resources
        if len(self.resources_by_key.get(key, {})) >= MAX_RESOURCES_PER_KEY:
            # Remove oldest resource
            await self._cleanup_oldest_resource(key)
   

2. Race Condition Handling: Implement proper exception handling with rollback and retry

   async def create_resource(name, session):
    try:
        # Check if resource exists
        existing = await get_resource_by_name(name, session)
        if existing:
            return existing
           
        # Create new resource
        resource = Resource(name=name)
        session.add(resource)
        await session.commit()
        return resource
    except IntegrityError:
        # Handle race condition - another worker created it
        await session.rollback()
        existing = await get_resource_by_name(name, session)
        if existing:
            return existing
        raise  # Re-raise if no resource found after rollback
   

3. Test Concurrent Scenarios: Use asyncio.gather() to test real concurrent behavior

   @pytest.mark.asyncio
   async def test_concurrent_resource_creation():
    """Test multiple concurrent calls handle race conditions properly."""
    tasks = [
        create_resource("shared_name", session1),
        create_resource("shared_name", session2)
    ]
    results = await asyncio.gather(*tasks, return_exceptions=True)
    # Verify both succeed or handle conflicts gracefully
   

Always consider the impact of automatic resource cleanup on user experience and provide clear boundaries for resource limits to prevent unexpected behavior disruptions.