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Select the correct synchronization mechanism based on your execution context and avoid unnecessary synchronization overhead. In async contexts with coroutines, locks are often unnecessary since coroutines run cooperatively in a single thread. Use asyncio.Lock() for async contexts and threading.Lock() for multi-threaded scenarios. When bridging sync and async code with threads, ensure proper context variable propagation and use daemon threads for background tasks.

Key guidelines:

• Async contexts: Coroutines run cooperatively, so locks are usually unnecessary unless coordinating with external threads
• Mixed contexts: Use asyncio.Lock() when coordinating async tasks, threading.Lock() for thread coordination
• Thread creation: Use daemon threads for background tasks and ensure proper exception propagation
• Context variables: Copy context when creating threads to maintain variable scope

Example of proper lock selection:

# Async context - lock usually unnecessary
async def process_nodes_async(self, nodes):
    # Coroutines run cooperatively, no race conditions
    for node in nodes:
        self.state.completed_nodes.add(node)

# Mixed async/thread context - use asyncio.Lock
class GraphExecutor:
    def __init__(self):
        self._lock = asyncio.Lock()  # For async task coordination
    
    async def execute_parallel(self, nodes):
        async with self._lock:  # Only if truly needed
            # Critical section
            pass

# Thread context - use threading.Lock  
class FileManager:
    def __init__(self):
        self._lock = threading.RLock()  # For thread coordination
    
    def write_file(self, data):
        with self._lock:
            # Thread-safe file operations
            pass

Before adding synchronization, verify you actually have a race condition. Many async operations don’t require explicit locking due to the cooperative nature of coroutines.

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