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Duplicated from  akhaliq/Laguna-S-2.1

poolside

/

Laguna-S-2.1

like 26

Running

This cache is meant to be thread-safe and evict least-recently-used entries. It
passes single-threaded tests and passes a load test with 8 threads doing random
gets. In production under heavy concurrent writes it occasionally returns a
value for a key that was never inserted.

Find the bug, explain the exact interleaving that causes it, and give the
minimal fix.

```python
class LRUCache:
    def __init__(self, capacity):
        self.capacity = capacity
        self.data = {}
        self.order = []
        self.lock = threading.Lock()

    def get(self, key):
        with self.lock:
            if key not in self.data:
                return None
            self.order.remove(key)
            self.order.append(key)
            return self.data[key]

    def put(self, key, value):
        with self.lock:
            if key in self.data:
                self.order.remove(key)
            elif len(self.data) >= self.capacity:
                oldest = self.order.pop(0)
                del self.data[oldest]
            self.order.append(key)
        self.data[key] = value

She broke! https://huggingface.co/poolside/Laguna-S-2.1-NVFP4/discussions/16