Memory-Efficient Caching with WeakRef

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Memory-Efficient Caching with WeakRef

A WeakValueDictionary holds 'weak' references to its values. If an object is no longer referenced anywhere else in the program, the garbage collector can delete it even if it is still a value in the dictionary, automatically preventing memory leaks in caches.

snippet.py
python
import weakref
 
class DataBlob:
    def __init__(self, data): self.data = data
 
cache = weakref.WeakValueDictionary()
blob = DataBlob("heavy-data")
cache["key"] = blob
 
print("Cached:", "key" in cache)
del blob
print("After del:", "key" in cache)

Breakdown

cache = weakref.WeakValueDictionary()

Creates a dictionary where values are garbage-collected if no strong references exist.

del blob

Removes the only strong reference, triggering immediate cleanup from the cache.

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Memory-Efficient Caching with WeakRef

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