What is cache and what risk can it add to the system?

Cache is a mechanism for temporarily storing data or computation results to speed up access to them during repeated requests. In programming and systems, cache helps reduce delays and load on data sources (such as databases or external services).

Risks associated with cache:

• Stale data: if the cache is not updated in a timely manner, the system may operate with incorrect information.
• Synchronization complexity: maintaining cache consistency becomes more difficult in distributed systems.
• Memory: cache consumes additional memory, which can lead to exhaustion.
• Caching logic errors: improper cache management can cause bugs and unexpected behavior.

Example in Python using a decorator for caching function results:

from functools import lru_cache

@lru_cache(maxsize=128)
def fibonacci(n):
    if n < 2:
        return n
    return fibonacci(n-1) + fibonacci(n-2)

print(fibonacci(10))  # Fast repeated call thanks to cache