bpo-35300: Add usage note to the lru_cache() docs (GH-10707) (GH-10708)
diff --git a/Doc/library/functools.rst b/Doc/library/functools.rst
index 8924593..d19373b 100644
--- a/Doc/library/functools.rst
+++ b/Doc/library/functools.rst
@@ -85,6 +85,11 @@
The cache's size limit assures that the cache does not grow without bound on
long-running processes such as web servers.
+ In general, the LRU cache should only be used when you want to reuse
+ previously computed values. Accordingly, it doesn't make sense to cache
+ functions with side-effects, functions that need to create distinct mutable
+ objects on each call, or impure functions such as time() or random().
+
Example of an LRU cache for static web content::
@lru_cache(maxsize=32)