Ozan Tezcan 9ebf80a28c Fix memory leak of jemalloc tcache on function flush command (#13661) ...

Starting from https://github.com/redis/redis/pull/13133, we allocate a
jemalloc thread cache and use it for lua vm.
On certain cases, like `script flush` or `function flush` command, we
free the existing thread cache and create a new one.

Though, for `function flush`, we were not actually destroying the
existing thread cache itself. Each call creates a new thread cache on
jemalloc and we leak the previous thread cache instances. Jemalloc
allows maximum 4096 thread cache instances. If we reach this limit,
Redis prints "Failed creating the lua jemalloc tcache" log and abort.

There are other cases that can cause this memory leak, including
replication scenarios when emptyData() is called.

The implication is that it looks like redis `used_memory` is low, but
`allocator_allocated` and RSS remain high.

Co-authored-by: debing.sun <debing.sun@redis.com>

2024-11-21 14:12:58 +03:00

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