We recently had an issue where redis would needlessly free keys when at maxmemory while under heavy client load. This turned out to be because on each loop through aeMain, redis would handle many pending client GET requests with large returned value sizes. To get back below maxmemory, redis would thus free keys after each client request, even though the buffers were tmporary.

We fixed this by calling handleClientsWithPendingWrites() in processInputBuffer() to prevent this "reply backlog". Another solution would be to not include pending client output buffer memory in freeMemoryGetNotCountedMemory(), perhaps.

Curious if others have an opinion on this. Happy to submit a patch if people feel this is an actual bug.