--- title: "How Redis Caps Its Memory Usage | Redis Internals" url: https://daily.dev/posts/how-redis-caps-its-memory-usage-redis-internals-ovm1kfcj9 source_url: https://www.youtube.com/watch?v=xNfoeZuK3Mc type: video:youtube source: "Asli Engineering by Arpit Bhayani" published: 2026-05-31T07:49:14.435Z updated: 2026-05-31T09:16:44.962Z tags: ["backend", "redis"] reading_time: 13 upvotes: 0 comments: 0 language: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # How Redis Caps Its Memory Usage | Redis Internals **[Asli Engineering by Arpit Bhayani](https://daily.dev/sources/asli-engineering)** · 13 min read · 0 upvotes · 0 comments ## Summary A deep dive into Redis internals explaining how Redis tracks and caps memory usage. Rather than limiting by key count, Redis wraps standard malloc with a custom zmalloc implementation that atomically tracks total allocated bytes via a global counter. This allows Redis to know its exact memory consumption at any moment without expensive system calls. The zmalloc layer deliberately does not enforce limits itself — it only tracks usage. Enforcement happens separately in evict.c, which loops and evicts keys until used memory drops below the configured maxmemory threshold. The post also briefly discusses why a Go reimplementation caps by key count instead, since Go lacks easy manual memory management hooks. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Internals for Interns](https://daily.dev/posts/internals-for-interns-fg0xibngw) · Hacker News · 0 upvotes · 0 comments --- Tags: [#backend](https://daily.dev/tags/backend), [#redis](https://daily.dev/tags/redis) [View this post on daily.dev](https://daily.dev/posts/how-redis-caps-its-memory-usage-redis-internals-ovm1kfcj9)