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Comment by spinlock | Hacker News Reader

What projects are people using Redis for? I'd love to know how others are using Lua or plan to use the new module system specifically.

We're using redis as a queue (Sidekiq) and also to store the index.html page for our SPA. We have an "active" key in redis and its value is the key for the current index.html. This let's us push new versions of our app into redis (each generation of our asset files has a unique name so a new index.html gives you a new version of the SPA). We can then add a get param to our URL and pull a specific version of the index.html out of redis. Once we've smoke tested, we update our "current" value to point to the new index.html and, boom, zero downtime deploys.

What's your story?

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At my previous job (industry-specific CMS supporting many websites) we used redis simply as a distributed cache to support our this application since it was deployed to a load-balanced webfarm. The CMS platform we were building off of had its own webfarm-cache solution but we found it to result in a lot of inter-server communication which only hurt our load issues even more. Redis came in as a very simple out-of-the-box solution to that problem and performance was improved tremendously. I abstracted the client in case we had to switch to Memcached etc but Redis really just knocked our socks off and the documentation was a godsend. I left before adding Redis Cluster to our stack unfortunately but I did get to experiment with that and it also looked very promising. Having used it I strongly recommend my colleagues look into it anytime caching comes up.

We use Redis as a record level distributed lock on top of pub/sub and a cache and a queue. We also take advantage of expiring keys to detect if users are connected or have activity. We used to use it a session store but switched to encrypted cookies. I know some have used it as a semaphore as well.

What did the semaphore usage look like? Did it use pub/sub or something else?

Also what encryption algorithm are you using on your cookies. I ask because certain algorithms produce malleable ciphertexts, which could potentially be a huge vulnerability.

I use redis for a multiplayer mobile game. Stores user details, game scores, global leaderboard and randomly generated game data that exists for the time of a single game.

The Internet Archive uses Redis for a lot of things. We use it as a read-only cache for all of the metadata about our "items" (books/videos/etc). We use it to store information about "save page now" pages in the Wayback Machine, so that you can immediately replay a saved page. (The main Wayback index is 60 TBytes; not in Redis today, maybe someday.)

There was a nice talk given by someone at Twitter about how they use Redis, including their shortcomings (which, interestingly, they had to solve by forking Redis and fiddling with the internals; maybe modules will help them get back closer to upstream ?)

Here's the highscalability writeup: http://highscalability.com/blog/2014/9/8/how-twitter-uses-re...

I started playing with Modules & LuaJIT, mostly a proof of concept of what can be done. Much more to do, but my goal is to replace my existing Lua/Redis scripts with this.

https://github.com/neomantra/redis-mod_luajit

We use redis as a cache to store oauth tokens, and expire then automatically.

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