Bidding needed a live blacklist. 50k req/s. Using Redis Worked fine but it was another service to maintain/monitor and another potential failure point. Tried an in-memory map. Faster, but died on every deploy. Cache gone.

Then we tried /dev/shm. Just wrote temp files there. RAM speed. Survives restarts because the OS holds it since it's temp it won't survive os restart but in our use case it's doesn't; matter

os.CreateTemp("/dev/shm", "blacklist-*")