ab -n 1 -c 1 <request_url>
http://localhost:5000/buy/{productId}
http://localhost:5000/getquantity/{productId}
https://github.com/madelson/DistributedLock
https://www.codemag.com/article/0607081/Database-Concurrency-Conflicts-in-the-Real-World
https://redis.io/topics/distlock
https://github.com/samcook/RedLock.net
https://martin.kleppmann.com/2016/02/08/how-to-do-distributed-locking.html