Concurrency:
Multiple threads operate on the same resources to ensure thread safety and rational use of resources
High concurrency:
The service can handle many requests at the same time (such as 12306 ticket grabbing, Tmall Double 11 spike activity, which will cause the system to perform a large number of operations in a short period of time, such as resource requests, database access), improve program performance ( If high concurrency is not handled well, it will not only lead to poor user experience, but also may cause server downtime, memory leaks and other problems)
