On first invocation of the Firebase function I create a mysql connection pool (which is expensive) and store it in global scope. This works fine as long as there is a single instance serving requests. Assuming multiple functions instances can exist under load, what's a good practice to prevent numerous such pools from getting created?

CodePudding user response：

There is a specific section in the Cloud Functions documentation: "Use global variables to reuse objects in future invocations".

There is no guarantee that the state of a Cloud Function will be preserved for future invocations. However, Cloud Functions often recycles the execution environment of a previous invocation. If you declare a variable in global scope, its value can be reused in subsequent invocations without having to be recomputed.

This way you can cache objects that may be expensive to recreate on each function invocation.

CodePudding user response：

Cloud functions scale up to 1,000 instances per region.

SQL connections scale up to 32,000 .

Practically speaking, you're not going to run into upper limits on your db connection(s).