knex oracle dialect sets UV_THREADPOOL_SIZE without knowing the effect

[tsondergaard]

lib/dialects/oracledb/index.js has this code:

  // Node.js only have 4 background threads by default, oracledb needs one by connection
  if (this.driver) {
    process.env.UV_THREADPOOL_SIZE = process.env.UV_THREADPOOL_SIZE || 1;
    process.env.UV_THREADPOOL_SIZE =
      parseInt(process.env.UV_THREADPOOL_SIZE) + this.driver.poolMax;
  }

If the libuv threadpool has been initialized before this code is executed, this does not have the desired effect as UV_THREADPOOL_SIZE is only read once, when libuv initializes the threadpool. I don't think it is correct for the knex oracle dialect to do this. First of all because changing UV_THREADPOOL_SIZE at an arbitrary time during runtime is unreliable, but also because it is something for the actual oracle driver to work out.

I think the knex oracle driver should limit itself to logging a debug message if (UV_THREADPOOL_SIZE || 4) < this.driver.poolMax.

Background: This is not a theoretical problem. It was discovered precisely because the code above was executed too late to have an effect in the project that I am working on.

[briandamaged]

I agree that this is something that should be investigated further. I'm also concerned about how this code will behave in multi-client / multi-pool scenarios. (Speaking of which... the (UV_THREADPOOL_SIZE || 4) < this.driver.poolMax check probably would not be sufficient in this scenario. The check would work for each client individually, but not collectively)