Currently, all MongoClients use the same DNS Resolver (dns.promises.resolveSRV). that uses a thread pool across operations, so cancelling one operation could affect other clients

For client.close work, we'd want to cancel an in-progress DNS resolution upon close. A proposed solution for this is to in order to abort an in-progress is to create a custom DNS Resolver for the Node Driver that safely takes in an AbortController

Risks/Unknowns

• What is the impact of switching out of the dns.promises.resolve / using its thread pool?
  • Specifically what is unique to each resolver - what are the impacts of each client having its own resource-wise? (multiple threadpools?)
• What are the specifics of our custom DNS resolver design? Should it also run in the background?

Acceptance Criteria

Implementation Requirements

• Implement a custom DNS Resolver and no longer use dns.promises.resolve
• Pass in an abort controller that fires on close to the custom dns resolutions

Testing Requirements

• Assert that an in-progress SRV resolution aborts when client.close() is awaited