dns cache

[azu]

Though the call to dns.lookup() will be asynchronous from JavaScript's perspective, it is implemented as a synchronous call to getaddrinfo(3) that runs on libuv's threadpool. This can have surprising negative performance implications for some applications, see the UV_THREADPOOL_SIZE documentation for more information.
-- DNS | Node.js v12.9.0 Documentation

Maybe, dns lookup have negative performance implications.
I think that lookup should be cached.

However, dns lookup has not ttl option.

• Native DNS caching for lookups · Issue #5893 · nodejs/node

Related

• yahoo/dnscache: dnscache for Node
• LCMApps/dns-lookup-cache: An implementation to speed up the nodejs "dns.lookup" method by avoiding thread pool and using DNS TTL cache for particular hostname

[tinovyatkin]

Do you expect a lot of the equal queries? I think in this case the better solutions will be a LRU cache around, but not sure if it should be part of this library of wrap around. What do you think? Cache all requests with LRU cache?

[azu]

I think in this case the better solutions will be a LRU cache around, but not sure if it should be part of this library of wrap around.

Agree.

I'm ok that caching is out of scope of this library.

📝 I've filed this issue by following reason.
isLocalhost look like primitive function.
So, It is difficult that the library user care about the performance.

[tinovyatkin]

That's exactly the reason why I don't want to make it another lodash or request and keep the core thing simple. Depending on a use case you may or may not want to cache the result.

[tinovyatkin]

Digging deeper, we definitely can't replace lookup with resolve here, because it will loose hosts lookup and that is the most common use case for this library.