Let me first explain the ConnectTimeout
- Connection timeout is used when opening a communications link to the remote resource.
- A java.net.SocketTimeoutException is thrown if the timeout expires before the connection can be established.
@DebugHorror Point 3 DNS Resolution is the main culprit in this case.
- It’s quite common that some larger domains will be using a DNS round robin configuration – essentially having the same domain mapped to multiple IP addresses.
- This introduces a new challenge for a timeout against such a domain, simply because of the way HttpClient will try to connect to that domain that times out:
- HttpClient gets the list of IP routes to that domain:
- it tries the first one – that times out (with the timeouts we configure(15 sec))
- it tries the second one – that also times out (15 sec)
- and so on …
We can see the same in below screenshot:
