Sorry I can’t get it .
If host A has added the counter and failed to response, the request
would be failed over to host B with successful response, so the
counter would be added twines. Wouldn’t it ?
Then a condition must occur where host A fails right after processing
request, they usually fail before accepting a request, it also depends
the timeout for a request. And it also depends what nginx considers a
nginx might not fail a host when it does not return from accepting a
You will have to simulate this to find out the conditions for a fail.
Posted at Nginx Forum: