retry and stats behavior when using request hedging

[Brian W]

Hi,

I'm enabling envoy request hedging via the "x-envoy-hedge-on-per-try-timeout" client header in client requests and am trying to understand what happens at various points if there is no response from upstream.

I have the following settings set via client headers:

max retries == 3

per try timeout == 400ms

request timeout == 1500ms

Assuming no upstream response, will envoy do this:

0ms: request sent

400ms: one retry sent as a hedged request

1500ms: return 504 timeout

or will it do something else because max retries are set to 3?  Do max retries have any effect when request hedging is enabled?   

Also does envoy emit the per try timeout stat at 400ms, and a request timeout stat at 1500ms, same as without request hedging?

Thanks,

Brian