Hi John, Ok, that’s what I thought.
It’s the 502s that I’m trying to avoid in this instance. As far as I can tell, the retry mechanisms on a parent do not support any kind of “back off” mechanism, so you can have 100+ retries, but with an offline parent those “connection attempts” are exhausted in milliseconds. I would like to be able to allow a parent to be temporarily “unavailable” for anything up to ~2 seconds, and make the downstream client wait for the parent resource to be available again. It’s a rare edge case, but it’s a real one. The context here Is ABR video streaming, where a client has enough buffer to very occasionally wait a couple of extra seconds for its content, but an HTTP 502 would cause it to abort its stream. Thanks for your assistance, Nick From: John Rushford <jjrushf...@gmail.com> Date: Monday, February 20, 2023 at 6:03 PM To: dev@trafficserver.apache.org <dev@trafficserver.apache.org> Cc: Nick Dunkin <nick.dun...@vecima.com.invalid> Subject: Re: Configuring sleep times between parent connection retires? No a parent is not retried within the same transaction. If the configured number of retry counts is not exceeded, another parent would be chosen if there are other available parents. If there are no other available parents and the configs allow it, the transaction may go direct to the origin, go_direct in parent.config. If there are no other available parents and go_direct == false, the transaction fails and the client sees a 502 Sent from my iPhone > On Feb 20, 2023, at 3:18 PM, Nick Dunkin <nick.dun...@vecima.com.invalid> > wrote: > > Hi John, > > Thank you for the reply. > > Are you suggesting that I could have a parent marked down, with a very short > retry_time (~1 second), and it would be retried within the same transaction? > > I would have thought that at the point it’s marked down, the transaction > would end? > > Thanks > > Nick > > From: John J. Rushford <jjrushf...@gmail.com> > Date: Monday, February 20, 2023 at 3:21 PM > To: dev@trafficserver.apache.org <dev@trafficserver.apache.org>, Nick Dunkin > <nick.dun...@vecima.com.INVALID> > Subject: Re: Configuring sleep times between parent connection retires? > Nick, > > See the Parent Proxy Configurations, > https://docs.trafficserver.apache.org/admin-guide/files/records.config.en.html#parent-proxy-configuration > > You may need to do some tweaking. There is a sliding window, > proxy.config.http.parent_proxy.retry_time. When the failure threshold > ,proxy.config.http.parent_proxy.fail_threshold¶, on a parent is reached > the parent is marked down and will not be used until the retry window > has elapsed. when the window has elapsed, a failed parent will be > retried but, if the retry fails, no further attempts will be made to > that parent until the retry window has elapsed again. If the retry > succeeds, the parent is marked up. > > thanks > > John > >> On 2/20/23 12:02, Nick Dunkin wrote: >> >> Hi, >> >> If a parent cache is offline for a brief period of time (say < 3 >> seconds) I would like to know if there is way to configure a “sleep” >> between connection retries on a particular parent? >> >> The ability to configure the “connection attempts” is not useful here, >> as when the parent is completely offline the algorithm can run through >> many hundreds of connection attempts in milliseconds (confirmed from >> logs). >> >> The use case here is that, for us, it is preferable to make the client >> occasionally wait 1-3 seconds, than to return them a HTTP 502. >> >> I’ve started looking at the code, but I’d like to confirm that this is >> not already supported somehow. >> >> Many thanks >> >> Nick >> >> *Nick Dunkin* >> >> Director, Software Architecture >> >> Manager – Architecture and New Product Introduction >> >> *o: **+1 678.258.4071* >> >> *e:*nick.dun...@vecima.com <mailto:nick.dun...@vecima.com> >> >> cidimage001.png@01D6CC8C.6FC5A580 >>
