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From Sudheer Vinukonda <sudheervinuko...@yahoo.com>
Subject Re: collapsed forwarding still leaking to origin
Date Thu, 18 Jun 2020 15:37:00 GMT
That’s odd. 

Since you’ve

>> proxy.config.http.cache.open_write_fail_action 4


it seems like that should be sufficient to ensure concurrent requests aren’t leaked. How
many requests are you seeing going up to the Origin per ATS server?

The status code of 303 and crc=ERR_CONNECT_FAIL does seem to imply the request never got proxied
and was short circuited from within ATS (by the CF plugin).

On a related note, ATS 9.x (and backported to 8.1.x) supports a new cleaner/efficient way
of doing the thundering herd protection all within ATS core without needing to use the CF
plugin (which is being deprecated in 9.x). You could consider moving to 8.1.x to leverage
that.

https://github.com/apache/trafficserver/pull/6294

It’s configured by setting 

>> proxy.config.http.cache.open_write_fail_action 5

https://docs.trafficserver.apache.org/en/latest/admin-guide/files/records.config.en.html

> On Jun 18, 2020, at 7:02 AM, Patrick O'Brien <patrickobrien@tetrisblocks.net> wrote:
> 
> 
> Can confirm that we are also seeing this, but only at times of extremely high traffic
(e.g. 20Gbps). 
> 
>> On Thu, Jun 18, 2020 at 5:57 AM ezko <erez.koler@harmonicinc.com> wrote:
>> Hi,
>> we are evaluating ATS 8.0.7 as reverse proxy for caching linear video
>> (multiple instantaneous hits for the same content).
>> we enabled RWW and collapsed forwarding as described in the docs.
>> it works really well , but sometimes we see leaks to the origin. 
>> when leaking happens , we are seeing 303 with Cache Result Code =
>> ERR_CONNECT_FAIL
>> 
>> Our first priority is to protect the origin (because it fails when flooded).
>> when using RWW + ColFw , what is the recommended config to best protect the
>> origin ? 
>> 
>> BR,
>> Erez
>> 
>> Our config:
>> proxy.config.http.cache.open_write_fail_action 4
>> proxy.config.cache.enable_read_while_writer 1
>> proxy.config.http.redirection_enabled 1
>> proxy.config.http.number_of_redirections 10
>> proxy.config.http.redirect_use_orig_cache_key 1
>> proxy.config.http.background_fill_active_timeout 0
>> proxy.config.http.background_fill_completed_threshold 0
>> proxy.config.cache.max_doc_size 0
>> proxy.config.cache.read_while_writer.max_retries 10
>> proxy.config.cache.read_while_writer_retry.delay 50
>> proxy.config.http.cache.max_open_read_retries 5
>> proxy.config.http.cache.open_read_retry_time 10
>> proxy.config.http.wait_for_cache 1
>> 
>> and we also tried changing this one:
>> proxy.config.http.cache.max_open_write_retries 50
>> 
>> remap:
>> @plugin=collapsed_forwarding.so @pparam=--delay=40 @pparam=--retries=5
>> 
>> 
>> 
>> --
>> Sent from: http://apache-traffic-server.24303.n7.nabble.com/

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