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Re: h2 proxy and connection flow control

From: Amos Jeffries <squid3@treenet.co.nz>
Date: Fri, 22 Aug 2014 03:48:18 +1200
Message-ID: <53F614C2.3020509@treenet.co.nz>
To: ietf-http-wg@w3.org
On 22/08/2014 2:56 a.m., Tatsuhiro Tsujikawa wrote:
> On Thu, Aug 21, 2014 at 11:12 PM, Patrick McManus wrote:
> 
>>
>>
>>
>> On Thu, Aug 21, 2014 at 10:09 AM, Tatsuhiro Tsujikawa wrote:
>>
>>>
>>>
>>>
>>> ​In this scenario, proxy has no room to expand. Therefore I wrote that​
>>> all streams on backend connections are stalled.
>>>
>>>
>> This is my point. If the proxy really has no room to expand (its out of
>> ram) - then we've got a resource problem not a protocol problem. If it does
>> have more ram, then just use the protocol to open the window to match the
>> resources available.
>>
>>
> ​So if there is no ram to spend for that connection, is stalling entire
> connection inevitable consequence (and we should not care about it)? ​
> Connection flow control is limit the memory commitment for proxy then why
> do we need to extend it in the response to a client behavior?

For the browser connection the browser has explicitly indicated with its
matching stream and connection windows that it is happy for the other
streams to stall.
The proxy should not allow itself to stall the server connection. Namely
by reducing its window on all streams from that client as soon as it
detects the clients connection window getting low.

Proxies have to operate under the assumption that a number of other
clients and/or streams will be arriving very soon and need to use
resources. So no resource can be allocated beyond what can be passed on
quickly.

Amos
Received on Thursday, 21 August 2014 15:49:01 UTC

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