RE: mod_http2 / H2WindowSize default

[Bert Huijben]

> -Original Message-
> From: Yann Ylavic [mailto:ylavic@gmail.com]
> Sent: dinsdag 17 november 2015 00:49
> To: httpd-dev <dev@httpd.apache.org>
> Subject: Re: mod_http2 / H2WindowSize default
> 
> On Mon, Nov 16, 2015 at 8:23 PM, Bert Huijben <b...@qqmail.nl> wrote:
> >
> > Currently it looks like bodies of requests are not delivered over http/2
> unless I add a Content-Length header to the request.
> 
> Do you mean it does not work with the "Transfer-Encoding: chunked"
> header either?

Not following up on this:
http/2 strictly disallows transfer-encoding chunked.


http/2 always uses streams and framing... completely different system, but 
solves the same problem as chunking did in http/1.1.

If a content-length header exists, it is transferred... but it isn't used at 
the protocol level. 
(In most cases it is still used at the application level, but that is a 
different story)

Bert

Re: mod_http2 / H2WindowSize default

[Stefan Eissing]

Hmm, I have test cases with uploads without content-length, but those included 
a content-type...

Ok, adding a POST lacking both triggers the misbehaviour. Working on a fix...

//Stefan

> Am 16.11.2015 um 20:23 schrieb Bert Huijben <b...@qqmail.nl>:
> 
>> -Original Message-
>> From: Stefan Eissing [mailto:stefan.eiss...@greenbytes.de]
>> Sent: maandag 16 november 2015 12:41
>> To: dev@httpd.apache.org
>> Subject: Re: mod_http2 / H2WindowSize default
>> 
>> 
>>> Am 14.11.2015 um 11:14 schrieb Bert Huijben <b...@qqmail.nl>:
>>> 
>>>Hi,
>>> 
>>> I was wondering why mod_http2 currently uses a default window size of
>> 65536.
>> 
>> Pure mistake on my part. I put this in almost at the start of development and
>> never reviewed this.
>> 
>> Thanks for catching it. I am just about to commit a change that
>> a) set the default to 65535
>> b) will not send a setting for it to the client unless it has been 
>> configured to
>> have another value
>> 
>> I also removed the sending of the MAX_HEADER_LIST_SIZE, since it is not
>> enforced in any way currently.
>> 
>> Hope this change works for you.
> 
>   Thanks,
> 
> Those settings are enforced in (my) Serf implementation now, so my code will 
> see a difference. Thanks for fixing.
> (BTW: It is very easy to spot these two if you run nghttp2 in verbose mode 
> against httpd).
> 
> 
> As my http2 implementation in serf is coming closer to full-featured I'm 
> trying to exercise more and more things in httpd 2.4.17.
> 
> Currently it looks like bodies of requests are not delivered over http/2 
> unless I add a Content-Length header to the request.
> 
> 
> Serf is a client that is eager to use chunked encoding over http/1, so by 
> default it won't send such a header. And in http/2 this header is fully 
> optional as the existence of a body on a request is already available with a 
> flag on the headers frame.
> 
> I would love to see this fixed soon, as this is currently a blocker for me to 
> start testing Subversion over http/2.
> 
>   Bert

Re: mod_http2 / H2WindowSize default

[Stefan Eissing]

Fixed in r1714751.

> Am 17.11.2015 um 11:16 schrieb Stefan Eissing <stefan.eiss...@greenbytes.de>:
> 
> Hmm, I have test cases with uploads without content-length, but those 
> included a content-type...
> 
> Ok, adding a POST lacking both triggers the misbehaviour. Working on a fix...
> 
> //Stefan
> 
>> Am 16.11.2015 um 20:23 schrieb Bert Huijben <b...@qqmail.nl>:
>> 
>>> -Original Message-
>>> From: Stefan Eissing [mailto:stefan.eiss...@greenbytes.de]
>>> Sent: maandag 16 november 2015 12:41
>>> To: dev@httpd.apache.org
>>> Subject: Re: mod_http2 / H2WindowSize default
>>> 
>>> 
>>>> Am 14.11.2015 um 11:14 schrieb Bert Huijben <b...@qqmail.nl>:
>>>> 
>>>>   Hi,
>>>> 
>>>> I was wondering why mod_http2 currently uses a default window size of
>>> 65536.
>>> 
>>> Pure mistake on my part. I put this in almost at the start of development 
>>> and
>>> never reviewed this.
>>> 
>>> Thanks for catching it. I am just about to commit a change that
>>> a) set the default to 65535
>>> b) will not send a setting for it to the client unless it has been 
>>> configured to
>>> have another value
>>> 
>>> I also removed the sending of the MAX_HEADER_LIST_SIZE, since it is not
>>> enforced in any way currently.
>>> 
>>> Hope this change works for you.
>> 
>>  Thanks,
>> 
>> Those settings are enforced in (my) Serf implementation now, so my code will 
>> see a difference. Thanks for fixing.
>> (BTW: It is very easy to spot these two if you run nghttp2 in verbose mode 
>> against httpd).
>> 
>> 
>> As my http2 implementation in serf is coming closer to full-featured I'm 
>> trying to exercise more and more things in httpd 2.4.17.
>> 
>> Currently it looks like bodies of requests are not delivered over http/2 
>> unless I add a Content-Length header to the request.
>> 
>> 
>> Serf is a client that is eager to use chunked encoding over http/1, so by 
>> default it won't send such a header. And in http/2 this header is fully 
>> optional as the existence of a body on a request is already available with a 
>> flag on the headers frame.
>> 
>> I would love to see this fixed soon, as this is currently a blocker for me 
>> to start testing Subversion over http/2.
>> 
>>  Bert
> 

RE: mod_http2 / H2WindowSize default

[Bert Huijben]

> -Original Message-
> From: Stefan Eissing [mailto:stefan.eiss...@greenbytes.de]
> Sent: maandag 16 november 2015 12:41
> To: dev@httpd.apache.org
> Subject: Re: mod_http2 / H2WindowSize default
> 
> 
> > Am 14.11.2015 um 11:14 schrieb Bert Huijben <b...@qqmail.nl>:
> >
> > Hi,
> >
> > I was wondering why mod_http2 currently uses a default window size of
> 65536.
> 
> Pure mistake on my part. I put this in almost at the start of development and
> never reviewed this.
> 
> Thanks for catching it. I am just about to commit a change that
> a) set the default to 65535
> b) will not send a setting for it to the client unless it has been configured 
> to
> have another value
> 
> I also removed the sending of the MAX_HEADER_LIST_SIZE, since it is not
> enforced in any way currently.
> 
> Hope this change works for you.

Thanks,

Those settings are enforced in (my) Serf implementation now, so my code will 
see a difference. Thanks for fixing.
(BTW: It is very easy to spot these two if you run nghttp2 in verbose mode 
against httpd).


As my http2 implementation in serf is coming closer to full-featured I'm trying 
to exercise more and more things in httpd 2.4.17.

Currently it looks like bodies of requests are not delivered over http/2 unless 
I add a Content-Length header to the request.


Serf is a client that is eager to use chunked encoding over http/1, so by 
default it won't send such a header. And in http/2 this header is fully 
optional as the existence of a body on a request is already available with a 
flag on the headers frame.

I would love to see this fixed soon, as this is currently a blocker for me to 
start testing Subversion over http/2.

Bert

Re: mod_http2 / H2WindowSize default

[Yann Ylavic]

On Mon, Nov 16, 2015 at 8:23 PM, Bert Huijben  wrote:
>
> Currently it looks like bodies of requests are not delivered over http/2 
> unless I add a Content-Length header to the request.

Do you mean it does not work with the "Transfer-Encoding: chunked"
header either?

Regards,
Yann.

Re: mod_http2 / H2WindowSize default

[Stefan Eissing]

> Am 14.11.2015 um 11:14 schrieb Bert Huijben :
> 
> Hi,
>  
> I was wondering why mod_http2 currently uses a default window size of 65536.

Pure mistake on my part. I put this in almost at the start of development and 
never reviewed this.

Thanks for catching it. I am just about to commit a change that
a) set the default to 65535
b) will not send a setting for it to the client unless it has been configured 
to have another value

I also removed the sending of the MAX_HEADER_LIST_SIZE, since it is not 
enforced in any way currently.

Hope this change works for you. 

Cheers,

  Stefan
>  
> The http2 protocol defines a default window size of 65535, just 1 byte less 
> than the current default. Changing the default requires transferring this 
> setting to every client in the initial settings frame, while sticking to 
> 65535 would allow not doing that.
>  
> I can imagine that a completely different default makes sense (and allowing 
> to configure this certainly does), but this 1 byte of the protocol default 
> doesn’t make much sense to me.
>  
> This is just 6 bytes wasted in the handshake for no obvious benefit.
>  
>  
> I would recommend changing the default to 65535 or perhaps to something 
> completely different. (1MB… Don’t know). But sending a setting that is less 
> than 0.002% off the protocol default doesn’t make much sense to me.
>  
>  
> Note that this size is not really used by httpd itself. This size is used by 
> clients that need to transfer request bodies to httpd. This number of bytes 
> specifies the maximum number of bytes the client is allowed to send before it 
> needs to receive a WINDOW_UPDATE from the server, allowing it to transfer 
> more data.
>  
> The client determines the default in the other direction.
>  
>  
> Bert