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From Stefan Eissing <stefan.eiss...@greenbytes.de>
Subject Re: TIL
Date Wed, 27 Apr 2016 14:17:48 GMT
Change was done in http://svn.apache.org/viewvc?view=revision&revision=327872 by brianp
in 2005 with message: 

"New version of ap_core_output_filter that does nonblocking writes
(backport from async-dev branch to 2.3 trunk)"

Since Brian put his name in CHANGES, it was probably him...

-Stefan


> Am 27.04.2016 um 14:52 schrieb Graham Leggett <minfrin@sharp.fm>:
> 
> On 27 Apr 2016, at 2:49 PM, Stefan Eissing <stefan.eissing@greenbytes.de> wrote:
> 
>> I had a look into 2.4.x this morning and while there are changes in filter brigade
setaside code, the basic "cleanup" of empty and meta buckets before the setaside is there
already.
>> 
>> I think this has not bween noticed before as 
>> 1. EOR is always followed by a FLUSH
>> 2. most bucket types survive the destruction of r->pool quite well, even pool
buckets silently morph
>> 3. even if transient buckets would reference pool memory, settings those aside after
destruction of r->pool, but before filter return would access freed, but not re-used memory
from the connection allocator - I think.
>> 
>> So far, I have seen no reasons why meta buckets should not just be setaside in core
filter. 0 length data buckets should also stay, IMHO, just ignored in the actual write.
>> 
>> I can only guess the original intent: 0-length data buckets sometimes happen during
some brigade read modes and if there are several FLUSH buckets in the brigade, it makes sense
to get rid of them also. But I think the space savings are minimal.
>> 
>> But there could be reasons for the current behavior, I overlooked. So, I am asking
around.
> 
> I don’t see any obvious reason for the current behaviour either - is it possible to
go back in history and confirm the log entry when it was introduced?
> 
> Regards,
> Graham
> —
> 


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