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From Paul Querna <p...@querna.org>
Subject Re: 3.0, the 2011 thread.
Date Sat, 18 Jun 2011 19:45:39 GMT
2011/6/18 Igor Galić <i.galic@brainsware.org>:
>
>
> ----- Original Message -----
>> On Friday 17 June 2011, Graham Leggett wrote:
>> > We used openssl to make our non blocking event driven stuff work,
>> > and it works really well (once you've properly handled
>> > SSL_ERROR_WANT_READ and SSL_ERROR_WANT_WRITE). There is no reason
>> > I can see that would stop us using openssl to be async in httpd,
>> > we just need to refactor the mod_ssl code to actually do it.
>>
>> Someone (Paul?) once told me that openssl is not very good when it
>> comes to async access to the session cache (which could need network
>> io if using memcached), CRLs (which I could imagine to reside in
>> LDAP)
>> and similar things. But this would have to be evaluated.
>>
>> > The tricky part with event driven code is the really bad support
>> > for   event driven file access. We used libev as our core event
>> > loop, which does a significant amount of work to make files and
>> > sockets work the same way in the event loop as best it can in a
>> > portable way. Don't know of any other event loop that does this.
>> > It's difficult trying to do the event driven thing if you
>> > intersperse event driven socket handling with blocking file
>> > handling, you end up with many requests blocked by an unrelated
>> > system call.
>>
>> Yes, I guess we would need a pool of lightweight worker threads that
>> does the file io (especially sendfile). Those threads would probably
>> get by with very small stack sizes and use little resources. If the
>> event library we choose already has this built in, we can of course
>> use that, too.
>
> This kind of reminds me of the architecture of Apache Traffic Server
> see http://www.slideshare.net/zwoop/rit-2011-ats
>

Yes, ATS is the right model I think, but I don't think the... C++isms
and general bagage that comes along with it are ideal for httpd
though?

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