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21 messages in org.apache.httpd.devRe: Is async the answer| From | Sent On | Attachments |
|---|---|---|
| Akins, Brian | Jan 18, 2008 10:51 am | |
| Justin Erenkrantz | Jan 18, 2008 11:16 am | |
| Colm MacCarthaigh | Jan 18, 2008 11:20 am | |
| Akins, Brian | Jan 18, 2008 11:26 am | |
| Akins, Brian | Jan 18, 2008 11:30 am | |
| Colm MacCarthaigh | Jan 18, 2008 12:07 pm | |
| Akins, Brian | Jan 18, 2008 1:16 pm | |
| Colm MacCarthaigh | Jan 18, 2008 1:28 pm | |
| Ruediger Pluem | Jan 18, 2008 2:30 pm | |
| Justin Erenkrantz | Jan 18, 2008 4:33 pm | |
| Niklas Edmundsson | Jan 19, 2008 3:53 am | |
| Graham Leggett | Jan 19, 2008 4:45 am | |
| Davi Arnaut | Jan 19, 2008 6:57 am | |
| Jim Jagielski | Jan 19, 2008 7:04 am | |
| Graham Leggett | Jan 19, 2008 8:01 am | |
| Henrik Nordström | Jan 19, 2008 1:14 pm | |
| Henrik Nordström | Jan 19, 2008 1:19 pm | |
| Davi Arnaut | Jan 19, 2008 3:29 pm | |
| Graham Leggett | Jan 20, 2008 7:44 am | |
| Akins, Brian | Jan 22, 2008 10:03 am | |
| Akins, Brian | Jan 22, 2008 10:07 am |

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| Subject: | Re: Is async the answer | Actions... |
|---|---|---|
| From: | Niklas Edmundsson (nik...@acc.umu.se) | |
| Date: | Jan 19, 2008 3:53:31 am | |
| List: | org.apache.httpd.dev | |
On Fri, 18 Jan 2008, Ruediger Pluem wrote:
The proxy that the LiveJournal folks wrote, I think, copies all the data from the origin server into a file and then uses sendfile to send to the client...
Erm, so does the one we wrote, mod_disk_cache ;p
IMHO it doesn't for the first request of the entity (the request that causes the entity to be cached)
Which is why it doesn't scale with large files, and I hacked it to do that to be usable with DVD images on ftp.acc.umu.se (http://issues.apache.org/bugzilla/show_bug.cgi?id=39380 - you might remember the first try to merge some of it). Yes, it has its flaws, but it solves the problem for us. I think that some people has tried it in a proxy setting too with pretty OK result. But this was really off-topic ;)
Getting to the point, I share Brians concerns with going async just for the async sake, for similar reasons:
- People are having problems with making modules even thread safe (see mod_example), forcibly adding async to the mix will raise the bar even higher for people who needs to whip up a simple module. - Callback semantics are messy when they go wrong, debugging can be a pain. - Threads are rather cheap, even on linux since the advent of NPTL. - Performance benefits are unclear.
Given that, there are obvious optimisations that can be, and have been, made. The ones in trunk aimed at not hogging a worker thread for simply writing the remaining data to the client for example. From what I've understood this class of changes doesn't really affect modules.
Also, if there is a way of adding async having it optional in modules then I see no problem with adding it as long as there are cases where it actually helps, other than adding it to the supported buzzwords list ;)
/Nikke - who probably ended up off topic after all ;) -- -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Niklas Edmundsson, Admin @ {acc,hpc2n}.umu.se | nik...@acc.umu.se --------------------------------------------------------------------------- I'd love to, but I'm worried about my vertical hold. =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=







