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 ;)
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Niklas Edmundsson, Admin @ {acc,hpc2n}.umu.se | [EMAIL PROTECTED]
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I'd love to, but I'm worried about my vertical hold.
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