mod_cache performance

[Brian Akins <br...@turner.com>]

Greetings all,

I may finally have some time to work on some mod_cache issues that have 
been nagging me.  Mostly performance things.  I really want to stop 
maintaining my own version here, but to do that mod_cache needs to be 
sped up a bit.

I'm setting up a dev environment now, so hopefully I should have 
something usable soon.  Unfortunately, most patches I have submitted for 
mod_cache have basically been ignored.

Are there any general ideas you guys have in where the performance 
bottlenecks may be?

A short list I have (mostly mod_disk_cache):

-read_table and read_array seem slower than they should be
-"thundering herd" when a popular object expires
-writing out request headers when not varying

I have submitted patches for some of these in the past, but I will try 
to quantify the performance implications of these.


-- 
Brian Akins
Lead Systems Engineer
CNN Internet Technologies

Re: mod_cache performance

[Parin Shah <pa...@gmail.com>]

We tried to solve thundering herd problem wih cache-requester module
which I have not committed yet. It is currently available on source
forge.

I have not found enough time to work on it after summer of code was
over as I was busy with my thesis, internship. now I have just
relocated to calif recently. So, I should be actively working (in
couple of weeks probably) on cache-requester soon once things settle
down for me.

meanwhile, feel free to use mod-cache-requester if you find it useful.
Let me know if I could be of any help.

-Parin.

On 1/12/06, Graham Leggett <mi...@sharp.fm> wrote:
> Brian Akins wrote:
>
> > A short list I have (mostly mod_disk_cache):
> >
> > -read_table and read_array seem slower than they should be
> > -"thundering herd" when a popular object expires
>
> Thundering herd was one of the original design goals of the new cache
> that was never fully followed through. With the work getting the cache
> to handle transfer failures gracefully, the next logical step is to
> solve thundering herd.
>
> > -writing out request headers when not varying
> >
> > I have submitted patches for some of these in the past, but I will try
> > to quantify the performance implications of these.
>
> Submit them to bugzilla to make sure they do not drop on the floor, then
> nag this list. I will be off the air till the end of the month to have a
> holiday, but after that I definitely plan to get my hands dirty.
>
> Regards,
> Graham
> --
>
>
>

Re: mod_cache performance

[Graham Leggett <mi...@sharp.fm>]

Brian Akins wrote:

> A short list I have (mostly mod_disk_cache):
> 
> -read_table and read_array seem slower than they should be
> -"thundering herd" when a popular object expires

Thundering herd was one of the original design goals of the new cache 
that was never fully followed through. With the work getting the cache 
to handle transfer failures gracefully, the next logical step is to 
solve thundering herd.

> -writing out request headers when not varying
> 
> I have submitted patches for some of these in the past, but I will try 
> to quantify the performance implications of these.

Submit them to bugzilla to make sure they do not drop on the floor, then 
nag this list. I will be off the air till the end of the month to have a 
holiday, but after that I definitely plan to get my hands dirty.

Regards,
Graham
--