phpwiki-talk

[Phpwiki-talk] PHP persistent caching

[Dan F. <dfr...@cs...>]

Folks,

I have a question for experienced PHP developers. There is a lot of 
information I can imagine wanting to cache across sessions in PHP. For 
example in WikiLens, a ratings database, or per-item statistics (# 
ratings, averages, etc). This is stuff that will fit in-memory for the 
forseeable future.

What's the best way to do that in PHP? I've looked at a couple of PEAR 
modules (e.g., "Cache" included in PhpWiki), and they seem to be 
file-based. This is astonishing to me. Clearly memory can be 1000 times 
faster than disk (although there are usually memory-based disk caches, 
too). Is it really best to use file-based caches? I thought about 
writing a shared memory-based cache, and a colleague warned me away from 
it, saying shared memory access in PHP is iffy.

Thoughts?

Dan

RE: [Phpwiki-talk] PHP persistent caching

[Charles C. <ch...@ru...>]

Dan,

My understanding is that, to avoid potential memory (and other resource) leaks taking down the webserver, there has been a conscious
design decision to implement php as not keeping any memory context between http requests. I understand that there are ways around
this but they are not straightforward.

Regards,
Charles

> -----Original Message-----
> From: Dan Frankowski [mailto:dfr...@cs...]
> Sent: 03 May 2005 22:08
> To: 'php...@li...'
> Subject: [Phpwiki-talk] PHP persistent caching
> 
> Folks,
> 
> I have a question for experienced PHP developers. There is a lot of
> information I can imagine wanting to cache across sessions in PHP. For
> example in WikiLens, a ratings database, or per-item statistics (#
> ratings, averages, etc). This is stuff that will fit in-memory for the
> forseeable future.
> 
> What's the best way to do that in PHP? I've looked at a couple of PEAR
> modules (e.g., "Cache" included in PhpWiki), and they seem to be
> file-based. This is astonishing to me. Clearly memory can be 1000 times
> faster than disk (although there are usually memory-based disk caches,
> too). Is it really best to use file-based caches? I thought about
> writing a shared memory-based cache, and a colleague warned me away from
> it, saying shared memory access in PHP is iffy.
> 
> Thoughts?
> 
> Dan

Re: [Phpwiki-talk] PHP persistent caching

[Dan F. <dfr...@cs...>]

Charles,

Thanks for your thoughts.

My first thought would be to use a shared memory segment. See 
http://us4.php.net/shmop. Memory leaks are an issue, but not a 
show-stopper. One has to program well and be careful to get a 
high-performing system.

Dan

Charles Corrigan wrote:

>Dan,
>
>My understanding is that, to avoid potential memory (and other resource) leaks taking down the webserver, there has been a conscious
>design decision to implement php as not keeping any memory context between http requests. I understand that there are ways around
>this but they are not straightforward.
>
>Regards,
>Charles
>
>  
>
>>-----Original Message-----
>>From: Dan Frankowski [mailto:dfr...@cs...]
>>Sent: 03 May 2005 22:08
>>To: 'php...@li...'
>>Subject: [Phpwiki-talk] PHP persistent caching
>>
>>Folks,
>>
>>I have a question for experienced PHP developers. There is a lot of
>>information I can imagine wanting to cache across sessions in PHP. For
>>example in WikiLens, a ratings database, or per-item statistics (#
>>ratings, averages, etc). This is stuff that will fit in-memory for the
>>forseeable future.
>>
>>What's the best way to do that in PHP? I've looked at a couple of PEAR
>>modules (e.g., "Cache" included in PhpWiki), and they seem to be
>>file-based. This is astonishing to me. Clearly memory can be 1000 times
>>faster than disk (although there are usually memory-based disk caches,
>>too). Is it really best to use file-based caches? I thought about
>>writing a shared memory-based cache, and a colleague warned me away from
>>it, saying shared memory access in PHP is iffy.
>>
>>Thoughts?
>>
>>Dan
>>    
>>
>
>
>
>
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>_______________________________________________
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>  
>

Re: [Phpwiki-talk] PHP persistent caching

[Joby W. <joby@u.washington.edu>]

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Hash: SHA1

You can also use a file based cache on tmpfs.  The link below is a great
article on the basics of using tmpfs.

http://www-106.ibm.com/developerworks/library/l-fs3.html

You could even put an SQLite database on tmpfs, to get better performance.

Joby Walker
ITI SSG, University of Washington
- --
PGP key: https://staff.washington.edu/joby/joby-u-pub.asc


Dan Frankowski wrote:
> Folks,
> 
> I have a question for experienced PHP developers. There is a lot of
> information I can imagine wanting to cache across sessions in PHP. For
> example in WikiLens, a ratings database, or per-item statistics (#
> ratings, averages, etc). This is stuff that will fit in-memory for the
> forseeable future.
> 
> What's the best way to do that in PHP? I've looked at a couple of PEAR
> modules (e.g., "Cache" included in PhpWiki), and they seem to be
> file-based. This is astonishing to me. Clearly memory can be 1000 times
> faster than disk (although there are usually memory-based disk caches,
> too). Is it really best to use file-based caches? I thought about
> writing a shared memory-based cache, and a colleague warned me away from
> it, saying shared memory access in PHP is iffy.
> 
> Thoughts?
> 
> Dan
> 
> 
> 
> -------------------------------------------------------
> This SF.Net email is sponsored by: NEC IT Guy Games.
> Get your fingers limbered up and give it your best shot. 4 great events, 4
> opportunities to win big! Highest score wins.NEC IT Guy Games. Play to
> win an NEC 61 plasma display. Visit http://www.necitguy.com/?r=20
> _______________________________________________
> Phpwiki-talk mailing list
> Php...@li...
> https://lists.sourceforge.net/lists/listinfo/phpwiki-talk
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Re: [Phpwiki-talk] PHP persistent caching

[Reini U. <ru...@x-...>]

Dan Frankowski schrieb:
> I have a question for experienced PHP developers. There is a lot of 
> information I can imagine wanting to cache across sessions in PHP. For 
> example in WikiLens, a ratings database, or per-item statistics (# 
> ratings, averages, etc). This is stuff that will fit in-memory for the 
> forseeable future.
> 
> What's the best way to do that in PHP? I've looked at a couple of PEAR 
> modules (e.g., "Cache" included in PhpWiki), and they seem to be 
> file-based. This is astonishing to me. Clearly memory can be 1000 times 
> faster than disk (although there are usually memory-based disk caches, 
> too). Is it really best to use file-based caches? I thought about 
> writing a shared memory-based cache, and a colleague warned me away from 
> it, saying shared memory access in PHP is iffy.
> 
> Thoughts?

Are you aware about our max-size limitation of sessions
how we are using them?
If this could be solved we could put much more into regular sessions
and wouldn't need external libs, such as
   http://www.phpclasses.org/browse/package/439.html

I'm running a stable windows server with Turck MMCache for some time now 
using shmem for the internal bytecode.
   http://www.apachefriends.org/en/xampp.html
-- 
Reini Urban
http://xarch.tu-graz.ac.at/home/rurban/
http://phpwiki.org/

Re: [Phpwiki-talk] PHP persistent caching

[Dan F. <dfr...@cs...>]

Reini Urban wrote:

> Dan Frankowski schrieb:
>
>> I have a question for experienced PHP developers. There is a lot of 
>> information I can imagine wanting to cache across sessions in PHP. 
>> For example in WikiLens, a ratings database, or per-item statistics 
>> (# ratings, averages, etc). This is stuff that will fit in-memory for 
>> the forseeable future.
>>
>> What's the best way to do that in PHP? I've looked at a couple of 
>> PEAR modules (e.g., "Cache" included in PhpWiki), and they seem to be 
>> file-based. This is astonishing to me. Clearly memory can be 1000 
>> times faster than disk (although there are usually memory-based disk 
>> caches, too). Is it really best to use file-based caches? I thought 
>> about writing a shared memory-based cache, and a colleague warned me 
>> away from it, saying shared memory access in PHP is iffy.
>>
>> Thoughts?
>
>
> Are you aware about our max-size limitation of sessions
> how we are using them?


No, I don't know about this.

> If this could be solved we could put much more into regular sessions
> and wouldn't need external libs, such as
>   http://www.phpclasses.org/browse/package/439.html


Thanks for the ref! This looks like a useful package.

Note that I don't think stuffing the ratings DB (or stats like # rats or 
avg item rating) into each user session will help me. I want it cached 
*across* user sessions, so each user isn't burdened with re-reading, 
re-calculating.

I plan to try the shmem thing.

> I'm running a stable windows server with Turck MMCache for some time 
> now using shmem for the internal bytecode.
>   http://www.apachefriends.org/en/xampp.html


Cool, thanks.

Dan