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From "Bill Stoddard" <>
Subject RE: mod_cache CacheMaxStreamingBuffer
Date Thu, 12 Dec 2002 17:44:46 GMT
I expect mod_cache/mod_mem_cache is close to moving out of experimental.  I
have no confidence in mod_disk_cache (mainly because I have not spent much
time on it in months).  None of the changes I am proposing would
substantially impact the stability (famous last words :-).

  -----Original Message-----
  From: Estrade Matthieu []
  Sent: Thursday, December 12, 2002 11:54 AM
  Subject: Re: mod_cache CacheMaxStreamingBuffer

  what i remember is cache is able to cache unknown size document with
  i will try to draw it:

  first brigade, no length, if no EOS bucket, saving data in temp brigade
  second brigade, if no EOS, concat data to temp_brigade
  until finding an EOS bucket, or total length is more than

  All of this is starting line 630 of mod_cache.c

  then, write_headers, and write_body (with temp brigade if the document is
handled with more than 1 brigade), which are pointing on disk or mem cache
writing functions depending on setting.

  how long do you think the cache will stay in experimental
  I am using it a lot in my product which is used by many customers
  I found any big problems
  in worker, reverse_proxy with mem_cache, i have like 300 request on
backend for 120 000 request on reverse proxy
  It increase performance a lot



  Bill Stoddard wrote:

I confirm the CacheMaxStreamingBuffer is a source of misconfiguration
Using the MCacheMaxObjectSize could me a good thing.
In case of CacheMaxStreamingBuffer used, i don't know how
MCacheMaxObjectSize is used for because if a document is bigger than
MaxStreamingBuffer, it will be never cached.
are you sure MaxStreamingBuffer is not used in disk_cache ?
this directive is to store all the brigade before saving the entire data
with the write_headers and write_body functions, pointing on disk or mem
writing functions.
I think it's the same for disk and mem cache.

I need to look at the old code, but if i recall correctly, mod_mem_cache
reject attempting to cache an object whose length was unknown (see the call
cache_create_entity() in mod_cache). mod_disk_cache otoh would happily
to cache objects whose size was not know at the start. Remember that
mod_disk_cache is just writing cache objects to disk and does not need to
allocate memory to hold/prefetch the object.

In the same time, could you answer my old mail with the
CacheSlashEndingUrl patch i made is usefull or not ?

Yea, I was just looking at that. I think we can eliminate that check. I was
originally afraid that this would muck up negotiation but the cache does not
work with negotiated content now anyway.


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