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From Phil Pinkerton <pcpinker...@gmail.com>
Subject Re: [users@httpd] Cache issues
Date Mon, 28 Sep 2009 10:25:58 GMT


Jonathan Zuckerman wrote:
> On Fri, Sep 25, 2009 at 10:54 AM, Phil Pinkerton <pcpinkerton@gmail.com> wrote:
>   
>> On Fri, Sep 25, 2009 at 12:45 PM, Jonathan Zuckerman <j.zuckerman@gmail.com>
>> wrote:
>>     
>>> On Fri, Sep 25, 2009 at 6:15 AM, Phil Pinkerton <pcpinkerton@gmail.com>
>>> wrote:
>>>       
>>>> Anyone experience performance issues with regards to Apache cache ?
>>>>
>>>> Â From time to time we are experience access issues ( users accessing
>>>> Subversion ) that seem to be due to an over loaded Apache cache. We
>>>> suspect
>>>> the cache because when we refresh (stop,start) the Apache server the
>>>> problems goes away for a time. This happens so regularly we have set
>>>> crontab
>>>> to refresh every morning during our maintenance period. And this has
>>>> reduced
>>>> the number of problems.
>>>>
>>>> This is Apache 2.2.11 running on a Solaris Sparc server. Providing HTTPD
>>>> services for or Subversion users,
>>>>
>>>> Any thoughts on managing Apache Cache ?
>>>>
>>>> --
>>>> " The fundamental principle here is that the justification for a
>>>> physical
>>>> concept lies exclusively in its clear and unambiguous relation to the
>>>> facts
>>>> that it can be experienced" Â  AE
>>>>
>>>> Please Feed and Educate the Children... it's the least any of us can do.
>>>>
>>>>
>>>>         
>>> Is there anything at all in the error log to suggest it's the cache? I
>>> think that bouncing the web server affects a lot of other stuff
>>> besides the cache..
>>>
>>>       
>> Nothing in the logs tells us anything about why we get the "Other" error
>> messages, but if it's not a cache problem (possibly related to LDAP), why
>> would a recycle fix it?
>>     
>>> ---------------------------------------------------------------------
>>> The official User-To-User support forum of the Apache HTTP Server Project.
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>>>
>>>       
>>
>> --
>> " The fundamental principle here is that the justification for a physical
>> concept lies exclusively in its clear and unambiguous relation to the facts
>> that it can be experienced" Â  AE
>>
>> Please Feed and Educate the Children... it's the least any of us can do.
>>
>>
>>     
>
> When you restart the webserver every thread completes and stops
> handling requests, every process ends, _everything_ about the
> webserver stops and then starts again, this potentially affects more
> than just the files used by mod_cache.
> Have you looked at the diskspace used by mod_cache to see if there are
> any patterns to it (size, usage, whatever) when the webserver stops
> responding?  How about monitoring the health of the box to see if
> anything else could be the issue (CPU pegged, RAM, disk..)?  Anything
> at all in apache error logs.
> I'm sorry that I don't have more suggestions; mod_cache might indeed
> be the problem but from a troubleshooting standpoint it seems to me
> that you're narrowing down the possible causes just a bit too
> recklessly.
>
>   
Not sure you need to be so abusive. When this issue arises  100's of 
developers  cannot access Subversion, several automated scripts fail to 
checkout from Subversion and it could literally halt production. We 
quickly implemented this "band-aid" to keep production running and since 
the refresh takes only about 3 seconds and works to clear the issue. I 
would think letting production crash while taking detail RCA would be 
much worse than reckless. We don't have the Apache expertise and we did 
very well to at least find a short term solution. I asked this group for 
help not criticism.

The unnecessary "reckless" comment aside your questions are valid and 
maybe somewhat useful.

Thanks for the assistance.

Phil

> ---------------------------------------------------------------------
> The official User-To-User support forum of the Apache HTTP Server Project.
> See <URL:http://httpd.apache.org/userslist.html> for more info.
> To unsubscribe, e-mail: users-unsubscribe@httpd.apache.org
>    "   from the digest: users-digest-unsubscribe@httpd.apache.org
> For additional commands, e-mail: users-help@httpd.apache.org
>
>
>   


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