Cache issues

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Anyone experience performance issues with regards to Apache cache ?

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" AE

Please Feed and Educate the Children... it's the least any of us can do.

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Anyone experience performance issues with regards to Apache cache ?

=
=A0From time to time we are experience access issues ( users accessing Subv=
ersion ) 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 refr=
esh every morning during our maintenance period. And this has reduced the n=
umber of problems.


This is Apache 2.2.11 running on a Solaris Sparc server. Providing HTTP=
D services for or Subversion users,

Any thoughts on managing Apache =
Cache ?

--
" The fundamental principle here i=
s that the justification for a physical concept lies exclusively in its cle=
ar and unambiguous relation to the facts that it can be experienced" =
=A0 AE


Please Feed and Educate the Children... it's the least any of us ca=
n do.



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Re: Cache issues

On Fri, Sep 25, 2009 at 6:15 AM, Phil Pinkerton wro=
te:
> Anyone experience performance issues with regards to Apache cache ?
>
>  From time to time we are experience access issues ( users accessing
> Subversion ) that seem to be due to an over loaded Apache cache. We suspe=
ct
> 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 cron=
tab
> to refresh every morning during our maintenance period. And this has redu=
ced
> 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 fac=
ts
> that it can be experienced"   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..

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Re: Cache issues

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On Fri, Sep 25, 2009 at 12:45 PM, Jonathan Zuckerman
wrote:

> On Fri, Sep 25, 2009 at 6:15 AM, Phil Pinkerton
> wrote:
> > Anyone experience performance issues with regards to Apache cache ?
> >
> > 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" 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.
> See 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
>
>


--
" 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" AE

Please Feed and Educate the Children... it's the least any of us can do.

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Re: Cache issues

On Fri, Sep 25, 2009 at 10:54 AM, Phil Pinkerton wr=
ote:
>
>
> On Fri, Sep 25, 2009 at 12:45 PM, Jonathan Zuckerman om>
> wrote:
>>
>> On Fri, Sep 25, 2009 at 6:15 AM, Phil Pinkerton
>> wrote:
>> > Anyone experience performance issues with regards to Apache cache ?
>> >
>> >  From time to time we are experience access issues ( users access=
ing
>> > 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 HTT=
PD
>> > 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"   AE
>> >
>> > Please Feed and Educate the Children... it's the least any of us can d=
o.
>> >
>> >
>>
>> 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 Projec=
t.
>> See for more info.
>> To unsubscribe, e-mail: users-unsubscribe@httpd.apache.org
>>   "   from the digest: users-digest-unsubscribe@httpd.apache.o=
rg
>> For additional commands, e-mail: users-help@httpd.apache.org
>>
>
>
>
> --
> " The fundamental principle here is that the justification for a physical
> concept lies exclusively in its clear and unambiguous relation to the fac=
ts
> that it can be experienced"   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.

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Re: Cache issues

Jonathan Zuckerman wrote:
> On Fri, Sep 25, 2009 at 10:54 AM, Phil Pinkerton > wrote:
> =20
>> On Fri, Sep 25, 2009 at 12:45 PM, Jonathan Zuckerman l.com>
>> wrote:
>> =20
>>> On Fri, Sep 25, 2009 at 6:15 AM, Phil Pinkerton m>
>>> wrote:
>>> =20
>>>> Anyone experience performance issues with regards to Apache cache ?
>>>>
>>>> Â From time to time we are experience access issues ( users acc=
essing
>>>> 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 H=
TTPD
>>>> 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 th=
e
>>>> facts
>>>> that it can be experienced" Â AE
>>>>
>>>> Please Feed and Educate the Children... it's the least any of us can=
do.
>>>>
>>>>
>>>> =20
>>> 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..
>>>
>>> =20
>> Nothing in the logs tells us anything about why we get the "Other" err=
or
>> messages, but if it's not a cache problem (possibly related to LDAP), =
why
>> would a recycle fix it?
>> =20
>>> ------------------------------------------------------------ ---------=

>>> The official User-To-User support forum of the Apache HTTP Server Pro=
ject.
>>> See for more info.
>>> To unsubscribe, e-mail: users-unsubscribe@httpd.apache.org
>>> Â " Â from the digest: users-digest-unsubscribe@httpd.apa=
che.org
>>> For additional commands, e-mail: users-help@httpd.apache.org
>>>
>>> =20
>>
>> --
>> " The fundamental principle here is that the justification for a physi=
cal
>> 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 d=
o.
>>
>>
>> =20
>
> 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.
>
> =20
Not sure you need to be so abusive. When this issue arises 100's of=20
developers cannot access Subversion, several automated scripts fail to=20
checkout from Subversion and it could literally halt production. We=20
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=20
would think letting production crash while taking detail RCA would be=20
much worse than reckless. We don't have the Apache expertise and we did=20
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=20
maybe somewhat useful.

Thanks for the assistance.

Phil

> ------------------------------------------------------------ ---------
> The official User-To-User support forum of the Apache HTTP Server Proje=
ct.
> See 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
>
>
> =20


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Re: Cache issues

On Mon, 2009-09-28 at 06:25 -0400, Phil Pinkerton wrote:
>
> Jonathan Zuckerman wrote:
> > On Fri, Sep 25, 2009 at 10:54 AM, Phil Pinkerton wrote:
> >
> >> On Fri, Sep 25, 2009 at 12:45 PM, Jonathan Zuckerman
> >> wrote:
> >>
> >>> On Fri, Sep 25, 2009 at 6:15 AM, Phil Pinkerton
> >>> 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.
> >>> See for more info.
> >>> To unsubscribe, e-mail: users-unsubscribe@httpd.apache.org
> >>> Â " Â from the digest: users-digest-unsubscribe@httpd.apache.org
> >>> For additional commands, e-mail: users-help@httpd.apache.org
> >>>
> >>>
> >>
> >> --
> >> " 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

How frequently does it occur if the cache is disabled?

Cheers

Tom


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