Ard Schrijvers wrote:
On 7/13/06, Andreas Hartmann <[EMAIL PROTECTED]> wrote:
...<parameter name="overflow-to-disk" value="false"/>
Is there a special reason why this is set to "false"?...
It's because in that case we only want a short-term cache. There are more
parameters which might help, they are read by the
src/java/org/apache/cocoon/components/store/impl/EHDefaultStore.java class
IIUC.
Beside the fact that I am (have to begin but is on my agenda) going to write
a best practice on these kind of things, I will try some to explain some
stuff here in short:
Ard, thanks for your comprehensive answers!
I'll take a closer look at your recommendations.
Will you announce your how-to on the list?
-- Andreas
First of all, make sure you have the EHDefaultStore.java from the trunk. This
one has some important patches.
Now, a common configuration for your store would be:
<store logger="core.store"> <parameter name="maxobjects" value="1000"/>
<parameter name="eternal" value="false"/> <parameter name="timeToLiveSeconds"
value="0"/> <!-- 1 day --> <parameter name="timeToIdleSeconds"
value="86400"/> <parameter name="overflow-to-disk" value="true"/> <parameter
name="diskpersistent" value="true"/> </store>
This means, a maximum of 1000 object (keys+response) are kept in memory.
Since eternal is false, timeToLiveSeconds and timeToIdleSeconds are taken
into account. Is timeToLiveSeconds < timeToIdleSeconds, then only
timeToIdleSeconds matters. In the configuration above, after 1 day of not
being used, the cachekey is removed from cache.
So, when overflow-to-disk is set to true, and you don't have eternal false
and timeToIdleSeconds > 0, then ones a cachekey is in memory/disk, it will
never be removed (apart from the StoreJanitor which when low on memory lets
the EHDefaultStore free its cache ---though this couldn't be implemented
worse because it just starts removing cachekeys/reponses from index 0 (which
are commonly the most important ones) instead of removing them according the
correct eviction policy. I have posted already to the ehcache mailinglist how
to find the LRU one, but not yet got an answer--- and I assume you dont use
eventAware cache actively removing keys )
So, it is very well possible, to let your cache grow INFINITELY large.
Setting timeToIdleSeconds is important. Certainly when for example you have
cachekeys including current date (though, watch out with these kind of cache
practices because your cache could grow very large)
diskpersistent is added to be configurable since short, but does not really
matter. It only indicates persistent cache between JVM restarts (used to be
default true).
If you are working with a cocoon versions < 2.1.9, and you dont want to
switch, but want to use the latest EHDefaultStore, just add the
EHDefaultStore.java from trunk in your
src/java/country/yourcomapany/cocoon..., and add to user.roles:
<role name="org.apache.excalibur.store.Store" shorthand="store"
default-class="country.yourcompany.cocoon.components.store.impl.EHDefaultStore"
/>
Now, just check it out configuring timeToIdleSeconds to 5 secs or something.
Then look at the StatusGenerator, and you will see cachekeys being dumped
after 5 sec (by the way, dont refresh the StatusGenerator to often then,
because looking at the StatusGenerator uses the keys, implying they are not
idle for another 5 sec... :-) )
Hope things are little clearer...
Regards Ard
-Bertrand
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Andreas Hartmann
Wyona Inc. - Open Source Content Management - Apache Lenya
http://www.wyona.com http://lenya.apache.org
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