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Subject: question regarding removing a cachekey according the correct eviction
 policy from the outside
Date: Wed, 19 Jul 2006 11:50:34 +0200
Message-ID: <A955EA1F8FE31749AEC8C998082F6C7CD6E736@hai01.hippo.local>
Thread-Topic: question regarding removing a cachekey according the correct
 eviction policy from the outside
Thread-Index: AcarGMePSs3noxeCRdm3762g6J3Z0w==
From: "Ard Schrijvers" <a.schrijvers@hippo.nl>
To: <jcs-users@jakarta.apache.org>

Hello,

I have a question regarding removing keys:=20

In cocoon we have a JCSDefaultStore implementing =
org.apache.excalibur.store.Store interface. This interface has a method =
free(). store.free() (store can be the EHDefaultStore (ehcache) or the =
JCSDefaultStore, etc etc) is invoked by =
org.apache.excalibur.store.impl.StoreJanitorImpl when the JVM is low on =
memory.=20

Free() tries to remove cachekeys+response to free some memory. For =
example, the JCSDefaultStore does it like below:

public void free() {
        // TODO Find a better way
        MemoryCache memoryCache =3D =
this.cacheManager.getCache(region).getMemoryCache();
        Object[] keys =3D memoryCache.getKeyArray();
        if ( keys !=3D null && keys.length > 0 ) {
            final Object key =3D keys[0];
            try {
                memoryCache.remove((Serializable)key);
            } catch (Exception ignore) {               =20
            }
        }
}

The TODO speaks for itself. The EHDefaultStore using ehcache has this =
very same problem. Just removing cachekeys starting at index 0 does not =
improve the JVM when requests keep coming in, and the mainly important =
keys have been removed.=20

I was told that from the outside, it is impossible to remove keys from =
the ehcache according the correct eviction policy. Does this also hold =
for JCS? And, furthermore, perhaps I just want to overflow the cached =
responses to disk (without having reached maxobjects) instead of =
removing them. That would clear memory and let me keep the cached =
responses.=20

Is there something possible like,=20

public void remove(int numberKeys) and
public void overflow(int numberKeys)=20

and that this is done according the correct eviction policy?=20

Regards Ard

--=20

Hippo
Oosteinde 11
1017WT Amsterdam
The Netherlands
Tel  +31 (0)20 5224466
-------------------------------------------------------------
a.schrijvers@hippo.nl / http://www.hippo.nl
--------------------------------------------------------------=20

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