Ikai,
I am guessing i am wrong somewhere in designing this cache solution.
Would appreciate if you can tell me where am i going wrong on this.
Let me try to explain it once again.
I have a set of properties which i load on first call to the service.
and the code I call in the service is as follows.
PropertiesCache _cache = PropertiesCache.getInstance();
My PropertiesCache is as follows.
-------------------------------------------------------------------
public class PropertiesCache {
private static final Logger log =
Logger.getLogger(PropertiesCache.class.getName());
private static PropertiesCache _instance;
private Cache cache;
private PropertiesCache() {
try {
log.info("In the PropertiesCache constructor");
cache =
CacheManager.getInstance().getCacheFactory().createCache(Collections.emptyMap());
//Loading the cache from the database.
//cache.put(Object, Object);
} catch (CacheException e) {
log.severe("Error in creating the Loading Cache");
}
public static synchronized PropertiesCache getInstance() {
if (_instance == null) {
_instance = new PropertiesCache();
}else{
log.info("Using existing cache instance and NO NEW
Instance is
created");
}
return _instance;
}
Also, Let me re-iterate what you said, you are suggesting me not to
play around with instance variable instead use the cache variable and
is there any way i can fetch the cache variable once the jvm restarts.
Appreciate all the efforts.
Thanks,
Rahul
On May 25, 5:08 pm, "Ikai L (Google)" <ika...@google.com> wrote:
> The instance itself will be recreated. If you store a value into Memcache,
> it will likely be there the next time you retrieve it. Try this out.
>
> It's not necessary to do what you've done here. When you create a Cache
> instance, you're really just creating a client to the cache, and you can do
> this each time you need it. There's no need to create a global, long-lived
> instance. What you're seeing is perfectly normal - Java objects will not
> have a longer lifespan than the JVM. If the JVM dies, so will all the
> instantiated objects.
>
>
>
> On Tue, May 25, 2010 at 1:28 PM, Rahul <rahul.jun...@gmail.com> wrote:
> > Toby,
>
> > I also had the same opinion but as you can see the previous code i
> > have given populates the cache again. I guess i am doing something
> > wrong. Appreciate if you can look at that and let me know if i have to
> > do something which i missing.
>
> > Thanks,
> > Rahul
>
> > On May 25, 4:00 pm, Toby Reyelts <to...@google.com> wrote:
> > > Rahul,
>
> > > If you're using App Engine's MemcacheService directly (or indirectly, for
> > > example through our JSR 107 support), then you are talking to backend
> > > memcache instances that have lifetimes separate from your JVMs.
>
> > > I.E. MemcacheServiceFactory.getMemcacheService<
> >http://code.google.com/appengine/docs/java/javadoc/com/google/appengi...()
>
> > > does
> > > not create a new memcache backend - it just "connects" to an existing
> > one.
> > > You have one logical memcache backend that is shared between all of your
> > > application's JVMs.
>
> > > On Tue, May 25, 2010 at 3:12 PM, Rahul <rahul.jun...@gmail.com> wrote:
> > > > Ikai,
>
> > > > I am not sure what you mean by Memcache instances stays up because i
> > > > tried the following code and everytime when a new jvm instance is
> > > > created, the cache instance is also created again. Below is the code i
> > > > am using, let me know if i am missing anything or not doing anything
> > > > correct.
>
> > > > Request comes from the following code:
>
> > > > MyCache _cache = MyCache.getInstance();
> > > > redirectUrl = _cache.findInCache(requestedURI);
>
> > > > MyCache Class:
>
> > > > private static MyCache _instance;
> > > > private Cache cache;
>
> > > > public static synchronized MyCache getInstance() {
> > > > if (_instance == null) {
> > > > _instance = new MyCache();
> > > > }else{
> > > > log.info("Using existing cache instance and NO
> > NEW
> > > > Instance is
> > > > created");
> > > > }
>
> > > > return _instance;
> > > > }
>
> > > > and in the constructor i am creating new cache fetching everything
> > > > from the database.
>
> > > > Also, i have a listener in place which tells me when the new jvm
> > > > instance is started.
>
> > > > Thanks,
> > > > Rahul
>
> > > > On May 24, 3:56 pm, "Ikai L (Google)" <ika...@google.com> wrote:
> > > > > Memcache instances stay up. They're shared, namespaced (security)
> > > > instances
> > > > > and will more likely than not outlive the lifecycles of your
> > application
> > > > > instances.
>
> > > > > On Sun, May 23, 2010 at 11:17 PM, Tristan <
> > tristan.slomin...@gmail.com
> > > > >wrote:
>
> > > > > > Does anyone know the answer to this:
>
> > > > > > If all the JVMs are killed, does the memcache stick around or is it
> > > > > > recycled? (I know memcache expires eventually, just curious if it
> > is
> > > > > > possible for it to carry data across JVM valley of death)
>
> > > > > > Cheers,
>
> > > > > > Tristan
>
> > > > > > --
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> > > > > --
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> > > > > Developer Relations, Google App Engine
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>
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> --
> Ikai Lan
> Developer Programs Engineer, Google App Engine
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>
> ----------------
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