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From "Carsten Ziegeler" <cziege...@s-und-n.de>
Subject RE: Store surviving a shutdown
Date Wed, 19 May 2004 07:51:36 GMT
As you all can see, I like to increase the traffic on this list :)

Ok, forget the second point on my list below. It's actually a bug
in Cocoon. Our keys have different values for the hash code when
the application is restarted, so they can't be found in the hash
map :(
But the first one seems to be true :)

Carsten 

> -----Original Message-----
> From: Carsten Ziegeler [mailto:cziegeler@s-und-n.de] 
> Sent: Wednesday, May 19, 2004 9:43 AM
> To: 'Turbine JCS Developers List'
> Subject: RE: Store surviving a shutdown
> 
> Ok, it seems that we have two problems:
> 
> - if only a few objects are cached, this is not persisted on shutdown.
>   It seems that there has to be a critical mass for this.
> - although on startup the objects are read (at least the log message
>   indicates that all keys are found), the keys are either not found
>   or do not match - this might be due to our custom keys we use, I
>   will further investigate.
> 
> Carsten 
> 
> > -----Original Message-----
> > From: Carsten Ziegeler [mailto:cziegeler@s-und-n.de]
> > Sent: Wednesday, May 19, 2004 8:39 AM
> > To: 'Turbine JCS Developers List'
> > Subject: RE: Store surviving a shutdown
> > 
> > Gosh, thanks Travis, you're right. My test case did wrote the data 
> > with a different class than it has been read with. Argh! Sorry!
> > 
> > I will try it again and have a look where the problem really lies.
> > 
> > Carsten
> > 
> > > -----Original Message-----
> > > From: Travis Savo [mailto:tsavo@IFILM.com]
> > > Sent: Tuesday, May 18, 2004 11:02 PM
> > > To: 'Turbine JCS Developers List'
> > > Subject: RE: Store surviving a shutdown
> > > 
> > > That would happen when the LRUMapJCS was written to disk,
> > and then the
> > > LRUMapJCS class file changed. Presently there's no good
> > solution for
> > > migrating from older versions of classes to new ones with 
> straight 
> > > Java Object Serialization.
> > > 
> > > My suggestion would be to delete your disk cache, as this
> > will force
> > > the new version of the class to be written out to disk. 
> > You'll need to
> > > do this any time your LRUMapJCS class changes (or any 
> classes being 
> > > serialized to disk for that matter).
> > > 
> > > If class migration is a requirement (i.e. you need to be able to 
> > > upgrade your JCS with LRUMapJCS changes without loosing your disk 
> > > cache), you might want to look into some of the Java XML
> > Serialization
> > > frameworks available, as I seem to have a vague memory of
> > one of them
> > > supporting class migration.
> > > It would be fairly trivial to create a new disk cache 
> which used it 
> > > instead.
> > > 
> > > -Travis Savo
> > > 
> > > 
> > > -----Original Message-----
> > > From: Carsten Ziegeler [mailto:cziegeler@s-und-n.de]
> > > Sent: Tuesday, May 18, 2004 1:46 PM
> > > To: 'Turbine JCS Developers List'
> > > Subject: RE: Store surviving a shutdown
> > > 
> > > 
> > > I think I found the problem now:
> > > 
> > > During reading the keys the following exception occurs in
> > readObject
> > > in
> > > IndexedDisk:
> > > 
> > > ClassCastException: local class incompatible: stream classdesc 
> > > serialVersionUID = 7888269624850553887, local class
> > serialVersionUID =
> > > 776964015449842672
> > > 
> > > And classname is org.apache.jcs.auxiliary.disk.LRUMapJCS
> > > 
> > > Hmm...
> > > 
> > > Carsten
> > > 
> > > > -----Original Message-----
> > > > From: Carsten Ziegeler [mailto:cziegeler@s-und-n.de]
> > > > Sent: Tuesday, May 18, 2004 4:15 PM
> > > > To: 'Turbine JCS Developers List'
> > > > Subject: RE: Store surviving a shutdown
> > > > 
> > > > Hi,
> > > > 
> > > > to complete the picture, attached is the configuration we use.
> > > > 
> > > > Carsten
> > > > 
> > > > > -----Original Message-----
> > > > > From: Carsten Ziegeler [mailto:cziegeler@s-und-n.de]
> > > > > Sent: Tuesday, May 18, 2004 2:31 PM
> > > > > To: 'Turbine JCS Developers List'
> > > > > Subject: RE: Store surviving a shutdown
> > > > > 
> > > > > Hi Aaron,
> > > > > 
> > > > > yes we are running the latest version from CVS and yes we
> > > > get the two
> > > > > files and they are both not empty.
> > > > > 
> > > > > But on startup the files are overwritten. Is there any
> > > > configuration
> > > > > for this perhaps?
> > > > > 
> > > > > Carsten
> > > > > 
> > > > > > -----Original Message-----
> > > > > > From: Aaron Smuts [mailto:aasmuts@wisc.edu]
> > > > > > Sent: Tuesday, May 18, 2004 2:25 PM
> > > > > > To: 'Turbine JCS Developers List'
> > > > > > Subject: RE: Store surviving a shutdown
> > > > > > 
> > > > > > The latest jcs version if shutdown properly, should write
> > > > two files
> > > > > > per region.  One called keys the other data.  One startup
> > > > it should
> > > > > > read the keys into memory and everything in the data folder
> > > > > should be
> > > > > > available just as before shutdown.
> > > > > > 
> > > > > > You need to make sure that the elements in the
> > regions are not
> > > > > > expiring also.
> > > > > > 
> > > > > > Are you getting the two files?  If not, did you build
> > > the latest
> > > > > > version of jcs from source?
> > > > > > 
> > > > > > Cheers,
> > > > > > 
> > > > > > Aaron
> > > > > > 
> > > > > > 
> > > > > > > -----Original Message-----
> > > > > > > From: Carsten Ziegeler [mailto:cziegeler@s-und-n.de]
> > > > > > > Sent: Tuesday, May 18, 2004 5:36 AM
> > > > > > > To: 'Turbine JCS Developers List'
> > > > > > > Subject: RE: Store surviving a shutdown
> > > > > > > 
> > > > > > > Just an additional info:
> > > > > > > It seems that the files are written properly on
> > > > shutdown, but on
> > > > > > > startup they are overwritten with empty files.
> > > > > > > 
> > > > > > > Carsten
> > > > > > > 
> > > > > > > > -----Original Message-----
> > > > > > > > From: Upayavira [mailto:uv@upaya.co.uk]
> > > > > > > > Sent: Tuesday, May 18, 2004 9:46 AM
> > > > > > > > To: turbine-jcs-dev@jakarta.apache.org
> > > > > > > > Subject: Store surviving a shutdown
> > > > > > > >
> > > > > > > > Hello, another Cocooner popping in for a visit!
> > > > > > > >
> > > > > > > > In our explorations of JCS, one thing I believe that
was
> > > > > > said about
> > > > > > > > it is that the store doesn't persist through a shutdown.
> > > > > > > >
> > > > > > > > Now, the current (slightly buggy) implemention within
> > > > > > Cocoon does. 
> > > > > > > > Is there any way to make it persists through a restart,
> > > > > > or to make
> > > > > > > > it configurable?
> > > > > > > >
> > > > > > > > The main usecase for Cocoon is running within a
> > > > servlet, where
> > > > > > > > arguably surviving a shutdown isn't crucial. However,
> > > > > > Cocoon can be
> > > > > > > > used from the command line to statically generate
web
> > > > > sites. For
> > > > > > > > this, a working persistent cache that survives
> > > > shutdown can be
> > > > > > > > invaluable. Each time you run it, it can check to
see
> > > > > > whether a page
> > > > > > > > in the cache is up-to-date, and if so, not bother
> > > > > generating the
> > > > > > > > page. This should be able to offer a great performance
> > > > > > improvement
> > > > > > > > (but didn't because our previous implementation of
a
> > > > persistent
> > > > > > > > store was slow). So you'd make me a happy man if you
> > > > gave me a
> > > > > > > > responsive persistent store that could survive 
> a shutdown.
> > > > > > > >
> > > > > > > > Regards, Upayavira
> > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > 
> > > > > 
> > > > 
> > > 
> > 
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> > > > > > > >
> > > > > > > 
> > > > > > > 
> > > > > > > 
> > > > > > 
> > > > > 
> > > > 
> > > 
> > 
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> > > > > > 
> > > > > 
> > > > 
> > > 
> > 
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> > > 
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