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From Aaron Smuts <asm...@yahoo.com>
Subject Re: Indexed Disk Cache safe copying of files
Date Wed, 17 Jun 2009 20:50:38 GMT

Thanks.  I commented on JIRA.  

I'll have to reimplement the general idea without any JDK 1.4 dependencies. 

We need to think through the way updates are done.  If these will be shared, we'll have to
have some kind of lock, perhaps another file with the same name with a .lock suffix. . . 
. . .

Cheers,

Aaron



----- Original Message ----
From: Tore Halset <halset@pvv.ntnu.no>
To: JCS Users List <jcs-users@jakarta.apache.org>
Sent: Wednesday, June 17, 2009 4:35:11 PM
Subject: Re: Indexed Disk Cache safe copying of files

Hello.

I do this in my jcs cache. The items in the cache is 0-30MB each. The total volume is ~20GB.
Instead of the standard indexed disc cache, I use a file based cache. The key is converted
to a filename and each item is stored as a separate file. Several jvms can share the same
cache and the cache can be rsynced between nodes while running the application.

This setup might be slow for caches with lots of small objects, but it works very well with
my setup.

The source code is attached to this issue:
https://issues.apache.org/jira/browse/JCS-58

To be able to hold as many objects as possible in ram without getting OutOfMemoryException,
I use this cache with a soft reference cache.
https://issues.apache.org/jira/browse/JCS-54

Regards,
- Tore.

On Jun 17, 2009, at 10:23, Silvano wrote:

> Since we have a large cache that needs significant time to be populated, we need to be
able to copy the files of the regions configured as Indexed Disk Cache between different installations.
> We believe this can be done safely if we turn off the jvm, but we would need to copy
safely the files while the jvm is running. However it seems that the key files are written
only when you turn off the jvm (at least the size changes when we turn off the jvm, so we
suspect that they are not synchronized to disk in normal operations).
> 
> We can make sure at application level that nobody writes in the cache during the file
copy process, but is this sufficient?
> 
> Can anybody recommend a solution to this issue?
> 
> Best regards,
>   Silvano.
> 
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