Re: [Webmacro-devel] Bad interaction with TimeLoop and cache time s?

[Lane S. <la...@op...>]

The api docs are really good at a discussion. Also, there is a 
discussion on the wiki site. Sometimes I refer to it as a VeryFastCache 
because the cache is immutable and therefore can be used unsynchronized.

It is pluggable drop. I have been using it for one year without error.

-Lane

Jeff Cowan wrote:

>Lane, thanks for the info. We'll work it into the next set of tests that we
>do.
>
>Can you point me at some documentation about how the
>GenerationalCacheManager works or what it's key / differentiating features
>are?
>
>Regards,
>Jeff
>
>-----Original Message-----
>From: Lane Sharman [mailto:la...@op...]
>Sent: Tuesday, January 14, 2003 8:08 PM
>To: Jeff Cowan
>Cc: 'web...@li...'
>Subject: Re: [Webmacro-devel] Bad interaction with TimeLoop and cache
>times?
>
>
>Hi Jeff,
>
>One of the many beauties of WebMacro is pluggability.
>
>About six months ago, we wrote a pluggable interface for the caching 
>after some really hot debate about synchronization. I have been using 
>exclusively an alternative cache manager which stems from my early days 
>writing VM paging and kernel systems. It is a generational caching 
>manager which can be configured as follows in webmacro.properties:
>
>==========================
>CachingProvider.template.CacheManager: 
>org.webmacro.resource.GenerationalCacheManager
>CachingProvider.url.CacheManager: 
>org.webmacro.resource.GenerationalCacheManager
># Set reloading to true since we are in development mode by default.
>GenerationalCacheManager.*.ReloadOnChange: true
># The refresh rate for incorporating changes to the mutable image
>GenerationalCacheManager.*.RefreshRate: 1000
>==========================
>
>Would you mind copying the above into your WebMacro.properties file and 
>seeing if you get some better performance or more control over your 
>memory utilization and let me know. (Change the last parameter measured 
>in millis to extend your mileage :).
>
>Gracie,
>
>Lane
>
>Jeff Cowan wrote:
>
>  
>
>>Hello all. My name is Jeff and I work with Glenn Shute at Altavista. He
>>suggested I drop a note here about something I've been looking at in
>>WebMacro. We're running WM 1.0.1 still, so maybe this is already fixed or a
>>warning has been put out already.
>>
>>I observed during some tests (memory profiling) that some templates were
>>being parsed repeatedly when they should have already been cached. I
>>    
>>
>checked
>  
>
>>my cache timeout settings in WebMacro.defaults. They are:
>>
>>SMapCacheManager.*.ExpireTime: 600000
>>SMapCacheManager.*.ReloadOnChange: false
>>
>>So, I would expect that once a template was acquired successfully, it
>>    
>>
>should
>  
>
>>be cached for 10 minutes. Looking more deeply, it appears that the TimeLoop
>>class that is responsible for purging the template cache of stale templates
>>has 600 periods of 1000ms each (again, 10 minutes).
>>
>>Setting LogLevel.resource to DEBUG, I observed that the template would be
>>aquired, cached and subsequently deleted from the cache almost right away.
>>It appears that when the period to run the task in is being computed in my
>>particular case, it is possible that the period in question is the one that
>>is about to run right at that moment. This would only happen in the case
>>where the periods corresponded to the ExpireTime, due to modulo arithmetic.
>>Eventually, if I continue reloading the page, all the templates get cached
>>successfully. This kind of error is a subtle timing issue, so the results
>>are different every time. 
>>
>>In our case, we can change the ExpireTime to 599000 and that seems to fix
>>it. I understand that this isn't really a bug. Just thought you might be
>>interested.
>>
>>Regards,
>>Jeff Cowan
>>Altavista Company
>>email: jeff <d o t> cowan <a t> av <d o t> com
>>
>>
>>
>>
>>
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>> 
>>
>>    
>>
>
>  
>

-- 
Lane Sharman
http://opendoors.com Conga, GoodTimes and Application Hosting Services
http://opendoors.com/lane.pdf BIO