The patch is approved, and the issue closed.

Cheers,
Gunnstein


On Fri, Aug 13, 2010 at 11:21 AM, Gunnstein Lye <[email protected]> wrote:
> Thanks for the detailed description! I have uploaded a fix at:
> http://issues.ez.no/17096
>
> This is pending internal review.
>
> Gunnstein
>
>
>
> On Wed, Aug 11, 2010 at 9:51 PM, Peter Keung <[email protected]> wrote:
>> Hi SDK,
>>
>> We've experienced the same cache problem on two large eZ DFS cluster
>> setups. The first request for a page loads successfully and quickly but
>> subsequent requests take a long time to respond. Then another page will
>> be quickly loaded, but subsequent requests again hang. This cycle only
>> needs to repeat a few times until server performance is severely
>> affected and a busy server will crash.
>>
>> How to reproduce the problem:
>> - Make successive page requests to a node that the current user does not
>> have the permission to view, resulting in an access denied (kernel 1)
>> error; for example "/users"
>> or
>> - Implement a server-side redirect operator within a full view template.
>>
>> Analysis:
>>
>> The first page request starts cache generation. However, in both of the
>> above scenarios, it appears that viewcache generation is not properly
>> completed with a full view of a node. For example, with the server-side
>> redirect operator, the request is redirected in the middle of viewcache
>> generation. And the "access denied" page, although is standard eZ
>> Publish functionality, doesn't seem to conform to what the eZ DFS cache
>> generation process is expecting. Thus, subsequent page requests are
>> waiting for a cache file to generate, but that cache file has already
>> stopped being generated.
>>
>> If you inspect the ezdfsfile table, you will find an entry similar to:
>>
>> INSERT INTO `ezdfsfile` VALUES
>> ('var/tao/cache/content/tao/5-9b676f6081843e14c8d5682a3647f38f.cache.generating',
>> 'var/tao/cache/content/tao/5-9b676f6081843e14c8d5682a3647f38f.cache.generating',
>> '588803514a4a26a99554e43762fa66cf', , , 0, 1281244184, 0, 0);
>>
>> Manually removing that entry solves the problem for one more page load,
>> but of course, the same entry will return and repeat the hanging cycle
>> all over again.
>>
>> Unsuccessful solutions:
>>
>> - Using {cache-ttl} blocks at the top of the full view template to "turn
>> off" viewcache. This still happens within what I'm calling the
>> "viewcache context" and thus the problem still occurs.
>>
>> - Using ViewCacheTweaks (site.ini), as this is only possible per node
>> and not feasible to maintain when needed to be applied per section, per
>> class, and similar.
>>
>> - Setting the NonExistantStaleCacheHandling values (file.ini) to
>> "generate" instead of "wait" appears to have no effect.  Even if it did
>> help, it might affect site performance unintentionally if you only
>> wanted this setting to apply to certain nodes.
>>
>>
>> Is there a way to forcibly complete or end cache generation in an
>> operator in those cases within the current eZ DFS setup?
>>
>> Otherwise this seems like a critical bug - but we would like to get an
>> opinion on this before we proceed.
>>
>>
>> Peter
>> --
>> Sdk-public mailing list
>> [email protected]
>> http://lists.ez.no/mailman/listinfo/sdk-public
>>
>
>
>
> --
> Gunnstein Lye
> Product Support Engineer
> [email protected] | www.ez.no | eZ Systems
>



-- 
Gunnstein Lye
Product Support Engineer
[email protected] | www.ez.no | eZ Systems
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