[opencms-dev] OpenCms 7.0.5 crashes with high load

Christian Steinert christian_steinert at web.de
Thu Mar 26 10:57:54 CET 2009

Nacho Fernández Orellana ha scritto:
> As for Alkacon's commercial module package I'm afraid right now the budget
> wouldn't allow that. I'll investigate about query cache possibilities in
> Oracle to see if I can get some improvement in that direction.
It seems that there is something like that in 11g, but I don't know if 
it fits exactly or if queries must be adjusted to make use of this.

Alternatively, if you have no other options, it might be worth to write 
your own CmsVfsDriver that extends the regular VfsDriver and takes care 
of caching results (you can configure the VFS driver to be used in 
opencms.properties). This should be doable but it needs to be done well 
and then you end up having to maintain this code when opencms is updated.
The tricky thing if you roll your own cache, as with any cache, is of 
course keeping the cache within a specified amount of memory (there 
should be libraries for that) and invalidating cached entries if the 
file system is updated. I have not seen Alkacon's caching module but it 
would make sense for them to integrate their caching as a custom 
CmsVfsDriver - maybe their accellerator is even the reason why a 
configuration option for CmsVfsDrivers exists.

I have considered creating my own caching VfsDriver but for our workload 
it might not really be worth the effort since the usage of MySql-based 
caching has given us quite a bit of breating space again.

Also, if you have pages that are visited frequently (who hasn't) try to 
cache these pages with FlexCache in memory and give them short 
invalidation times. For example, maybe you can get away with keeping a 
popular page or some expensive parts of it cached for one minute or half 
a minute, even if it is generated dynamically. Since opencms invalidates 
cached content, whenever things are published, it might also be ok, to 
just activate the cache and let opencms handle expiration automatically. 
Really try to think which parts of your pages are expensive and how 
often they really must be re-generated.

Best Regards

> Thank you again for all your insights into this issue (and your great
> general contribution to this list as well), I'm sure they wil be helpful for
> many other users too. Greetings,
> Nacho Fernandez.
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