[sakai2-tcc] Site caching

[Berg, Alan]

Hi TCC,


Site caching is currently broken in Sakai 2.8. David Hainies reported this in: https://jira.sakaiproject.org/browse/KNL-652


And for specific tuning information for a partial solution in https://jira.sakaiproject.org/browse/KNL-658


Quote:” Site caching is broken in the K1 kernel 1.1.9 release. Sites objects themselves are cached but when sites are evicted from the site cache the secondary, in memory, caches for tools, pages, and groups are not cleaned up, the references to the objects remain and those objects can not be garbage collected. Over time this leads to large numbers of objects that won't be used but will consume memory. At Michigan, after not restarting Sakai for a couple of weeks we ended up with almost 2GB of memory devoted to the site cache. That caused long periods of fruitless garbage collection and a degradation of service.

The problem is avoided in the short run by restarting Sakai instances or by manually clearing the caches with the Admin memory tool. “



I believe David Howitz has placed the partial solution in production at UCT and has reported no issues. However, there needs to be more testing and perhaps refinement of the patch. The code is currently in trunk.


My suggestion is that we merge what exists into the next QA tag. Seth's QA server is already under consistent low level load from a Jmeter script, after a week with the new tag I could review the servers logs for Exceptions. When I have time I can then perform a more vigorous analysis or stress test, if not perhaps UMICH.


Both David Haines and David Howitz know the technology better than I, so if you have questions I will leave it to them to reply.

Alan

Alan Berg
QA Director - The Sakai Foundation

Senior Developer / Quality Assurance
Group Education and Research Services
Central Computer Services
University of Amsterdam

http://home.uva.nl/a.m.berg
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