I have been stonewalled by an interesting problem on a D7 site. Essentially the cache_menu table was getting very large but not just in items (6300 odd) some of the items are enormous.
Its a new record for me, one of the items is 1.24 mb and 26 of them are between 800k and 1mb.
The site went down when it was being git with slightly elevated traffic, its running on a load balanced AWS cluster with RDS at the back, there's no lack of resources for a 20 simultaneous connections site.
i truncated the cache_menu and regenerated everything by browsing the site and all but a few of the items are gone now but there are still the 1.2mb one and a handful of the 800kb ones.
I followed this link - http://drupal.org/node/1234830 from here Huge cache_menu table and it appears that this particular issue has been resolved for 7.13+ so i am thinking its something architectural going wrong.
There's no core hacks, we've got an impressive search system using a logic server network (running on SOLR externally) that does hook into taxonomy terms. The site is essentially a portal of links.
Could someone give me some pointers on where to start track this issue down?
edit: CID/sizes in cache_menu, query:
SELECT cid, LENGTH(`data`)/1024 as `size KB` FROM cache_menu WHERE LENGTH(`data`)/1024 > '300' ORDER BY `size kb` DESC;
links:management:tree-data:en:ec99d3452fef1ede622e66c68ba908b1dad455aa71f5e68648aeec6488b89c88 1094.2188 links:main-menu:all-cid:0:1:en 839.4873 links:main-menu:tree-data:en:ec99d3452fef1ede622e66c68ba908b1dad455aa71f5e68648aeec6488b89c88 815.6230