hmm.. I found this in apache2/error.log when I select the problematic product.
"....PHP Fatal error: Allowed memory size of 536870912 bytes exhausted (tried to allocate 130968 bytes) in /var/www/lib/Zend/Date/DateObject.php on line 479.."
It looks like to be problem with a date attribute. I checked attributes of the product but couldn't see any problem... how do I find out where the problem is? I also suspect the problem may not be related to this product too...
This is the point where you run out of free memory to allocate. It's just the last straw that overloads the camel and doesn't necessarily mean that DateObject is the culprit (even though it could be).
Usually the real reason has something to do with collections, or $entity->loads inside loops or something along these lines. I know I'm being somewhat vague, but memory leaks are like this -- hard to track down.
Thank you very much for your reply.
I spent hours to isolate the problem by trial-and-error, and finally managed to identify the problem is related to a custom tab setting in the product view of the theme I am using. As you have also mentioned, it is very difficult to track down the cause, so I have disabled the problematic setting to avoid the problem.
I am new to magento.. not sure how I can modify the phtml file to write deubg message (probably to system.log?)
Thanks a lot.
Good work! It's always pleasure to see folks who instead of whining and demanding freebies roll up their sleeves and find out what wrong.