On Mar 5, 2007, at 3:40 PM, Perrin Harkins wrote:
Look for things that use locking. Anything that updates a file or a
database row. In particular, look for things that do this and would
happen on every type of request that you've seen hanging so far.
As a note, you could run into blocks/locks/stalls from foreign keys.
I recently had this code in my system
handle 1- select * from account where id = 1;
handle 2- update visit set visit_count= visit_count+1 where
account_id = 1; # account_id fkeys on account
it took me forever to realize why my system kept locking. the select
+ transaction on handle 1 was getting an exclusive lock, and the
update was queued , trying to do an internal select on the fkey for
integrity checks
the moral: db lock problems can happen where you least expect them
// Jonathan Vanasco
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