--- I wrote:

> I have gotten the chat to work better (= less deadlocks / errors) by
> doing the following (that might help others if they face the same
> kinds of problems):

Just FYI I thought I would mention that the chat currently gets ca
400000 page requests per day which translates to 277 requests per
minute = 4,6 requests per second. Each request generates a minimum of
6 sql SELECT/INSERT queries to 3 different tables (this could still be
optimized), but might in some rare cases do up to 15 queries depending
on what the user does.

As a reslut, the chat generates a mimimum average of ~28 sql queries
per second (=2419200/day) to the FB database.

(note: that this is the average, during peak hours it's probably at
least twice as high)

Don't know if this would be considered "heavy" use, but avoiding
deadlocks require that some thought is put into the code...

- Mikael