"No DB handles" workaround

[Brian Julin]

> Pete Ashdown wrote:
 
> Our SQL server is a 24 core, 32GB, SSD backed server with very light
> loads.  A slowquery log showed nothing of interest, so we started
> looking in other directions.
> 
> What we found is that if the thread pool max_servers > sql num_sql_socks
> this error will occur.  I haven't looked at the code, but I am guessing
> that it is locking one SQL socket per thread, and if you have more
> threads than sockets, then you will start seeing this error.  We set
> max_servers and num_sql_socks both to 15 and we haven't seen the error
> since.

Well, your database was obviously not fast enough to outpace the rate
at which FR can put requests into threads :-)

IN 3.0 the num_sql_socks is replaced by the more generic "max" option
in the connection pool config.  In case this is still an issue there for anyone.