In the source lib/srdb1/* some kind of pooling is used.
When kamailio needs a database connection, the cmp_db_id function
checks to see if there is already a database connection with the
exact same params (username, database, server etc..).
According to the PQ library every proces / thread should have it's
own database connection.
The db_postgres is setup to use asynchronous I/O with the PQ
library.
So when two threads are using the same database connection it is
possible that,
the resultset from a query of thread A is returned to thread B.
The cmp_db_id function in lib/srdb1/db_id.c does _not_ check the
PID.
I've created a small patch to fix the problems mentioned above.
The changes are made in lib/srdb1/* files
So if you apply them, it will be active for _every_ database module.
Maybe it's not needed for the mysql database,
but I *assume* it will not break when used on a mysql database. (not
tested)
Maybe you will get a bit more database connections, but that depends
on which modules you're using.
What did I do:
Added pid to the db_id struct.
During initialization the pid is saved into the db_id struct.
In cmp_db_id the pid is also checked when searching for a
database connection to be reused.