I found the cause of my issue.
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.
With kind Regards, Robert Verspuy