Bug: Multiple rows in a function may cause a problem

[capt4ce]

Description

Based on the simulation in a simple gist https://gist.github.com/capt4ce/311e443567792d6612eec90631efb981, it's found that if there are 2 executions of sql.DB.Query() in a function and the result.Close() of both of them using defer, it may risk DB deadlock.

Steps to reproduce

Try running the gist, the it will stuck after all the connections are used.

Expected behavior

The rows need to be closed well to avoid DB deadlock.