Ceiling limit to connection.queries

[miohtama]

If you run Django in standalone mode, debugging enabled, all SQL queries get logged. Eventually in long running processes this will exhaust the process memory. This is "known feature" and the current solution is to have FAQ about the issue. When something leaks memory, people might not look FAQ as the first resolution: ​http://blog.redinnovation.com/2008/03/07/debugging-django-memory-leak-with-trackrefs-and-guppy/

This all could be solved by simply making connection.queries working as FIFO queue and store max. 100 queries. No more "memory leaks", ever.

[Karen Tracey <kmtracey@…>]

Capping connection.queries was proposed and rejected in #3711. Looks like that one is still open for getting a note about the behavior into the official docs.

[Aymeric Augustin <aymeric.augustin@…>]

In cfcca7ccce3dc527d16757ff6dc978e50c4a2e61:

Fixed #3711, #6734, #12581 -- Bounded connection.queries.

Prevented unlimited memory consumption when running background tasks
with DEBUG=True.

Thanks Rob, Alex, Baptiste, and others.