#18135: Sleeping Database Connections on Startup with MySQL
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Reporter: Mnewman | Owner: aaugustin
Type: Bug | Status: assigned
Component: Database layer | Version: 1.4
(models, ORM) | Resolution:
Severity: Normal | Triage Stage: Design
Keywords: MySQL | decision needed
Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Comment (by aaugustin):
Replying to [comment:26 Mnewman]:
> So what happens on sites, like I have, that run millions of concurrents?
I need hundreds of thousands threads to properly scale. I cannot afford a
relational database that requires that many open "sleeping" connections.
Exaggeration doesn't help your credibility. No one's running hundred of
thousands of Django workers connected to a MySQL database without a
pooler. And the topic of this ticket isn't persistent connections. At the
moment, they're just a proposal, open for discussion on the mailing list.
----
Back to the topic.
I missed a use case in my previous comment: it's possible to have a MySQL
database that's only occasionally hit by workers, especially if it isn't
the primary database. Such a database could support fewer simultaneous
connections than the total amount of workers.
In the current codebase, the only place that uses the MySQL server version
is `sequence_reset_by_name_sql`, and this function is only used by the
tests. It appears that it was called at import time in previous versions
of Django, but that isn't true any longer.
One could argue for keeping this code in case future versions of Django
introduce MySQL-version-dependent code that's evaluated at compile time,
but in general, unnecessary code hurts maintainability.
--
Ticket URL: <https://code.djangoproject.com/ticket/18135#comment:27>
Django <https://code.djangoproject.com/>
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