#19519: Django fails to close db connections at end of request-response cycle
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Reporter: amosonn@… | Owner: aaugustin
Type: Bug | Status: assigned
Component: Database layer | Version: master
(models, ORM) | Resolution:
Severity: Release blocker | Triage Stage: Ready for
Keywords: connection, | checkin
managment, closing, mysql, | Needs documentation: 0
innodb, signal, generator | Patch needs improvement: 0
Has patch: 1 | UI/UX: 0
Needs tests: 0 |
Easy pickings: 0 |
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Comment (by akaariai):
I am wondering if pushing the request_finished signal to late stages is
actually safe to do. Question no. 2 from pep 3333
[http://www.python.org/dev/peps/pep-3333/#questions-and-answers] says
that:
{{{
If we supported only the iteration approach, then current frameworks
that assume the availability of "push" suffer. But, if we only support
pushing via write(), then server performance suffers for transmission
of e.g. large files (if a worker thread can't begin work on a new
request until all of the output has been sent). Thus, this compromise
allows an application framework to support both approaches, as
appropriate, but with only a little more burden to the server
implementor than a push-only approach would require.
}}}
To me this suggest it is possible a different thread will finish the
request and/or there is another request processed at the same time by the
same thread. This would mean that we could be closing connections for
different threads or different requests. I hope I am 100% wrong here.
If the above is the case, this is going to get a lot more complex. The
connection handling is bound to threads, not requests. What we could do is
detach the connection from the thread at the old request_finished point,
and then when the request is actually finished (the new request_finished
point) we could close the connection.
--
Ticket URL: <https://code.djangoproject.com/ticket/19519#comment:14>
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