[Twisted-Python] OT - adbapi, connection timeouts, mysql - OT
p.mayers at imperial.ac.uk
Tue Aug 25 11:25:35 EDT 2009
Phil Christensen wrote:
> On Aug 24, 2009, at 9:14 PM, Garret Heaton wrote:
>> On Mon, Aug 24, 2009 at 3:53 PM, Phil Christensen <phil at bubblehouse.org
>>> I feel like I can think of any number of ways running the same
>>> series of queries twice would be a bad thing. I have some very
>>> important queries that are run inside a interaction because they do
>>> a series of operations in sequence. I can't use transactions
>>> because my tables are MyISAM.
>>> Perhaps I'm jumping at shadows, but automatic re-querying just
>>> seems dangerous to me. Only the particular application knows when
>>> it's safe.
>> This is very true, and I should have mentioned it in my reply. Re-
>> running queries is only possible when you know your application can
>> do it safely.
>> How would you solve the issue of a lost connection in your case?
> Honestly, I have never actually solved it. I pretty much only write
> webapps these days, so when a ConnectionLost happens, it just
> propagates up the stack and displays an error to the user. Not ideal,
> by any means.
It's hard to apply in the general case, but I like the way Zope handles
this using the per-request transaction machinery.
Basically, if any processing generates a "retry"able exception, all
transactions attached to the request are rolled back and the entire
This works really, really well for HTML<->SQL CRUD apps.
I can't see how Twisted could support that currently, given the
deferToThread == 1 transaction nature of adbapi.
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