Submitted by : simon at: 2003-10-26T21:32:15+00:00 (14 years ago)
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Someone created an issue on my wiki, and as a subscriber, I saw three emails:

Both issues (TitleA and TitleB) were created within the same minute.

Can you explain how two issues can be created with the same issue number and how one of them get's renamed? Presumably its caused by the two requests happening almost simultaneously, the get of the current number not being part of a critical section and some post-creation fix-up process sorting it out. If this is what happened, how about some explanatory note in the mailout text or subject line to let the subscriber know.


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Re: [IssueNo0545? Why was a new issue renumbered/renamed automatically?] mail transaction-awareness problem --Simon Michael, 2003/07/03 09:25 GMT reply

> Can you explain how two issues can be created with the same issue number
> and how one of them get's renamed? Presumably its caused by the two
> requests happening almost simultaneously, the get of the current
> number not being part of a critical section and some post-creation
> fix-up process sorting it out.

Interesting.. now that you mention it I see how that might happen. The zope database transaction fails due to a conflict error, and retries. (This is a feature of the ZODB, nothing to do with Zwiki.) Meanwhile another issue creation succeeded and so zwiki ends up using the next higher issue number.

A similar problem is occasional duplicate mail-outs due to a comment transaction being retried.

The general problem is that mail isn't aware of ZODB transactions. Zwiki/zope shouldn't send mail until the transaction succeeds. I'm not sure how to do that, or even how Zwiki can know that a retry happened.

property change --SimonMichael, 2003/08/03 00:12 GMT reply
Title: IssueNo0545 Why was a new issue renumbered/renamed automatically? => IssueNo0545 zodb conflicts can cause duplicate issues

property change --SimonMichael, 2003/08/03 00:19 GMT reply
Severity: normal => minor

correction --simon, Wed, 28 Oct 2009 11:20:09 -0700 reply
Name: #545 zodb conflicts can cause duplicate issues => #545 possible to get duplicates when creating an issue

I think non-transaction-aware mail sending may not be the explanation here, since two issue pages were created. A zodb conflict shouldn't cause that.

And whether it's the same issue or not, I had this happen to me just now, two identical consecutive issues were created in the tracker.