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From Paul Spangler <paul.spang...@ni.com>
Subject Re: [PATCH 57300] mod_session save optimization
Date Mon, 14 Sep 2015 17:53:22 GMT
On 8/20/2015 4:58 PM, Paul Spangler wrote:
> Hello,
>
> The bug report contains a more detailed explanation of the patch, but
> there are some points I thought might lead to some discussion.
>
> First a quick summary of the issue: mod_session writes out the session
> every request even if there aren't any changes to the data. This makes
> some sense when the session has a max age and the expiry value needs to
> be refreshed. However, there isn't likely to be much benefit in
> repeatedly refreshing the expiry by a few milliseconds, possibly
> generating database traffic each time. This patch proposes a new
> directive to define an interval of time where the expiry doesn't need to
> be refreshed if there are no session data changes.
>
> 1. We had a hard time coming up with a name for the directive. The patch
> goes with SessionExpiryUpdateInterval, being the interval of time that
> may pass before updating the expiry value is required. I don't know if
> there are any existing directives with a similar function that we should
> mimic instead.
>
> 2. The patch includes a behavior change independent of the new directive
> when using sessions without a max age: if the data hasn't changed, don't
> write out the session. Most noticeably, this means new sessions that
> never get data are discarded without being saved.
>
> 3. I wasn't sure how best to add tests for a new directive since the
> test server won't start if the directive is missing. The patch that
> includes the test changes look for the 2.5 version to know the new
> directive is there, and will require a modification if/when the
> directive is back-ported to 2.4 to enable the new tests.
>
> https://bz.apache.org/bugzilla/show_bug.cgi?id=57300
>
> Thanks for your consideration.

Quick ping on this.
-- 
Paul Spangler
LabVIEW R&D
National Instruments

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