[Asterisk-code-review] res odbc: Remove connection management (asterisk[13])

[Mark Michelson]

Mark Michelson has posted comments on this change.

Change subject: res_odbc: Remove connection management
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Patch Set 3:

> If caching isn't in the picture, what improvements with PJSIP have
 > we seen with this patch? Has the thrashing on the bottleneck been
 > removed as a result of using the ODBC library's connection pooling?

I haven't been able to prove that the thrashing on the bottleneck has been removed. I've run side-by-side comparisons of the same SIPp scenarios (high cps scenarios), and I find no discernible difference on my development box with this patch applied and without it.

The problem is that I can't get the bottleneck to occur on my machine in the first place. I believe in the cases where the bottleneck showed itself, I/O on the machine in question was slower than would be expected. In order to simulate that, I believe I'd need to have a more complicated setup (such as having a remote DB server over a constrained network).

The best I can do right now as far as proof is an "on-paper" proof. The bottleneck previously had been that while one thread was performing a database query, other threads waiting to perform queries were blocking attempting to acquire the database connection's lock. By using independent database connections, that specific bottleneck is certainly eliminated. It is possible that locks within the database itself could cause a similar bottleneck, but that is currently not known, and as I mentioned previously, my test environment makes any sort of improvement difficult to prove.

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Gerrit-MessageType: comment
Gerrit-Change-Id: I37a84def5ea4ddf93868ce8105f39de078297fbf
Gerrit-PatchSet: 3
Gerrit-Project: asterisk
Gerrit-Branch: 13
Gerrit-Owner: Mark Michelson <mmichelson at digium.com>
Gerrit-Reviewer: Anonymous Coward #1000019
Gerrit-Reviewer: Joshua Colp <jcolp at digium.com>
Gerrit-Reviewer: Kevin Harwell <kharwell at digium.com>
Gerrit-Reviewer: Mark Michelson <mmichelson at digium.com>
Gerrit-Reviewer: Matt Jordan <mjordan at digium.com>
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