Applications that leak connections

[Jonel Rienton]

you are perfectly right, fixing the source of the problem is the best way to
fix this. i always make it a habit to close my connections as soon as i'm
done with it. if foxpro won't do it for you, you have to manage your own
resources, always a good practice for unmanaged applications.

i suggest you parse your code for all lines that opens the connection and
close it where it's not needed anymore.

good luck.

regards,


On Thu, 03 Feb 2005 18:27:46 -0500, Paul Tillotson wrote

> Does anyone have any useful info about dealing with applications
> which "leak" connections, eventually causing "connection limit
> exceeded for non superusers?"
>
> Obviously fixing the app is the best choice, but I have a feeling
> that this is going to recur again and again since the app is poorly
> maintained but still under active development (code base too large
> for the developer assigned to it). The developer is likely to
> accidentally cause connection leaks in the future.
>
> This problem is also very easy to cause because doing this:
>
> c = sqlconnect("database")
> c = sqlconnect("database")
>
> Causes TWO connections to be made, and the first connection made is
> now
> (as far as I can see) impossible to close without closing the
> application. The language (Visual Foxpro) does not garbage collect
> connections and so any connection whose handle is lost still takes
> up one of the slots.
>
> On the server side, I can detect this condition using ps -A or lsof;
> but I have not thought of a good solution to use when this is
> noticed. One possibility is to just shut down the database and
> restart it when this happens. I did some research into finding out
> if it was possible to break a specific TCP connection (this is linux
> 2.6 kernel--platform specific tools/commands ok). For example,
> could I use hping to break the connections?
>
> Does anyone know a safe way to shutdown just one backend (if it is
> idle)?
>
> Another possibility that I can think of is per ip address connection
> limits. How hard would that be?
>
> Paul Tillotson
>
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--
Jonel Rienton
[url]http://blogs.road14.com[/url]
Software Developer, *nix Advocate


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[Neil Conway]

Paul Tillotson wrote:

> Does anyone know a safe way to shutdown just one backend

Sending it a SIGTERM via kill(1) should be safe.

-Neil

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