Re: libpq connection status and closed fd

2014-09-22 10:42 GMT+04:00 Daniele Varrazzo <daniele(dot)varrazzo(at)gmail(dot)com>:

> Hello,
>
> a psycopg user is reporting [1] that the library is not marking the
> connection as closed and/or bad after certain errors, such as a
> connection timeout. He is emulating the error by closing the
> connection fd (I don't know if the two conditions result in the same
> effect, but I'll stick to this hypothesis for now).
>
> [1] https://github.com/psycopg/psycopg2/issues/263
>
> Testing with a short C program [2] it seems that indeed, after closing
> the fd and causing an error in `PQconsumeInput`, the connection is
> deemed in good state by `PQstatus`. A similar test gives the same
> result after `PQexec` is attempted on a connection whose fd is closed
> (tests performed with PostgreSQL 9.3.5).
>
> [2] https://gist.github.com/dvarrazzo/065f343c95f8ea67cf8f

Why are you using close() instead of PQfinish()?

>
>
> Is this intentional? Is there a better way to check for a broken
> connection?
>
BTW, PQsocket() returns -1 after PQfinish().

>
> If we mark the connection as closed every time `PQconsumeInput`
> returns 0 (or `PQexec` returns null, which are the two code paths
> affecting psycopg) would it be too aggressive and cause false
> positives?
>
> Thank you very much.
>
> -- Daniele
>
>
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--
// Dmitriy.