Re: BUG #10141: Server fails to send query result.

Greetings,

* molind(at)gmail(dot)com (molind(at)gmail(dot)com) wrote:
> While it works it opens 1 db connection per thread (8 threads) and queries
> all tiles from list 25k tiles in average. 5 queries per tile. During map
> generation usually 2 threads stuck in idle state.
>
> http://i.stack.imgur.com/VUU4O.png

This only shows what's happening server-side.

> Look at the last row. Query started. We have a timestamp, then it finished
> and changed state to idle, and we have timestamp of that moment. Everything
> looks ok, except console app which waits answer from server inside
>
> PGresult *res = PQexec(conn, query);
>
> It waits for query results from server. And I can't find why server thinks
> that job is done and app says that there was no answer from db yet.

Can you provide a small example test case which illustrates this? You
didn't provide your code, so it's really difficult to have any idea
what's going on.

What version of libpq is being used and on what platform? Are you using
SSL at all for your connection?

> I added PQtrace for each thread and wait for stuck thread. There is trace:
>
> >From backend> D
> >From backend (#4)> 139891
> >From backend> D
> >From backend (#4)> 139891
> >From backend> D
> >From backend (#4)> 139891
> >From backend> D
> >From backend (#4)> 139891
> >From backend> D
> >From backend (#4)> 139891
> >From backend> D
> >From backend (#4)> 139891
>
> Seems problem somewhere inside PostgreSQL. It tries to send result but
> fails.

I don't see anything here which shows that to be the case. Is the TCP
connection still fully ESTABLISHED on both sides? What's in the
middle..? Could you have a firewall or IDS which is dropping the
connections?

Thanks,

Stephen