Re: [HACKERS] statement_timeout is not working as expected with postgres_fdw

On Thu, May 4, 2017 at 1:04 PM, Amit Kapila <amit.kapila16@gmail.com> wrote:
> On Thu, May 4, 2017 at 10:18 PM, Robert Haas <robertmhaas@gmail.com> wrote:
>> On Thu, May 4, 2017 at 12:18 PM, Amit Kapila <amit.kapila16@gmail.com> wrote:
>>> As soon as the first command fails due to timeout, we will set
>>> 'abort_cleanup_failure' which will make a toplevel transaction to
>>> abort and also won't allow other statements to execute.  The patch is
>>> trying to enforce a 30-second timeout after statement execution, so it
>>> has to anyway wait till the command execution completes (irrespective
>>> of whether the command succeeds or fail).
>>
>> I don't understand what you mean by this.  If the command doesn't
>> finish within 30 seconds, we *don't* wait for it to finish.
>>
>
> + /*
> + * Submit a query.  Since we don't use non-blocking mode, this also can
> + * block.  But its risk is relatively small, so we ignore that for now.
> + */
> + if (!PQsendQuery(conn, query))
> + {
> + pgfdw_report_error(WARNING, NULL, conn, false, query);
> + return false;
> + }
> +
> + /* Get the result of the query. */
> + if (pgfdw_get_cleanup_result(conn, endtime, &result))
> + return false;
>
> The 30 seconds logic is in function pgfdw_get_cleanup_result, can't
> the command hang in PQsendQuery?

Sure.  I thought about trying to fix that too, by using
PQsetnonblocking(), but I thought the patch was doing enough already.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company