Hi all,
I am trying to work out why a piece of software, Mapnik, is executing
slowly. All it is doing is loading a config file which causes about
12 preparation queries (i.e. with LIMIT 0) to be executed. I can see
from pg_stat_statements these only take ~1ms in their totality.
So next I ran "perf record -a -g sleep 0.4" and quickly loaded my PHP
page to start the process (I am interfacing with mapnik via a PHP
Extension), this is a sample of the result:
https://cloud.githubusercontent.com/assets/4375326/14836015/08b0a8b4-0c05-11e6-96e5-f1836497cdfe.png
The PHP page returns in ~60ms (well within the 400ms used for the perf
recording). If possible, please can anyone with more familiarity with
perf and Postgres tell me whether the result of the recording looks
healthy?
I am wondering if there is some problem with the way in which Mapnik
is implementing libpq -- I already moved from Mapnik 2.2 because it
was effectively DOSing Postgres by leaving client connections open.
Any help would be greatly appreciated.
Kind regards
Peter
