[OSM-dev] generate_tiles.py 15x speed-up on mac os x :: how to verify that postgres statistics are correctly disabled

Ceriel Jacobs cerieljacobs at gmail.com
Thu Feb 12 18:14:05 GMT 2009


In the search to speed up the slow generate_tiles.py (~ 37 tiles per  
minute) on Mac OS X 10.5.6 with MacPorts installation,
I found out with 'iofileb.d' & 'iofile.d' that much disk i/o was used  
by Spotlight.

After disabling spotlight things went faster. But there was still lots  
of unnesseary disk writing: postgres statistics.

Now I disabled statistics (I think) by changing /opt/local/var/db/ 
postgresql83/defaultdb/postgresql.conf while the postgres daemon was  
being stopped:
#track_activities = on
track_activities = off
#track_counts = on
track_counts = off
#update_process_title = on
update_process_title = off

After (re)starting postgres daemon, there is a major speed improvement  
(> 575 tiles / minute), but still some statistics writing is being done:
$ sudo iofileb.d
Password:
Tracing... Hit Ctrl-C to end.
^C
    PID CMD              KB FILE
    100 perl              4 ??/webmin/miniserv.pid #webmin
   1030 Python            4 ??/33481/21874.png
   1030 Python            4 ??/33481/21876.png
   1030 Python            4 ??/33481/21878.png
   1030 Python            4 ??/33481/21879.png
   1030 Python            4 ??/33481/21880.png
   1030 Python            4 ??/33481/21881.png
   1030 Python            4 ??/33481/21882.png
   1030 Python            4 ??/33481/21883.png
   1030 Python            4 ??/33481/21884.png
   1030 Python            4 ??/33481/21885.png
   1030 Python            4 ??/33481/21886.png
   1030 Python            4 ??/33481/21887.png
   1030 Python            4 ??/33481/21888.png
   1030 Python            4 ??/33481/21889.png
   1030 Python            4 ??/33481/21890.png
   1030 Python            4 ??/33481/21891.png
   1030 Python            4 ??/33481/21892.png
   1030 Python            4 ??/33481/21893.png
   1030 Python            4 ??/33481/21894.png
   1030 Python            4 ??/33481/21895.png
   1030 Python            4 ??/33481/21896.png
   1030 Python            4 ??/33481/21897.png
   1030 Python            4 ??/33481/21898.png
   1030 Python            4 ??/33481/21899.png
   1030 Python            4 ??/33481/21900.png
   1030 Python            4 ??/33481/21901.png
   1030 Python            4 ??/33481/21902.png
   1030 Python            8 ??/33481/21875.png
   1030 Python            8 ??/33481/21877.png
   1025 postgres        168 ??/global/pgstat.tmp

= 124KB for images versus 168KB for postgres in this (short) period of  
time.

Questions:
1. How  can I verify that I edited the correct postgresql.conf file,  
in other words how can I verify which postgresql.conf file is used by  
MacPorts daemon?

I would say by checking the process tree, and check which data  
directory is specified:
    103 	postgres 	/opt/local/lib/postgresql83/bin/postgres -D /opt/ 
local/var/db/postgresql83/defaultdb
       105 	postgres 	postgres: writer process
       106 	postgres 	postgres: wal writer process
       107 	postgres 	postgres: autovacuum launcher process
       108 	postgres 	postgres: stats collector process
       259 	postgres 	postgres: postgres gis [local] idle

2. Is it correct to think that when disabling statistics in  
postgresql.conf, no pgstat.tmp should be written to, or isn't it?

3. Or should I restart the server machine before these 'disabling  
statistics' changes become effective in postgres server?

~Ceriel




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