Hello We are using PostgreSQL 9.3.10 on RedHat (probably 6.x). The database is hosted by an internal service provider and we have superuser access to it over a PG client, e.g. psql, but not to the OS. For that reason we only have access to the log files indirectly using some of the built in system functions like pg_ls_dir, etc. Among other thing the database is the backend for a web application that expects a load of a some hundred users at a time (those are participans to online surveys that we use for computing economic indicators and access the system every month). The whole amount of people expected is above 5000, but we don't expect a too high concurrent access to the database. As mentioned a few hundreds at the beginning of the surveys. To be sure that we won't have problems with the peak times we created a load test using gatling that ramps up to 1000 users in 5 minutes in bunches of 10. At the beginning we had problems with the web server response that we were able to correct. Now we face problem with the max_connections limit of PostgreSQL. Currently it is set to the default of 100. We are going to look into it and either increase that limit or consider connections pooling. What bothers me however is that running a query on pg_stat_activity with a watch of 1 seconds never shows any value higher than 37 of concurrent active connections. SELECT count(*) FROM pg_stat_activity; watch 1; Due to that fact it took us quite a time to figure out that the bottleneck had become the database. We discovered it after looking into the log files (as mentioned above this is not very straightforward, in particular because the logs tend to become quite huge). I assume that the peaks of requests violating the limit happen between two calls of the query. Is there a better way to keep track of this kind of problems? I felt a bit weird not to be able to discover the issue sooner. And what would be a reasonable strategy to deal with the problem at hand? Increasing max_connections has repercussions on the configuration of work_mem (if I remember well) or on the other hand on the amount of physical memory that must be available on the system. On Thursday we are going to have a meeting with our DB hosting provider to discuss which improvement need to be made to meet the requirements of our applications (the web application mentioned is not the only one using the database, but is the only one where we expect such peaks). So I'd be very grateful for advice on this subject. Thank you. Regards Charles -- Swiss PostgreSQL Users Group c/o Charles Clavadetscher Treasurer Motorenstrasse 18 CH – 8005 Zürich http://www.swisspug.org +-----------------------+ | ____ ______ ___ | | / )/ \/ \ | | ( / __ _\ ) | | \ (/ o) ( o) ) | | \_ (_ ) \ ) _/ | | \ /\_/ \)/ | | \/ <//| |\\> | | _| | | | \|_/ | | | | PostgreSQL 1996-2016 | | 20 Years of Success | | | +-----------------------+ -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
