Mmm... I see. That was my understanding in the first place. At that time I did the maths, I had 10 apps, each one using a pool_size of 3. In postgresql.conf max_connections was set to 80. However this morning, with those numbers, almost every of my websites was throwing intermitent HTTP 500 errors, and the error tickets were all the same: FATAL: remaining connection slots are reserved for non-replication superuser connections.
Right now, I have almost 13 websites, all of them with pool_size in 3, and max_connections in 80. However, if I check the table "pg_stat_activity" I can see 65 connections, and I can see there is 5 connections per app. I've tried even setting pool_size to 1 for one of the apps, restarted database server and webserver, but again I check pg_stat_activity and I see 5 connections for that app. ¿Am I missing something too ovbious? 2014-11-28 14:25 GMT-03:00 Niphlod <niph...@gmail.com>: > > > On Friday, November 28, 2014 3:31:02 PM UTC+1, Lisandro wrote: >> >> I go back to this thread because today I ran with the same problem: >> postgresql reaching max_connection limits and, therefor, some of my websites >> throwing intermitent HTTP 500 errors (because web2py couldn't connect to the >> database). >> >> To remind, we are talking of a VPS with multiple instances of web2py >> running, all of them serving the same web2py app, each one connecting to a >> different postgresql database (however the database structure is the same >> accross all the databases). Each web2py instance is served by a lighttpd >> virtual host through fastcgi. Each virtual host (that is, each web2py >> instance) receives a different volume of traffic (that is obvious, they are >> different websites with different public). >> >> The original problem (the one that caused I post this question in the >> first place) was that the postgresql database server was reaching the >> "max_connections" limit and, in consecuence, some of the websites were >> throwing intermitent HTTP 500 errors (web2py couldn't connect to database). >> >> Then, the user oriented me with "pool_size" parameter of DAL constructor. >> Thanks again! >> I've been reading the web2py documentation about pooling [1] and I notice >> that it says that "When the next http request arrives, web2py tries to >> recycle a connection from the pool and use that for the new transaction. If >> there are no available connections in the pool, a new connection is >> established". >> So, if I didn't get it wrong, I deduce that with web2py's pooling >> mechanism I can't overcome the "max_connections" postgresql limit. That is >> because, no matter the size of the pool, if the pool is full and the website >> is receiving a lot of requests, new connetions will be created, and >> eventually the database server will reach the "max_conectios" limit. > > > no, you got it wrong again. pool_size=5 will create AT MOST 5 connections . > if a 6th is needed, users will wait for a connection to be freed. > if your postgresql accept at most 50 connections, do the math. > Every db = DAL(, pool_size=5) lying around will create AT MOST 5 > connections, and that means you can host 10 apps. > If you need 50 apps, set pool_size=1 and let users wait, or set > max_connections in postgres to a higher value. > > -- > Resources: > - http://web2py.com > - http://web2py.com/book (Documentation) > - http://github.com/web2py/web2py (Source code) > - https://code.google.com/p/web2py/issues/list (Report Issues) > --- > You received this message because you are subscribed to a topic in the > Google Groups "web2py-users" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/web2py/5RTO_RqCsus/unsubscribe. > To unsubscribe from this group and all its topics, send an email to > web2py+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. -- Resources: - http://web2py.com - http://web2py.com/book (Documentation) - http://github.com/web2py/web2py (Source code) - https://code.google.com/p/web2py/issues/list (Report Issues) --- You received this message because you are subscribed to the Google Groups "web2py-users" group. To unsubscribe from this group and stop receiving emails from it, send an email to web2py+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
