Kevin thank you very much for your advice, they are helps me a lot. 2014-06-20 21:54 GMT+04:00 Kevin Grittner <kgrittn@xxxxxxxxx>: > Евгений Селявка <evg.selyavka@xxxxxxxxx> wrote: > >> Hi, Kevin >> I want to ask you about experience with java and dbcp pool, could >> you describe this case in detail. > > Well, the pooler I have the most experience with is one that I > designed and wrote under Java 1.0 for Wisconsin Courts. It > continued to work well for us until the time I left, about 16 years > later, with minimal adjustments to take advantage of newer > capabilities in later versions of Java as they came along. But > before I left they were looking at reworking their software stack > using packages from outside, and I reviewed various Java-based > poolers to see how well I thought they would work. IMO, dbcp was > the best of the lot that I reviewed. > >> I have one database and several app each of this app have own >> datasource, which is a dbcp pool object. Maybe it is good >> practice to use pgbouncer before dbcp data sources(but my opinion >> it is not good practice to have 2 pool before database), or i >> should calculate all dbcp datasources from all app with formula >> sum(maxActive)=max connection - 3. > > The goal is to try to limit the total number of active database > transactions to the number that the database can handle > efficiently, or as close as you can get to that. When you have > multiple pools in parallel, you need to add the maximum database > connections from all of them. I would try to avoid a second layer > of pooling, but if you can't limit the numbers and sizes of the > Java pools enough to prevent performance problems due to > concurrency, putting pgbouncer in front of the server would not be > crazy. > >> And what about another java pool realization, like HikariCP, do >> you try them? > > That is not one I reviewed. > >> This is my sample property file for dbcp: > > I don't remember all the settings and what they do, but the goal > would be to queue requests to start a transaction when a pool was > already at its maximum. My recollection is that this is what dbcp > does by default. Well, one thing to look at: I might try setting > initial and maximum pool sizes the same, to avoid a lot of > connection opening and closing during shifts in load. Logging > connections and disconnections will help you spot thrashing of that > sort. > > The best thing is to try incremental changes to the sizing of the > pool with production load with your actual application, and closely > monitor results. I know I was surprised by how much reducing the > pool size improved performance of our application and allowed it to > scale better with thousands of users. > > -- > Kevin Grittner > EDB: http://www.enterprisedb.com > The Enterprise PostgreSQL Company -- Best Regards, Seliavka Evgenii
