Modeshape 5 open database connections

[mohideen]

I have noticed that the database connection threads in the postgres server are never closed. They are in an idle state when there is no active usage. We use Modeshape 5.1.0.Final (Fcrepo 4.7.0) and postgres 9.5.

Here is our persistence configuration:

     persistence": {

            "type" : "db",

            "connectionUrl": "jdbc:postgresql://server:5432/db",

            "driver" : "org.postgresql.Driver",

            "username" : "username",

            "password" : "password",

            "poolSize" : 20

        }

The number of open threads is based on the poolSize configuration. When we had 50 as the poolSize we had 50 idle postgres threads and when we lowered it to 20, the idle threads came down to 20. I just want to check if this is how the database connection is supposed to work or if the connections are supposed to be closed after a period of no activity. Also, what would be the recommended value for the poolSize paramater?

Thanks in advance!

[hchiorean]

When ran outside of Wildfly, the DB connections used by ModeShape are provided by HikariCP (https://brettwooldridge.github.io/HikariCP/).

So to answer your question, afaik this is the way Hikari behaves: it uses a maximum number of idle connections (based on the poolSize param) and if any of them are unused, it *should* discard them based on the idleTimeout setting (currently this is not configurable via ModeShape and is set to 1 minute).

You can see the code here: modeshape/DataSourceManager.java at master · ModeShape/modeshape · GitHub

[mohideen]

Thanks for your quick reply! I will investigate the HikariCP behavior.

[illia.khokholkov]

Where did your investigation land? Thank you.

[mohideen]

See: [MODE-2674] Modeshape 5 open database connections with HikariCP - JBoss Issue Tracker

[mohideen]

Resolved in Modeshape 5.4 with changes from [MODE-2674] Add the ability to configure the minIdle property for HikariCP - JBoss Issue Tracker