All connections are active in Tomcat datasource pool with Spring - spring

Question

My Spring Boot application uses JDBCTemplate to send SQL queries to a PostgreSQL Database. It seems that each time a connection is got from the pool by the template, the connection is never released. The number of active connections (datasource.primary.active) is always increasing.
In the logs, after SQL Query using JDBCTemplate, I can see :
DEBUG o.s.j.d.DataSourceUtils - Returning JDBC Connection to DataSource
But the count of idle connection stay with the same value and the count of active connections is not decreasing. When the maximum value is reached, it becomes impossible to retrieve a connection to execute a query.
So, I think there is no return of the connection to the datasource pool, any idea please ?
Here is the datasource configuration got with Actuator :
"dataSource": {
"prefix": "spring.datasource.tomcat",
"properties": {
"connectionProperties": null,
"propagateInterruptState": false,
"validator": null,
"useDisposableConnectionFacade": true,
"defaultCatalog": null,
"validationInterval": 3000,
"jmxEnabled": true,
"ignoreExceptionOnPreLoad": false,
"logAbandoned": false,
"commitOnReturn": false,
"password": "******",
"maxIdle": 100,
"testWhileIdle": false,
"removeAbandoned": false,
"poolProperties": {
"dbProperties": {
"user": "postgres",
"password": "******"
},
"url": "jdbc:postgresql://localhost:5432/tvir",
"driverClassName": "org.postgresql.Driver",
"defaultAutoCommit": null,
"defaultReadOnly": null,
"defaultTransactionIsolation": -1,
"defaultCatalog": null,
"connectionProperties": null,
"initialSize": 10,
"maxActive": 100,
"maxIdle": 100,
"minIdle": 10,
"maxWait": 30000,
"validationQuery": "SELECT 1",
"validationQueryTimeout": -1,
"validatorClassName": null,
"validator": null,
"testOnBorrow": true,
"testOnReturn": false,
"testWhileIdle": false,
"timeBetweenEvictionRunsMillis": 5000,
"numTestsPerEvictionRun": 0,
"minEvictableIdleTimeMillis": 60000,
"accessToUnderlyingConnectionAllowed": true,
"removeAbandoned": false,
"removeAbandonedTimeout": 60,
"logAbandoned": false,
"name": "Tomcat Connection Pool[1-574817798]",
"password": "******",
"username": "postgres",
"validationInterval": 3000,
"jmxEnabled": true,
"initSQL": null,
"testOnConnect": false,
"jdbcInterceptors": null,
"fairQueue": true,
"useEquals": true,
"abandonWhenPercentageFull": 0,
"maxAge": 0,
"useLock": false,
"suspectTimeout": 0,
"dataSource": null,
"dataSourceJNDI": null,
"alternateUsernameAllowed": false,
"commitOnReturn": false,
"rollbackOnReturn": false,
"useDisposableConnectionFacade": true,
"logValidationErrors": false,
"propagateInterruptState": false,
"ignoreExceptionOnPreLoad": false,
"useStatementFacade": true
},
And the code used to query the db :
JdbcTemplate jdbcTemplate = appCtx.getBean(JdbcTemplate.class);
ResultSet columns = jdbcTemplate.getDataSource().getConnection().getMetaData().getColumns(null, null, source.getTable().toLowerCase(), null);
String selectList = "";
while (columns.next())
{
String colName = columns.getString("COLUMN_NAME");
String colType = columns.getString("DATA_TYPE");
if(!selectList.equals("")) {
selectList += ", ";
}
if((""+java.sql.Types.INTEGER).equalsIgnoreCase(colType) ||
(""+java.sql.Types.DOUBLE).equalsIgnoreCase(colType) ||
(""+java.sql.Types.BIGINT).equalsIgnoreCase(colType) ||
(""+java.sql.Types.FLOAT).equalsIgnoreCase(colType) ) {
selectList += "SUM(" + colName + ")";
} else {
selectList += "MAX(" + colName + ")";
}
selectList += " AS "+colName;
}
String sql = "SELECT "+selectList+" FROM "+source.getTable()+" "+
"WHERE "+source.getDateColumn()+" >= ? "+
"AND "+source.getDateColumn()+" <= ? ";
List<Map<String, Object>> results = jdbcTemplate.queryForList(sql, Date.valueOf(startDate), Date.valueOf(endDate));

Answer 1

Spring boot let you configure how you want your datasource to behave.
You will find a full list on the official doc.
check the following properties for your case :
spring.datasource.maxActive
spring.datasource.maxIdle
Depending on what connection pool you are using you can also tune it using spring boot properties (everything is in the doc) .