Connection not released back to the tomcat jdbc pool

Question

I have a grails2 based application which is using tomcat jdbc pool, recently I have been getting into problem where all the connections in the pool get used up and I start getting:-

org.springframework.transaction.CannotCreateTransactionException: Could not open Hibernate Session for transaction; nested exception is org.apache.tomcat.jdbc.pool.PoolExhaustedException: [http-nio-8443-exec-38] Timeout: Pool empty. Unable to fetch a connection in 10 seconds, none available[size:100; busy:100; idle:0; lastwait:10000].; nested exception is org.springframework.transaction.CannotCreateTransactionException: Could not open Hibernate Session for transaction; nested exception is org.apache.tomcat.jdbc.pool.PoolExhaustedException: [http-nio-8443-exec-38] Timeout: Pool empty. Unable to fetch a connection in 10 seconds, none available[size:100; busy:100; idle:0; lastwait:10000].

I have a few query that requires heavy join and some stored proc that executes for about 2 - 3 minutes, for it i am manually get the connection from the datasource bean :-

currentConnection = dataSource.connection
sqlInstance = new Sql(currentConnection)
sqlInstance.execute(query)
sqlInstance.close()

I've logged the total active connection in stdout and i see that the no. of active connection keeps on rising and rising and it never drops, it then gets to 100 which is the total active connection allowed and then i start getting issue of poolexhaustauion, can anyone give me an idea, what i might be missing or where the connection might be leaking. here is my connection detail :-

dataSource {
    pooled = true
    driverClassName = "com.mysql.jdbc.Driver"
    url="jdbc:mysql://something:3306/something?zeroDateTimeBehavior=convertToNull&autoReconnect=true&relaxAutoCommit=true"
    username="#####"
    password='#$#$$$$$$$'
    dbCreate = "update" 
    properties {
        initialSize=5
        maxActive=100
        minIdle=5
        maxIdle=25
        maxWait = 10000
        maxAge = 10 * 60000
        timeBetweenEvictionRunsMillis=5000
        minEvictableIdleTimeMillis=60000
        validationQuery="SELECT 1"
        validationInterval=15000
        testWhileIdle=true
        testOnBorrow=true
        testOnReturn=true
        removeAbandoned=true
        removeAbandonedTimeout=400
        logAbandoned=true
        jdbcInterceptors = "ConnectionState"
        defaultTransactionIsolation = java.sql.Connection.TRANSACTION_READ_COMMITTED
    }
}