java - Why this error - Cannot get a connection, pool error Timeout waiting for idle object -

i having webapp on production, runs fine 7-8 days website down , logs reproduce error:

java.sql.sqlexception: cannot connection, pool error timeout waiting idle object

and operations database starts failing. have read across several other questions , blog not able find definite solution. using connection pool, , not sure problem is.

is because of code have written or pool configuration? providing code here 1 of method gets data database , pool configuration. please have , let me know if doing wrong.

public cartitem getcustomercartitem(int customerid, int productid, int productofcityid) {     connection con = connectionpool.getinstance().getconnection();     preparedstatement st = null;     resultset rs = null;     cartitem ci = null;      cityproduct cityproduct = productservice.getcityproduct(productid, productofcityid);     if (cityproduct == null) {         return null;     }      string query = "select ci.* customer_cart_item_mapping cim inner join cart_item ci on ci.id = cim.cartitemid "             + "cim.customerid = ? , ci.productofcityid = ?";      try {         st = con.preparecall(query);          st.setint(1, customerid);         st.setint(2, productofcityid);          rs = st.executequery();          if (rs.first()) {             ci = new cartitem();             ci.setid(rs.getint("id"));             ci.setcityproduct(cityproduct);             ci.setquantity(rs.getint("quantity"));             ci.setcreateddate(rs.getdate("createddate"));             ci.setupdateddate(rs.getdate("updateddate"));         }     } catch (sqlexception ex) {         logger lgr = logger.getlogger(cartitemdaoimpl.class.getname());         lgr.log(level.severe, ex.getmessage(), ex);      } {         dbutil.close(con, st, rs);     }      return ci; } 

below dbutil class used close connections:

public class dbutil {

public static void close(connection c, statement s, resultset r) {     try {         if (r != null) {             r.close();         }         if (s != null) {             s.close();         }         if (c != null) {             connectionpool.getinstance().freeconnection(c);         }      } catch (sqlexception ex) {         logger.getlogger(dbutil.class.getname()).log(level.severe, null, ex);     } } 

}

following connectionpool class

public class connectionpool { private static connectionpool pool=null; private static datasource datasource = null;  public synchronized static connectionpool getinstance(){     if (pool == null){         pool = new connectionpool();     }     return pool; }  private connectionpool(){     try{         initialcontext ic = new initialcontext();         datasource = (datasource) ic.lookup("java:/comp/env/jdbc/prod_db");     }     catch(namingexception e){         system.out.println(e);     } }  public connection getconnection(){     try{         return datasource.getconnection();     }     catch (sqlexception sqle){         system.err.println(sqle);         return null;     } }  public void freeconnection(connection c){     try{         c.close();     }     catch (sqlexception sqle){         system.err.println(sqle);     } } 

}

below connection pool configuration

<context antijarlocking="true" path="/">   <resource auth="container" connectionproperties="useencoding=true;" driverclassname="com.mysql.jdbc.driver" initialsize="2"         logabandoned="true" maxidle="40" maxtotal="70" maxwaitmillis="1000" minevictableidletimemillis="600000" minidle="2" name="jdbc/winni_prime_db"         password="password" removeabandoned="true" removeabandonedtimeout="90" testwhileidle="true" timebetweenevictionrunsmillis="90000"         type="javax.sql.datasource" url="jdbc:mysql://localhost:3306/prod_db"         username="sqladmin" validationquery="select 1"/> 

this problem has been persistent last several months. solution restart tomcat every night. please take @ code , give me expert opinion doing wrong. using mysql

you can potentially have lick here:

if (cityproduct == null) {     return null; } 

you got connection before code, can exit function without closing connection.