Cannot get a connection, pool error Timeout waiting for idle object

Question

my connection pool setting is
  maxActive="3" minIdle="2"                maxWait="10000"              removeAbandoed="true" logAbandoned="true"         removeAbandonedTimeout="30"         autoreconnection="true" 
we have 7 people hitting the group of search functions ,
about 3 minutes I get
I got error like
org.apache.tomcat.dbcp.dbcp.SQLNestedException: Cannot get a connection, pool error Timeout waiting for idle object         at org.apache.tomcat.dbcp.dbcp.PoolingDataSource.getConnection(PoolingDataSource.java:104)         at org.apache.tomcat.dbcp.dbcp.BasicDataSource.getConnection(BasicDataSource.java:880)         at Deferment.showResult.checStudent(showResult.java:135)         at Deferment.showResult.doPost(showResult.java:99)         at javax.servlet.http.HttpServlet.service(HttpServlet.java:710)         at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)         at org.apache.catalina.servlets.InvokerServlet.serveRequest(InvokerServlet.java:402)         at org.apache.catalina.servlets.InvokerServlet.doPost(InvokerServlet.java:170)         at javax.servlet.http.HttpServlet.service(HttpServlet.java:710)         at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
I just wonder
1) Cannot get a connection, pool error Timeout waiting for idle object-> cause by connection pool leaking or other problem.
2) Setting the maxactive to -1 ( suggestion from Google) , if I set my connection to ulimit , waht should I put on minIdle="2"
3) How can I test my connection pool have problem or not ? is
SHOW PROCESSLIST; tolding me someinformation? I use Mysql
Thank you!

Answer 1

I try something like ps2 = conn.prepareStatement(target);
            ps2.setString(1, UNumber); // set input parameter
            rs = ps2.executeQuery();
            sendMail = 0;//how many rows we can find.
            while (rs.next()) {
                sendMail++;
            ps2.close();
            rs.close();
            conn.close();
  if ((count1 == 0) || (count2 == 0)) {
                conn.rollback();
            } else {
                conn.commit();
                conn.setAutoCommit(true);
            ps.close();
            calstat2.close();
            conn.close();
calstat = (CallableStatement) conn.prepareCall("{call findStudent}");
            calstat.executeQuery();
            calstat.close();
            conn.close();is that enought? what else I should do to make sure I did close all the connection, after I use it ?
thank you