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org.apache.tomcat.dbcp.dbcp.SQLNestedException: Cannot get a connection, pool error Timeout waiting for idle object

由 别等时光非礼了梦想. 提交于 2019-12-09 01:15:31
baba.kabira

what are you connection pool settings can you post whats in DBController? Tip: db.terminate() should be in finally{} block, may be you are lossing connections on exceptions.

Update: Posting some of the modifications that might help you, but DO CLEAN UP THE CODE for maintenance sake. Look for comments where changes have been made.

public class DBController {
private DataSource ds;
private Connection con;// NEW CHANGE

public void setUp() throws NamingException{
    //connect to database
    Context ctx = new InitialContext();
    ds = (DataSource)ctx.lookup("java:comp/env/jdbc/it2299");
    con = ds.getConnection(); // NEW CHANGE
}

public ResultSet readRequest(String dbQuery){
    ResultSet rs=null;
    try{
        //REMOVED CODE FROM HERE
        Statement stmt = con.createStatement();
        rs = stmt.executeQuery(dbQuery);
    }
    catch(Exception e){e.printStackTrace();}
    return rs;
}

public int updateRequest(String dbQuery){
    int count=0;
    try{
        //REMOVED CODE FROM HERE
        Statement stmt = con.createStatement();
        count=stmt.executeUpdate(dbQuery);
    }
    catch(Exception e){e.printStackTrace();}
    return count;
}

public void terminate(){
    try {con.close();}
    catch(Exception e){e.printStackTrace();}
}
}

Code cannot be improved beyond this by me, but I suggest have a look at some of the best practices over net and as suggested by @BalusC. Remember: To close the connection object when done.

BalusC

As you hinted yourself, your code is horrible. You need to ensure that all JDBC resources are acquired and closed in the shortest possibe scope in a try-finally block. Rewrite your code so that it follows the following standard JDBC idiom:

public List<Entity> list() throws SQLException {
    Connection connection = null;
    PreparedStatement statement = null;
    ResultSet resultSet = null;
    List<Entity> entities = new ArrayList<Entity>();

    try {
        connection = Database.getConnection();
        statement = connection.prepareStatement("SELECT id, foo, bar FROM entity");
        resultSet = statement.executeQuery();

        while (resultSet.next()) {
            Entity entity = new Entity();
            entity.setId(resultSet.getLong("id"));
            entity.setFoo(resultSet.getString("foo"));
            entity.setBar(resultSet.getString("bar"));
            entities.add(entity);
        }
    } finally {
        if (resultSet != null) try { resultSet.close(); } catch (SQLException ignore) {}
        if (statement != null) try { statement.close(); } catch (SQLException ignore) {}
        if (connection != null) try { connection.close(); } catch (SQLException ignore) {}
    }

    return entities;
}

See also:

标签
exception
java-ee
jsf-2
tomcat7
mysql-workbench
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