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POjava c3po statement for every query
 

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  1. POjava c3po statement for every query
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    <p>I am a beginner in JDBC and in my research i find best review on C3PO as i already tried BoneCP, only to find it doesn't close connections.</p> <p>I need a connection pool, maybe also a statement pool, for a multithreading soft real time software (trading system)</p> <p>This is an example of "SELECT":</p> <ol> <li>is it good?</li> <li>do i need to getConn() and then create statement and close both for every query?</li> <li><p>any general comments or suggestions?</p> <pre><code> Connection conn = null; ResultSet rs = null; Statement st = null; String query = null; try { query = " SELECT id " + " FROM " + DBTables.PandaSources; //rs = DB.ConnPool.invoke(conn, query, rs); st = DB.ConnPool.getSt(); rs = st.executeQuery(query); if (rs != null) { while (rs.next()) { ..... ...... } } } catch (Exception e) { e.printStackTrace(); Util.logException(e); } finally { if (rs != null) try { rs.close(); } catch (SQLException e) { e.printStackTrace(); Util.logException(e); } if (st != null) try { st.close(); } catch (SQLException e) { e.printStackTrace(); Util.logException(e); } if (conn != null) try { conn.close(); } catch (SQLException e) { e.printStackTrace(); Util.logException(e); } } query = null; st = null; rs = null; conn = null; } public static synchronized Statement getSt() throws SQLException { return getConn().createStatement(); } public static synchronized Connection getConn() throws SQLException { if (connectionPoolDatasource == null) { initPool(); } return connectionPoolDatasource.getConnection(); </code></pre> <p>}</p> <pre><code> public static synchronized void initPool() throws SQLException { DBLocation loc = null; try { loc = GTMain.DBConn.get(Util.DB_GURUSTRADE); // C3PO connectionPoolDatasource = new ComboPooledDataSource(); connectionPoolDatasource.setDriverClass(loc.driver); connectionPoolDatasource.setJdbcUrl(loc.url); connectionPoolDatasource.setUser(loc.user); connectionPoolDatasource.setPassword(loc.password); // properties connectionPoolDatasource.setAcquireIncrement(5); connectionPoolDatasource.setMaxIdleTime(3600); connectionPoolDatasource.setMaxIdleTimeExcessConnections(300); connectionPoolDatasource.setMaxPoolSize(100); connectionPoolDatasource.setMinPoolSize(20); connectionPoolDatasource.setNumHelperThreads(6); connectionPoolDatasource.setUnreturnedConnectionTimeout(3600); } catch (Exception e) { e.printStackTrace(); } </code></pre> <p>}</p></li> </ol>
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    1. PTQuestion
    1. USuser502967
    1. USuser502967
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    1. COWhether pooling or not, it is always a safe idea to `close()` the resources like `Connection`, and `Statement`. In case of pooling, `close()` call on the proxy returned to you will return the resource like connection back to the pool for reuse.
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      1. POjava c3po statement for every query
      1. USBimalesh Jha
    2. COYou don't show, and I bet I won't like, what's going on in DB.ConnPool.getSt(). From what Connection is the Statement being acquired? What's its lifecycle? Is it close()ed, ie returned to the pool, when it is not in use? In general, you should just grab a Connection from the pool on each use, do some unit of work, and the close the resources, including the Connection. (A unit of work may be more than one Statement execution! Any set of operations continuously sequential in time can be a unit of work that shares a Connection.)
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      1. POjava c3po statement for every query
      1. USSteve Waldman
    3. CO've added all missing functiins :) thanks for your help
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      1. POjava c3po statement for every query
      1. USuser502967
 

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