Question

此代码中的内存泄漏在哪里？大量使用内存会导致此函数执行数百万次，导致240万次执行后内存不足。

public static void saveCall(Call call) {
        conn = getInstance();

        if (conn != null) {
            try {
                calendar.setTime(call.getDate());
                String sql = "INSERT INTO Calls(id, datetime, duration, customer_phone_id, partner_phone_id) "
                        + "VALUES(null, ?, ?, ?, ?)";
                PreparedStatement preparedStatement = conn
                        .prepareStatement(sql);
                preparedStatement.setString(1, dateFormat.format(calendar.getTime()));
                preparedStatement.setLong(2, call.getDuration());
                preparedStatement.setLong(3, call.getPhone().getPhoneNumber());
                preparedStatement.setLong(4, call.getPhonePartner()
                        .getPhoneNumber());

                preparedStatement.executeUpdate();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }

Answer 1

如果您的程序使用大量内存，则可能没有泄漏但只有垃圾收集器问题。 IE浏览器，你的垃圾来得太晚，无法释放一些空间来创建新对象。

从这里开始，您可能希望在运行查询时对代码进行概要分析（随任何jdk提供的visualvm或jconsole）。你将看到你的内存空间是如何填充的（垃圾行为和对象大小）。

然后，如果需要，您将需要配置您的jvm垃圾收集这里有大量文档：http://www.oracle.com/technetwork/java/javase/gc-tuning-6-140523.html 如果您共享内存配置文件，我们可能会帮助您配置它。

编辑：内存泄漏，我错了; - ）

Answer 2

@Pascal Bayer：你应该在SQL操作后关闭你的连接。带close（）的修改后的代码看起来就像下面那样。

public static void saveCall(Call call) {
        conn = getInstance();

        if (conn != null) {
            try {
                calendar.setTime(call.getDate());
                String sql = "INSERT INTO Calls(id, datetime, duration, customer_phone_id, partner_phone_id) "
                        + "VALUES(null, ?, ?, ?, ?)";
                PreparedStatement preparedStatement = conn
                        .prepareStatement(sql);
                preparedStatement.setString(1, dateFormat.format(calendar.getTime()));
                preparedStatement.setLong(2, call.getDuration());
                preparedStatement.setLong(3, call.getPhone().getPhoneNumber());
                preparedStatement.setLong(4, call.getPhonePartner()
                        .getPhoneNumber());

                preparedStatement.executeUpdate();
            } catch (SQLException e) {
                e.printStackTrace();
            } finally {
              // good practice of closing connections as soon as 
              // the SQL operations are       completed
              if(!conn.isClosed())
                conn.close();
            }
        }
}

干杯，马杜。

Answer 3

我的两分钱

JDBC is tricky

在这种情况下，应关闭PreparedStatement以避免资源泄漏。

public static void saveCall(Call call) {
    conn = getInstance();

    if (conn != null) {
        calendar.setTime(call.getDate());
        String sql = "INSERT INTO Calls(id, datetime, duration, customer_phone_id, partner_phone_id) "
                    + "VALUES(null, ?, ?, ?, ?)";

        PreparedStatement preparedStatement = null;            
        try {               
            conn.prepareStatement(sql);
            preparedStatement.setString(1, dateFormat.format(calendar.getTime()));
            preparedStatement.setLong(2, call.getDuration());
            preparedStatement.setLong(3, call.getPhone().getPhoneNumber());
            preparedStatement.setLong(4, call.getPhonePartner()
                    .getPhoneNumber());

            preparedStatement.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            if (preparedStatement != null) {
                preparedStatement.close();
            }
        }
    }
}

这是Java 7解决方案：

public static void saveCall(Call call) {
    conn = getInstance();

    if (conn != null) {
        calendar.setTime(call.getDate());
        String sql = "INSERT INTO Calls(id, datetime, duration, customer_phone_id, partner_phone_id) "
                    + "VALUES(null, ?, ?, ?, ?)";

        try (PreparedStatement preparedStatement = conn.prepareStatement(sql)) {                
            preparedStatement.setString(1, dateFormat.format(calendar.getTime()));
            preparedStatement.setLong(2, call.getDuration());
            preparedStatement.setLong(3, call.getPhone().getPhoneNumber());
            preparedStatement.setLong(4, call.getPhonePartner()
                    .getPhoneNumber());

            preparedStatement.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

Java JDBC：MySQL写出内存不足

3 个答案: