为什么我的DBUnit测试消耗这么多内存?

我有一个基于休眠的应用程序,它使用dbunit进行单元测试。我们有一个XML测试数据库,它在每个测试的setup()中加载了虚拟数据,并在拆卸()期间删除了这些数据。问题是我不能再在一个IDE中运行整个套件(在本例中是Intellij),因为在大约300次测试之后,堆内存将全部用完。测试的执行时间从大约0.3秒到30秒,直到JVM最终放弃并死亡。

当我通过Ant的JUnit任务运行测试套件时,这没有问题,也没有为单个类运行测试套件。但是,我喜欢在签入对代码库的大型重构更改之前在本地运行整个套件,而不是破坏CI服务器上的构建。

我运行的测试套件只有-xmx512m作为jvm的唯一参数,这与在CI服务器上运行任务时传递给Ant的量相同。我的hibernate-test.cfg.xml如下所示:

<hibernate-configuration>
  <session-factory>
    <!-- Database connection settings -->
    <property name="connection.driver_class">org.hsqldb.jdbcDriver</property>
    <property name="connection.url">jdbc:hsqldb:mem:mydatabase</property>
    <property name="connection.username">sa</property>
    <property name="connection.password"/>

    <!-- Other configuration properties -->
    <property name="connection.pool_size">1</property>
    <property name="jdbc.batch_size">20</property>
    <property name="connection.autocommit">true</property>
    <property name="dialect">org.hibernate.dialect.HSQLDialect</property>
    <property name="current_session_context_class">thread</property>
    <property name="cache.provider_class">org.hibernate.cache.HashtableCacheProvider</property>
    <property name="bytecode.use_reflection_optimizer">false</property>
    <property name="show_sql">true</property>
    <property name="hibernate.hbm2ddl.auto">create-drop</property>

    <!-- Mappings (omitted for brevity) -->
    <mapping resource="hbm/blah.hbm.xml"/>
  </session-factory>
</hibernate-configuration>

我们已经编写了一个类,所有测试类都从这个类扩展而来,它看起来像这样:

package com.mycompany.test;
// imports omitted for brevity

public abstract class DBTestCase extends TestCase {

  private final String XML_DATA_SET = "test/resources/mytestdata.xml";
  private Session _session;
  private Configuration _config;

  public DBTestCase(String name) {
    super(name);
  }

  @Override
  protected void setUp() throws Exception {
    super.setUp();
    _config = new Configuration().configure();
    SessionFactory sf = _config.buildSessionFactory();
    // This is a singleton which is used the DAO's to acquire a session.
    // The session must be manually set from the test's setup so that any
    // calls to the singleton return this session factory, otherwise NPE
    // will result, since the session factory is normally built during
    // webapp initialization.
    HibernateUtil.setSessionFactory(sf);
    _session = sf.openSession();
    _session.beginTransaction();

    IDataSet dataSet = new FlatXmlDataSet(new File(XML_DATA_SET));
    DatabaseOperation.CLEAN_INSERT.execute(getConnection(), dataSet);
  }

  protected void tearDown() throws Exception {
    super.tearDown();
    _session.close();
  }

  protected IDatabaseConnection getConnection() throws Exception {
    ConnectionProvider connProvider = ConnectionProviderFactory
      .newConnectionProvider(_config.getProperties());
    Connection jdbcConnection = connProvider.getConnection();
    DatabaseConnection dbConnection = new DatabaseConnection(jdbcConnection);
    DatabaseConfig dbConfig = dbConnection.getConfig();
    dbConfig.setProperty(DatabaseConfig.PROPERTY_DATATYPE_FACTORY, new HsqldbDataTypeFactory());
    return dbConnection;
  }
}

很明显这里发生了内存泄漏,但我不确定在哪里。我该怎么诊断呢?