Question

我正在使用HSQLDB v2.3.3和Hibernate v4.3.9.Final。我想验证FOR UPDATE是否在查询中有效。我的查询如下：

@NamedNativeQueries({
@NamedNativeQuery(name = "Building.lockBuildingByIdForUpdate", query = "SELECT b.* FROM building b WHERE b.id = :buildingId FOR UPDATE", resultClass = Building.class),
})

我的Java代码如下：

    public Object createNew( String buildingId ) {

      SimpleDateFormat format = new SimpleDateFormat( "yyyy-MM-dd hh:mm:ss,SSS" );

      System.out.println( format.format( System.currentTimeMillis() ) + ", Before acquiring lock..." + Thread.currentThread().getName() + ", buildingId=" + buildingId );
      buildingDao.lockBuildingsById(buildingId);
      System.out.println( format.format( System.currentTimeMillis() ) + " After acquiring lock..." + Thread.currentThread().getName() + ", buildingId=" + buildingId );

      //Some further Save data in the Database logic which I am omitting on purpose
}

我编写了一个测试用例，它产生如下两个线程：

executor.execute( new Runnable() {

        @Override
        public void run() {

            System.out.println( "First Thread Started..." + Thread.currentThread().getName() + ", buildingId=" + buildingId );
            Object job = getService().createNew( buildingId );
            System.out.println( "First Thread Ended..." + Thread.currentThread().getName() + ", buildingId=" + buildingId );
        }
    } );

    executor.execute( new Runnable() {

        @Override
        public void run() {

            System.out.println( "Second Thread Started..." + Thread.currentThread().getName() + ", buildingId=" + buildingId );
            Object job = getService().createNew( buildingId );
            System.out.println( "Second Thread Ended..." + Thread.currentThread().getName() + ", buildingId=" + buildingId );
        }
    } );

我的期望是，无论哪个线程获得锁定，都必须是唯一一个继续完成交易的人。然后只有第二个线程必须继续自己的执行。

但是，这不是我所看到的。我看到线程几乎同时获得了锁。我的输出如下：

First Thread Started...pool-7-thread-1, buildingId=bldg_id_1
Second Thread Started...pool-7-thread-2, buildingId=bldg_id_1
2017-11-29 03:49:34,527, Before acquiring lock...pool-7-thread-2, buildingId=bldg_id_1
2017-11-29 03:49:34,527, Before acquiring lock...pool-7-thread-1, buildingId=bldg_id_1
2017-11-29 03:49:34,594 After acquiring lock...pool-7-thread-1, buildingId=bldg_id_1
2017-11-29 03:49:34,594 Retrieving SomeObject pool-7-thread-1, buildingId=bldg_id_1
2017-11-29 03:49:34,598 After acquiring lock...pool-7-thread-2, buildingId=bldg_id_1
2017-11-29 03:49:34,598 Retrieving SomeObject pool-7-thread-2, buildingId=bldg_id_1
2017-11-29 03:49:34,674 Got SomeObject pool-7-thread-2, buildingId=bldg_id_1
2017-11-29 03:49:34,674 Got SomeObject pool-7-thread-1, buildingId=bldg_id_1
2017-11-29 03:49:34,711 Saved  newJob in DB pool-7-thread-2, buildingId=bldg_id_1
2017-11-29 03:49:34,711 Saved  newJob in DB pool-7-thread-1, buildingId=bldg_id_1
Second Thread Ended...pool-7-thread-2, buildingId=bldg_id_1
First Thread Ended...pool-7-thread-1, buildingId=bldg_id_1

因此输出清楚地表明没有应用锁定，并且两个线程都能够获得相同的锁定。

我的问题：HSQLDB v2.3.3是否支持FOR UPDATE？我在互联网[SELECT FOR UPDATE in hsqldb using hibernate上看到了它。根据经验不同。

HSQLDB是否支持FOR UPDATE？

0 个答案: