Oracle Hibernate查询暂停，因为会话在未连接的情况下打开和关闭

我们有一个Grails应用程序，它使用Hibernate查询Oracle数据库

一个相对简单的条件查询，在最坏的情况下，直接通过SQL Developer之类的工具对数据库运行时需要二十分之一秒的时间，而完成查询则需要几分之一秒到30秒的时间

在将

logSql

设置为

true

并确认生成的SQL是可执行的（解释约100的计划成本和10-30毫秒的执行时间）之后，我们通过将Hibernate的日志记录级别设置为

TRACE

，进一步了解了Hibernate的用途

以下是我们在stdout中看到的内容：

******************** START HIBERNATE QUERY TRACE *****************
start time (millis): 1400772671767
2014-05-22 11:31:11,767 [http-bio-8080-exec-5] DEBUG transaction.JDBCTransaction  - begin
2014-05-22 11:31:11,767 [http-bio-8080-exec-5] DEBUG transaction.JDBCTransaction  - current autocommit status: true
2014-05-22 11:31:11,767 [http-bio-8080-exec-5] DEBUG transaction.JDBCTransaction  - disabling autocommit
2014-05-22 11:31:11,767 [http-bio-8080-exec-5] TRACE jdbc.JDBCContext  - after transaction begin
2014-05-22 11:31:11,770 [http-bio-8080-exec-5] TRACE loader.Loader  - querySpaces is [REDACTED]
2014-05-22 11:31:11,770 [http-bio-8080-exec-5] TRACE loader.Loader  - transformer=org.hibernate.transform.RootEntityResultTransformer returnTypes=[ REDACTED ] returnClasses=[ class REDACTED ]
2014-05-22 11:31:11,770 [http-bio-8080-exec-5] DEBUG jdbc.AbstractBatcher  - about to open PreparedStatement (open PreparedStatements: 0, globally: 0)
2014-05-22 11:31:11,771 [http-bio-8080-exec-5] DEBUG hibernate.SQL  - select REDACTED
2014-05-22 11:31:11,771 [http-bio-8080-exec-5] TRACE jdbc.AbstractBatcher  - preparing statement
2014-05-22 11:31:11,771 [http-bio-8080-exec-5] TRACE sql.BasicBinder  - binding parameter [1] as REDACTED
2014-05-22 11:31:11,771 [http-bio-8080-exec-5] TRACE sql.BasicBinder  - binding parameter [2] as REDACTED
2014-05-22 11:31:11,772 [http-bio-8080-exec-5] TRACE sql.BasicBinder  - binding parameter [3] as REDACTED
2014-05-22 11:31:11,772 [http-bio-8080-exec-5] TRACE loader.Loader  - Bound [4] parameters total
2014-05-22 11:31:12,323 [http-bio-8080-exec-10] DEBUG impl.SessionImpl  - opened session at timestamp: 5737564865835008
2014-05-22 11:31:12,324 [http-bio-8080-exec-10] TRACE impl.SessionImpl  - closing session
2014-05-22 11:31:12,324 [http-bio-8080-exec-10] TRACE jdbc.ConnectionManager  - connection already null in cleanup : no action
2014-05-22 11:31:12,324 [http-bio-8080-exec-10] DEBUG impl.SessionImpl  - opened session at timestamp: 5737564865839104
2014-05-22 11:31:12,324 [http-bio-8080-exec-10] TRACE impl.SessionImpl  - closing session
2014-05-22 11:31:12,324 [http-bio-8080-exec-10] TRACE jdbc.ConnectionManager  - connection already null in cleanup : no action
2014-05-22 11:31:14,331 [http-bio-8080-exec-10] DEBUG impl.SessionImpl  - opened session at timestamp: 5737564874059776
2014-05-22 11:31:14,331 [http-bio-8080-exec-10] TRACE impl.SessionImpl  - closing session
2014-05-22 11:31:14,331 [http-bio-8080-exec-10] TRACE jdbc.ConnectionManager  - connection already null in cleanup : no action
2014-05-22 11:31:14,331 [http-bio-8080-exec-10] DEBUG impl.SessionImpl  - opened session at timestamp: 5737564874059777
2014-05-22 11:31:14,331 [http-bio-8080-exec-10] TRACE impl.SessionImpl  - closing session
2014-05-22 11:31:14,332 [http-bio-8080-exec-10] TRACE jdbc.ConnectionManager  - connection already null in cleanup : no action
2014-05-22 11:31:16,339 [http-bio-8080-exec-10] DEBUG impl.SessionImpl  - opened session at timestamp: 5737564882284544
2014-05-22 11:31:16,339 [http-bio-8080-exec-10] TRACE impl.SessionImpl  - closing session
2014-05-22 11:31:16,339 [http-bio-8080-exec-10] TRACE jdbc.ConnectionManager  - connection already null in cleanup : no action
2014-05-22 11:31:16,339 [http-bio-8080-exec-10] DEBUG impl.SessionImpl  - opened session at timestamp: 5737564882284545
2014-05-22 11:31:16,340 [http-bio-8080-exec-10] TRACE impl.SessionImpl  - closing session
2014-05-22 11:31:16,340 [http-bio-8080-exec-10] TRACE jdbc.ConnectionManager  - connection already null in cleanup : no action
2014-05-22 11:31:18,348 [http-bio-8080-exec-10] DEBUG impl.SessionImpl  - opened session at timestamp: 5737564890513408
2014-05-22 11:31:18,348 [http-bio-8080-exec-10] TRACE impl.SessionImpl  - closing session
2014-05-22 11:31:18,348 [http-bio-8080-exec-10] TRACE jdbc.ConnectionManager  - connection already null in cleanup : no action
2014-05-22 11:31:18,348 [http-bio-8080-exec-10] DEBUG impl.SessionImpl  - opened session at timestamp: 5737564890513409
2014-05-22 11:31:18,349 [http-bio-8080-exec-10] TRACE impl.SessionImpl  - closing session
2014-05-22 11:31:18,349 [http-bio-8080-exec-10] TRACE jdbc.ConnectionManager  - connection already null in cleanup : no action
2014-05-22 11:31:20,356 [http-bio-8080-exec-10] DEBUG impl.SessionImpl  - opened session at timestamp: 5737564898738176
2014-05-22 11:31:20,356 [http-bio-8080-exec-10] TRACE impl.SessionImpl  - closing session
2014-05-22 11:31:20,356 [http-bio-8080-exec-10] TRACE jdbc.ConnectionManager  - connection already null in cleanup : no action
2014-05-22 11:31:20,356 [http-bio-8080-exec-10] DEBUG impl.SessionImpl  - opened session at timestamp: 5737564898738177
2014-05-22 11:31:20,357 [http-bio-8080-exec-10] TRACE impl.SessionImpl  - closing session
2014-05-22 11:31:20,357 [http-bio-8080-exec-10] TRACE jdbc.ConnectionManager  - connection already null in cleanup : no action
2014-05-22 11:31:22,364 [http-bio-8080-exec-10] DEBUG impl.SessionImpl  - opened session at timestamp: 5737564906958848
2014-05-22 11:31:22,364 [http-bio-8080-exec-10] TRACE impl.SessionImpl  - closing session
2014-05-22 11:31:22,364 [http-bio-8080-exec-10] TRACE jdbc.ConnectionManager  - connection already null in cleanup : no action
2014-05-22 11:31:22,364 [http-bio-8080-exec-10] DEBUG impl.SessionImpl  - opened session at timestamp: 5737564906962944
2014-05-22 11:31:22,364 [http-bio-8080-exec-10] TRACE impl.SessionImpl  - closing session
2014-05-22 11:31:22,364 [http-bio-8080-exec-10] TRACE jdbc.ConnectionManager  - connection already null in cleanup : no action
2014-05-22 11:31:24,373 [http-bio-8080-exec-10] DEBUG impl.SessionImpl  - opened session at timestamp: 5737564915191808
2014-05-22 11:31:24,373 [http-bio-8080-exec-10] TRACE impl.SessionImpl  - closing session
2014-05-22 11:31:24,373 [http-bio-8080-exec-10] TRACE jdbc.ConnectionManager  - connection already null in cleanup : no action
2014-05-22 11:31:24,373 [http-bio-8080-exec-10] DEBUG impl.SessionImpl  - opened session at timestamp: 5737564915191809
2014-05-22 11:31:24,374 [http-bio-8080-exec-10] TRACE impl.SessionImpl  - closing session
2014-05-22 11:31:24,374 [http-bio-8080-exec-10] TRACE jdbc.ConnectionManager  - connection already null in cleanup : no action
2014-05-22 11:31:26,379 [http-bio-8080-exec-10] DEBUG impl.SessionImpl  - opened session at timestamp: 5737564923408384
2014-05-22 11:31:26,379 [http-bio-8080-exec-10] TRACE impl.SessionImpl  - closing session
2014-05-22 11:31:26,379 [http-bio-8080-exec-10] TRACE jdbc.ConnectionManager  - connection already null in cleanup : no action
2014-05-22 11:31:26,379 [http-bio-8080-exec-10] DEBUG impl.SessionImpl  - opened session at timestamp: 5737564923408385
2014-05-22 11:31:26,379 [http-bio-8080-exec-10] TRACE impl.SessionImpl  - closing session
2014-05-22 11:31:26,379 [http-bio-8080-exec-10] TRACE jdbc.ConnectionManager  - connection already null in cleanup : no action
2014-05-22 11:31:28,387 [http-bio-8080-exec-10] DEBUG impl.SessionImpl  - opened session at timestamp: 5737564931633152
2014-05-22 11:31:28,387 [http-bio-8080-exec-10] TRACE impl.SessionImpl  - closing session
2014-05-22 11:31:28,387 [http-bio-8080-exec-10] TRACE jdbc.ConnectionManager  - connection already null in cleanup : no action
2014-05-22 11:31:28,387 [http-bio-8080-exec-10] DEBUG impl.SessionImpl  - opened session at timestamp: 5737564931633153
2014-05-22 11:31:28,387 [http-bio-8080-exec-10] TRACE impl.SessionImpl  - closing session
2014-05-22 11:31:28,388 [http-bio-8080-exec-10] TRACE jdbc.ConnectionManager  - connection already null in cleanup : no action
2014-05-22 11:31:30,395 [http-bio-8080-exec-10] DEBUG impl.SessionImpl  - opened session at timestamp: 5737564939857920
2014-05-22 11:31:30,396 [http-bio-8080-exec-10] TRACE impl.SessionImpl  - closing session
2014-05-22 11:31:30,396 [http-bio-8080-exec-10] TRACE jdbc.ConnectionManager  - connection already null in cleanup : no action
2014-05-22 11:31:30,396 [http-bio-8080-exec-10] DEBUG impl.SessionImpl  - opened session at timestamp: 5737564939862016
2014-05-22 11:31:30,396 [http-bio-8080-exec-10] TRACE impl.SessionImpl  - closing session
2014-05-22 11:31:30,396 [http-bio-8080-exec-10] TRACE jdbc.ConnectionManager  - connection already null in cleanup : no action
2014-05-22 11:31:32,403 [http-bio-8080-exec-10] DEBUG impl.SessionImpl  - opened session at timestamp: 5737564948082688
2014-05-22 11:31:32,404 [http-bio-8080-exec-10] TRACE impl.SessionImpl  - closing session
2014-05-22 11:31:32,404 [http-bio-8080-exec-10] TRACE jdbc.ConnectionManager  - connection already null in cleanup : no action
2014-05-22 11:31:32,404 [http-bio-8080-exec-10] DEBUG impl.SessionImpl  - opened session at timestamp: 5737564948086784
2014-05-22 11:31:32,404 [http-bio-8080-exec-10] TRACE impl.SessionImpl  - closing session
2014-05-22 11:31:32,404 [http-bio-8080-exec-10] TRACE jdbc.ConnectionManager  - connection already null in cleanup : no action
2014-05-22 11:31:34,408 [http-bio-8080-exec-10] DEBUG impl.SessionImpl  - opened session at timestamp: 5737564956295168
2014-05-22 11:31:34,409 [http-bio-8080-exec-10] TRACE impl.SessionImpl  - closing session
2014-05-22 11:31:34,409 [http-bio-8080-exec-10] TRACE jdbc.ConnectionManager  - connection already null in cleanup : no action
2014-05-22 11:31:34,409 [http-bio-8080-exec-10] DEBUG impl.SessionImpl  - opened session at timestamp: 5737564956299264
2014-05-22 11:31:34,409 [http-bio-8080-exec-10] TRACE impl.SessionImpl  - closing session
2014-05-22 11:31:34,409 [http-bio-8080-exec-10] TRACE jdbc.ConnectionManager  - connection already null in cleanup : no action
2014-05-22 11:31:36,416 [http-bio-8080-exec-10] DEBUG impl.SessionImpl  - opened session at timestamp: 5737564964519936
2014-05-22 11:31:36,416 [http-bio-8080-exec-10] TRACE impl.SessionImpl  - closing session
2014-05-22 11:31:36,416 [http-bio-8080-exec-10] TRACE jdbc.ConnectionManager  - connection already null in cleanup : no action
2014-05-22 11:31:36,416 [http-bio-8080-exec-10] DEBUG impl.SessionImpl  - opened session at timestamp: 5737564964519937
2014-05-22 11:31:36,416 [http-bio-8080-exec-10] TRACE impl.SessionImpl  - closing session
2014-05-22 11:31:36,417 [http-bio-8080-exec-10] TRACE jdbc.ConnectionManager  - connection already null in cleanup : no action
2014-05-22 11:31:38,421 [http-bio-8080-exec-10] DEBUG impl.SessionImpl  - opened session at timestamp: 5737564972732416
2014-05-22 11:31:38,422 [http-bio-8080-exec-10] TRACE impl.SessionImpl  - closing session
2014-05-22 11:31:38,422 [http-bio-8080-exec-10] TRACE jdbc.ConnectionManager  - connection already null in cleanup : no action
2014-05-22 11:31:38,422 [http-bio-8080-exec-10] DEBUG impl.SessionImpl  - opened session at timestamp: 5737564972736512
2014-05-22 11:31:38,422 [http-bio-8080-exec-10] TRACE impl.SessionImpl  - closing session
2014-05-22 11:31:38,422 [http-bio-8080-exec-10] TRACE jdbc.ConnectionManager  - connection already null in cleanup : no action
2014-05-22 11:31:40,428 [http-bio-8080-exec-10] DEBUG impl.SessionImpl  - opened session at timestamp: 5737564980953088
2014-05-22 11:31:40,429 [http-bio-8080-exec-10] TRACE impl.SessionImpl  - closing session
2014-05-22 11:31:40,429 [http-bio-8080-exec-10] TRACE jdbc.ConnectionManager  - connection already null in cleanup : no action
2014-05-22 11:31:40,429 [http-bio-8080-exec-10] DEBUG impl.SessionImpl  - opened session at timestamp: 5737564980957184
2014-05-22 11:31:40,429 [http-bio-8080-exec-10] TRACE impl.SessionImpl  - closing session
2014-05-22 11:31:40,429 [http-bio-8080-exec-10] TRACE jdbc.ConnectionManager  - connection already null in cleanup : no action
2014-05-22 11:31:42,436 [http-bio-8080-exec-10] DEBUG impl.SessionImpl  - opened session at timestamp: 5737564989177856
2014-05-22 11:31:42,437 [http-bio-8080-exec-10] TRACE impl.SessionImpl  - closing session
2014-05-22 11:31:42,437 [http-bio-8080-exec-10] TRACE jdbc.ConnectionManager  - connection already null in cleanup : no action
2014-05-22 11:31:42,437 [http-bio-8080-exec-10] DEBUG impl.SessionImpl  - opened session at timestamp: 5737564989181952
2014-05-22 11:31:42,437 [http-bio-8080-exec-10] TRACE impl.SessionImpl  - closing session
2014-05-22 11:31:42,437 [http-bio-8080-exec-10] TRACE jdbc.ConnectionManager  - connection already null in cleanup : no action
2014-05-22 11:31:44,441 [http-bio-8080-exec-10] DEBUG impl.SessionImpl  - opened session at timestamp: 5737564997390336
2014-05-22 11:31:44,442 [http-bio-8080-exec-10] TRACE impl.SessionImpl  - closing session
2014-05-22 11:31:44,442 [http-bio-8080-exec-10] TRACE jdbc.ConnectionManager  - connection already null in cleanup : no action
2014-05-22 11:31:44,442 [http-bio-8080-exec-10] DEBUG impl.SessionImpl  - opened session at timestamp: 5737564997394432
2014-05-22 11:31:44,442 [http-bio-8080-exec-10] TRACE impl.SessionImpl  - closing session
2014-05-22 11:31:44,442 [http-bio-8080-exec-10] TRACE jdbc.ConnectionManager  - connection already null in cleanup : no action
2014-05-22 11:31:46,449 [http-bio-8080-exec-10] DEBUG impl.SessionImpl  - opened session at timestamp: 5737565005615104
2014-05-22 11:31:46,450 [http-bio-8080-exec-10] TRACE impl.SessionImpl  - closing session
2014-05-22 11:31:46,450 [http-bio-8080-exec-10] TRACE jdbc.ConnectionManager  - connection already null in cleanup : no action
2014-05-22 11:31:46,450 [http-bio-8080-exec-10] DEBUG impl.SessionImpl  - opened session at timestamp: 5737565005619200
2014-05-22 11:31:46,450 [http-bio-8080-exec-10] TRACE impl.SessionImpl  - closing session
2014-05-22 11:31:46,450 [http-bio-8080-exec-10] TRACE jdbc.ConnectionManager  - connection already null in cleanup : no action
2014-05-22 11:31:48,458 [http-bio-8080-exec-10] DEBUG impl.SessionImpl  - opened session at timestamp: 5737565013839872
2014-05-22 11:31:48,458 [http-bio-8080-exec-10] TRACE impl.SessionImpl  - closing session
2014-05-22 11:31:48,458 [http-bio-8080-exec-10] TRACE jdbc.ConnectionManager  - connection already null in cleanup : no action
2014-05-22 11:31:48,458 [http-bio-8080-exec-10] DEBUG impl.SessionImpl  - opened session at timestamp: 5737565013843968
2014-05-22 11:31:48,458 [http-bio-8080-exec-10] TRACE impl.SessionImpl  - closing session
2014-05-22 11:31:48,458 [http-bio-8080-exec-10] TRACE jdbc.ConnectionManager  - connection already null in cleanup : no action
2014-05-22 11:31:49,985 [http-bio-8080-exec-5] DEBUG jdbc.AbstractBatcher  - about to open ResultSet (open ResultSets: 0, globally: 0)
2014-05-22 11:31:49,986 [http-bio-8080-exec-5] TRACE loader.Loader  - processing result set
2014-05-22 11:31:49,986 [http-bio-8080-exec-5] TRACE loader.Loader  - done processing result set (0 rows)
2014-05-22 11:31:49,986 [http-bio-8080-exec-5] DEBUG jdbc.AbstractBatcher  - about to close ResultSet (open ResultSets: 1, globally: 1)
2014-05-22 11:31:49,986 [http-bio-8080-exec-5] DEBUG jdbc.AbstractBatcher  - about to close PreparedStatement (open PreparedStatements: 1, globally: 1)
2014-05-22 11:31:49,986 [http-bio-8080-exec-5] TRACE jdbc.AbstractBatcher  - closing statement
2014-05-22 11:31:49,986 [http-bio-8080-exec-5] TRACE loader.Loader  - total objects hydrated: 0
2014-05-22 11:31:49,986 [http-bio-8080-exec-5] DEBUG engine.StatefulPersistenceContext  - initializing non-lazy collections
2014-05-22 11:31:49,986 [http-bio-8080-exec-5] TRACE loader.Loader  - transformer=org.hibernate.transform.RootEntityResultTransformer returnTypes=[ REDACTED ] returnClasses=[ class REDACTED ]
2014-05-22 11:31:49,987 [http-bio-8080-exec-5] DEBUG transaction.JDBCTransaction  - commit
2014-05-22 11:31:49,987 [http-bio-8080-exec-5] TRACE impl.SessionImpl  - automatically flushing session
2014-05-22 11:31:49,987 [http-bio-8080-exec-5] TRACE def.AbstractFlushingEventListener  - flushing session
2014-05-22 11:31:49,987 [http-bio-8080-exec-5] REDACTED
2014-05-22 11:31:49,989 [http-bio-8080-exec-5] TRACE jdbc.ConnectionManager  - registering flush begin
2014-05-22 11:31:49,989 [http-bio-8080-exec-5] TRACE jdbc.ConnectionManager  - registering flush end
2014-05-22 11:31:49,989 [http-bio-8080-exec-5] TRACE def.AbstractFlushingEventListener  - post flush
2014-05-22 11:31:49,989 [http-bio-8080-exec-5] TRACE jdbc.JDBCContext  - before transaction completion
2014-05-22 11:31:49,989 [http-bio-8080-exec-5] TRACE impl.SessionImpl  - before transaction completion
2014-05-22 11:31:49,991 [http-bio-8080-exec-5] DEBUG transaction.JDBCTransaction  - re-enabling autocommit
2014-05-22 11:31:49,991 [http-bio-8080-exec-5] DEBUG transaction.JDBCTransaction  - committed JDBC Connection
2014-05-22 11:31:49,991 [http-bio-8080-exec-5] TRACE jdbc.JDBCContext  - after transaction completion
2014-05-22 11:31:49,991 [http-bio-8080-exec-5] DEBUG jdbc.ConnectionManager  - transaction completed on session with on_close connection release mode; be sure to close the session to release JDBC resources!
2014-05-22 11:31:49,992 [http-bio-8080-exec-5] TRACE impl.SessionImpl  - after transaction completion
2014-05-22 11:31:49,992 [http-bio-8080-exec-5] DEBUG impl.SessionImpl  - disconnecting session
2014-05-22 11:31:49,992 [http-bio-8080-exec-5] TRACE jdbc.ConnectionManager  - performing cleanup
2014-05-22 11:31:49,992 [http-bio-8080-exec-5] DEBUG jdbc.ConnectionManager  - releasing JDBC connection [ (open PreparedStatements: 0, globally: 0) (open ResultSets: 0, globally: 0)]
2014-05-22 11:31:49,992 [http-bio-8080-exec-5] TRACE jdbc.JDBCContext  - after transaction completion
2014-05-22 11:31:49,992 [http-bio-8080-exec-5] DEBUG jdbc.ConnectionManager  - transaction completed on session with on_close connection release mode; be sure to close the session to release JDBC resources!
2014-05-22 11:31:49,992 [http-bio-8080-exec-5] TRACE impl.SessionImpl  - after transaction completion
end time (millis): 1400772709992
difference: 38.225 seconds
******************* END HIBERNATE QUERY TRACE ********************

让我提醒您注意引起我们注意的内容--大约每2秒重复一次的六行--

打开的会话

然后

关闭会话

然后

连接已为空

，在一毫秒内完成两次

每隔2秒左右，Hibernate会打开并立即关闭2个会话？我的解释正确吗？在什么情况下会这样做

DataSource.groovy

中的数据源配置是基本的：

dataSource_REDACTED {
        driverClassName = 'oracle.jdbc.OracleDriver'
        dialect = 'org.hibernate.dialect.Oracle10gDialect'
        url = 'jdbc:oracle:thin:@REDACTED:1521/REDACTED'
        username = 'REDACTED'
        password = 'REDACTED'
        pooled = true
        properties {
            maxActive = 20
            minIdle = 1
            initialSize = 10
            testOnBorrow = true
            testWhileIdle = true
            validationQuery = "SELECT 1 FROM DUAL"
        }
}

这里没有

properties{}

块，因此使用诸如idle timeout之类的默认属性

同一文件中还有一个hibernate配置：

hibernate {
    cache.use_second_level_cache = true
    cache.use_query_cache = true
    cache.provider_class = 'net.sf.ehcache.hibernate.EhCacheProvider'
} 

正如我前面所说，我正在执行的条件查询非常简单：

withTransaction {
    List<MyAwesomeClass> awesomeThings = withCriteria {
        between("importantTime", startDate, endDate)
        eq("importantField", targetValue)
    }
 }

withTransaction{
列出awesomeThings=withCriteria{
介于（“重要时间”、开始日期、结束日期）之间
等式（“重要字段”，目标值）
}
}

criteria查询是从控制器直接调用的Grails域类中的方法运行的，而不是从事务服务运行的，因此我将其包装在

withTransaction

中

---

总之，这里的交易是什么？为什么在发生某些事情（不确定发生了什么）并实际执行了查询之前，还要处理会话呢？在尝试创建连接时，这可能与数据库本身的可用性有关吗？

这句话引起了我的注意：

transaction completed on session with on_close connection release mode; be sure to close the session to release JDBC resources! 
TRACE jdbc.JDBCContext  - after autocommit

根据：

ON_CLOSE-本质上是上述遗留行为。这个 Hibernate会话在第一次需要执行时获得连接 一些JDBC访问并保持该连接，直到会话结束 关闭

on_close-表示使用ConnectionReleaseMode.on_close。这个设置是 留作向后兼容性，但它的使用是非常不鼓励的

JPA确实允许您执行查询，即使您没有在事务中运行，但我不建议您使用此设置

我总是将所有Hibernate代码包装在事务中，对于只读操作，我选择readOnly=true标志

每个线程似乎都会依次打开和关闭两个会话，如果这是因为您运行了两个连续的查询，那么您可以通过在同一个会话中运行它们来优化它

因为您打开和关闭会话的速度非常快，所以您也在打开和关闭JDBC连接，并且您的设置不包含任何连接池。除非您使用连接池，否则创建和销毁连接将非常昂贵

查看我的应用程序，它可以显著提高应用程序性能

因此：

始终使用事务

使用连接池

---

事实上，我现在已经将查询包装在一个事务中，不幸的是在性能方面没有任何影响，即避免每两秒钟重新打开和关闭会话。我还应该提到，除了本地开发人员之外，我们在所有环境中都使用池数据源（是的，这是一致的，所以我应该做出更改），但是它们遇到相同的性能问题，所以我不认为池或缺少池是问题的一部分。也就是说，我将继续重新配置dev数据源，以使用连接池来消除这种差异。可悲的是，我所能做的就是以38秒的运行时间创造一个新记录。我还遗漏了其他一些东西：-/