该程序一个接一个地执行数以万计的连续插入。我以前从未使用过Hibernate。我的性能变得非常慢（如果我只是手动连接并执行SQL，我的速度会提高10-12倍。根据许多hibernate教程，我的batch_size设置为50。
这是单个插入的日志-也许您可以帮助我准确了解正在发生的事情：
START INSERT 11:02:56.121 [main] DEBUG org.hibernate.impl.SessionImpl - opened session at timestamp: 13106053761 11:02:56.121 [main] DEBUG o.h.transaction.JDBCTransaction - begin 11:02:56.121 [main] DEBUG org.hibernate.jdbc.ConnectionManager - opening JDBC connection 11:02:56.121 [main] TRACE o.h.c.DriverManagerConnectionProvider - total checked-out connections: 0 11:02:56.121 [main] TRACE o.h.c.DriverManagerConnectionProvider - using pooled JDBC connection, pool size: 0 11:02:56.121 [main] DEBUG o.h.transaction.JDBCTransaction - current autocommit status: false 11:02:56.121 [main] TRACE org.hibernate.jdbc.JDBCContext - after transaction begin 11:02:56.121 [main] TRACE org.hibernate.impl.SessionImpl - setting flush mode to: MANUAL 11:02:56.121 [main] TRACE o.h.e.def.DefaultLoadEventListener - loading entity: [com.xyzcompany.foo.edoi.ejb.msw000.MSW000Rec#component[keyW000]{keyW000=F000 ADSUFC}] 11:02:56.121 [main] TRACE o.h.e.def.DefaultLoadEventListener - creating new proxy for entity 11:02:56.122 [main] TRACE o.h.e.d.DefaultSaveOrUpdateEventListener - saving transient instance 11:02:56.122 [main] DEBUG o.h.e.def.AbstractSaveEventListener - generated identifier: component[keyW000]{keyW000=F000 ADSUFC}, using strategy: org.hibernate.id.CompositeNestedGeneratedValueGenerator 11:02:56.122 [main] TRACE o.h.e.def.AbstractSaveEventListener - saving [com.xyzcompany.foo.edoi.ejb.msw000.MSW000Rec#component[keyW000]{keyW000=F000 ADSUFC}] 11:02:56.123 [main] TRACE o.h.e.d.AbstractFlushingEventListener - flushing session 11:02:56.123 [main] DEBUG o.h.e.d.AbstractFlushingEventListener - processing flush-time cascades 11:02:56.123 [main] DEBUG o.h.e.d.AbstractFlushingEventListener - dirty checking collections 11:02:56.123 [main] TRACE o.h.e.d.AbstractFlushingEventListener - Flushing entities and processing referenced collections 11:02:56.125 [main] TRACE o.h.e.d.AbstractFlushingEventListener - Processing unreferenced collections 11:02:56.125 [main] TRACE o.h.e.d.AbstractFlushingEventListener - Scheduling collection removes/(re)creates/updates 11:02:56.126 [main] DEBUG o.h.e.d.AbstractFlushingEventListener - Flushed: 1 insertions, 0 updates, 0 deletions to 62 objects 11:02:56.126 [main] DEBUG o.h.e.d.AbstractFlushingEventListener - Flushed: 0 (re)creations, 0 updates, 0 removals to 0 collections 11:02:56.132 [main] TRACE o.h.e.d.AbstractFlushingEventListener - executing flush 11:02:56.132 [main] TRACE org.hibernate.jdbc.ConnectionManager - registering flush begin 11:02:56.132 [main] TRACE o.h.p.entity.AbstractEntityPersister - Inserting entity: [com.xyzcompany.foo.edoi.ejb.msw000.MSW000Rec#component[keyW000]{keyW000=F000 ADSUFC}] 11:02:56.132 [main] DEBUG org.hibernate.jdbc.AbstractBatcher - about to open PreparedStatement (open PreparedStatements: 0, globally: 0) 11:02:56.132 [main] DEBUG org.hibernate.SQL - insert into MSW000 (W000_DATA_REC, W000_FILE_FLAGS, KEY_W000) values (?, ?, ?) 11:02:56.132 [main] TRACE org.hibernate.jdbc.AbstractBatcher - preparing statement 11:02:56.132 [main] TRACE o.h.p.entity.AbstractEntityPersister - Dehydrating entity: [com.xyzcompany.foo.edoi.ejb.msw000.MSW000Rec#component[keyW000]{keyW000=F000 ADSUFC}] 11:02:56.132 [main] TRACE org.hibernate.type.StringType - binding ' ADSUFCA ' to parameter: 1 11:02:56.132 [main] TRACE org.hibernate.type.StringType - binding ' ' to parameter: 2 11:02:56.132 [main] TRACE org.hibernate.type.StringType - binding 'F000 ADSUFC' to parameter: 3 11:02:56.132 [main] DEBUG org.hibernate.jdbc.AbstractBatcher - Executing batch size: 1 11:02:56.133 [main] DEBUG org.hibernate.jdbc.AbstractBatcher - about to close PreparedStatement (open PreparedStatements: 1, globally: 1) 11:02:56.133 [main] TRACE org.hibernate.jdbc.AbstractBatcher - closing statement 11:02:56.133 [main] TRACE org.hibernate.jdbc.ConnectionManager - registering flush end 11:02:56.133 [main] TRACE o.h.e.d.AbstractFlushingEventListener - post flush 11:02:56.133 [main] DEBUG o.h.transaction.JDBCTransaction - commit 11:02:56.133 [main] TRACE org.hibernate.impl.SessionImpl - automatically flushing session 11:02:56.133 [main] TRACE org.hibernate.jdbc.JDBCContext - before transaction completion 11:02:56.133 [main] TRACE org.hibernate.impl.SessionImpl - before transaction completion 11:02:56.133 [main] DEBUG o.h.transaction.JDBCTransaction - committed JDBC Connection 11:02:56.133 [main] TRACE org.hibernate.jdbc.JDBCContext - after transaction completion 11:02:56.133 [main] DEBUG org.hibernate.jdbc.ConnectionManager - transaction completed on session with on_close connection release mode; be sure to close the session to release JDBC resources! 11:02:56.133 [main] TRACE org.hibernate.impl.SessionImpl - after transaction completion 11:02:56.133 [main] TRACE org.hibernate.impl.SessionImpl - closing session 11:02:56.133 [main] TRACE org.hibernate.jdbc.ConnectionManager - performing cleanup 11:02:56.133 [main] DEBUG org.hibernate.jdbc.ConnectionManager - releasing JDBC connection [ (open PreparedStatements: 0, globally: 0) (open ResultSets: 0, globally: 0)] 11:02:56.133 [main] TRACE o.h.c.DriverManagerConnectionProvider - returning connection to pool, pool size: 1 11:02:56.133 [main] TRACE org.hibernate.jdbc.JDBCContext - after transaction completion 11:02:56.133 [main] DEBUG org.hibernate.jdbc.ConnectionManager - transaction completed on session with on_close connection release mode; be sure to close the session to release JDBC resources! 11:02:56.134 [main] TRACE org.hibernate.impl.SessionImpl - after transaction completion FINISH INSERT
当您调用时session.save()，hibernate将生成一个INSERT SQL。该INSERT SQL将附加在刷新（即session.flush()）期间发布给数据库。
session.save()
session.flush()
在刷新过程中，如果hibernate.jdbc.batch_size将其设置为某个非零值，则Hibernate将使用JDBC2 API中引入的批处理功能向数据库发出批处理插入SQL。
hibernate.jdbc.batch_size
例如，如果您有save()100条记录，而您的记录hibernate.jdbc.batch_size设置为50。在刷新期间，请不要发出以下SQL 100次：
save()
insert into TableA (id , fields) values (1, 'val1'); insert into TableA (id , fields) values (2, 'val2'); insert into TableA (id , fields) values (3, 'val3'); ......................... insert into TableA (id , fields) values (100, 'val100');
Hiberate将它们分为50个批次，并且仅向数据库发出2条SQL，如下所示：
insert into TableA (id , fields) values (1, 'val1') , (2, 'val2') ,(3, 'val3') ,(4, 'val4') ,......,(50, 'val50') insert into TableA (id , fields) values (51, 'val51') , (52, 'val52') ,(53, 'val53') ,(54, 'val54'),...... ,(100, 'val100')
请注意，如果插入表的主键为，则Hibernate将透明地禁用JDBC级别的插入批处理GenerationType.Identity。
GenerationType.Identity
从您的日志中：您save()只有一条记录，然后是flush()，因此对于每次刷新，仅要处理一条附加的INSERTSQL。这就是Hibernate无法帮助您批量插入的原因，因为只有一个INSERT SQL要处理。save()在调用之前，您应该最多保留一定数量的记录，flush()而不是flush()每次调用save()。
flush()
批处理插入的最佳实践是这样的：
Session session = sessionFactory.openSession(); Transaction tx = session.beginTransaction(); for ( int i=0; i<888888; i++ ) { TableA record = new TableA(); record.setXXXX(); session.save(record) if ( i % 50 == 0 ) { //50, same as the JDBC batch size //flush a batch of inserts and release memory: session.flush(); session.clear(); } } tx.commit(); session.close();
您分批保存并刷新记录。在每个批处理的最后，您应该清除持久性上下文以释放一些内存，以防止将每个持久性对象都放入第一级缓存（JVM的内存）时导致内存耗尽。您也可以禁用二级缓存以减少不必要的开销。
参考：
