Hibernate batch size confusion
This program does tens of thousands of consecutive inserts one after the other. I've never used Hibernate before. I'm getting extremely slow performance (if I just connect and execute the SQL manually I am 10-12x quicker. My batch_size is set to 50 as per many hibernate tutorials.
Here is a log from a single insert - perhaps you could help me understand exactly what is happening:
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.开发者_如何学编程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
When you call session.save(), hibernate will generate an INSERT SQL. This INSERT SQL will be appended to be issued to the DB during flushing (i.e session.flush()) .
During flushing, if hibernate.jdbc.batch_size is set to some non-zero value, Hibernate will use the batching feature introduced in the JDBC2 API to issue the batch insert SQL to the DB .
For example , if you save() 100 records and your hibernate.jdbc.batch_size is set to 50. During flushing, instead of issue the following SQL 100 times :
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 will group them in batches of 50 , and only issue 2 SQL to the DB, like this:
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')
Please note that Hibernate would disable insert batching at the JDBC level transparently if the primary key of the inserting table isGenerationType.Identity.
From your log: you save() only one record and then flush(), so there is only one appending INSERT SQL to be processed for every flush. That's why Hibernate cannot help you to batch inserting as there is only one INSERT SQL to be processed. You should save() up to the certain amount of records before calling flush() instead of calling flush() for every save().
The best practise of batch inserting is something like this:
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();
You save and flush the records batch by batch. In the end of each batch you should clear the persistence context to release some memory to prevent memory exhaustion as every persistent object is placed into the first level cache (your JVM's memory). You could also disable the second-level cache to reduce the unnecessary overhead.
Reference:
- Official Hibernate Documentation : Chapter 14. Batch processing
- Hibernate Batch Processing – Why you may not be using it. (Even if you think you are)
If you must use hibernate for huge batch jobs StatelessSession is the way to go. It strips things down to the most basic converting-objects-to-SQL-statements mapping and eliminates all of the overhead of the ORM features you're not using when just cramming rows into the DB wholesale.
It would also be much easier to make suggestions on your actual code than the log :)
11:02:56.133 [main] DEBUG o.h.transaction.JDBCTransaction - commit
This is saying that the database is committing after every insert. Ensure you are not committing your transaction / closing your session inside the insert loop. Do this once at the end instead.
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