hibernate second level ehcache miss problem

Question

Hi all

I'm trying to get a second-level hibernate cache working, using the ehcache implementation.

I'm sure it's some obvious noob mistake I'm making, but I can't see what it is!

To test out my cache, I'm doing the following:

Creating an object and saving it. I 'get' it once within the transaction, where I can see I get the object back without a db hit, which is just the hibernate first level cache doing its thing.

Then I commit the transaction and start a new session.

This time when I 'get' the object, I can see a cache miss from ehcache in the debugs. I would have expected the object to be in the cache now, since I saved it in the previous transaction?

Here's my code:

  Session session = getSession();   
  session.beginTransaction();

  Test1 test1a = new Test1();
  test1a.setId(5);
  test1a.setName("Test 1");
  test1a.setValue(10);
  // Touch it
  session.save(test1a);

  // Now get it
  Test1 test1b = (Test1)session.get(Test1.class, 5);

  // Within a transaction, the session caches it - no db hit
  System.out.println("GOT object with value "+test1b.getValue());

  session.getTransaction().commit();

  System.out.println("Between sessions");

  session = getSession();
  session.beginTransaction();

  test1b = (Test1)session.get(Test1.class, 5);

  System.out.println("GOT object with value "+test1b.getValue());

  session.getTransaction().commit(); 

And here's the relevant part of my hibernate.cfg.xml

<property name="cache.provider_class">org.hibernate.cache.EhCacheProvider</property>

And my ehcache.xml

<?xml version="1.0" encoding="UTF-8"?>
<ehcache xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="http://ehcache.sf.net/ehcache.xsd"&gt; 
<cache name="com.play.hibernate1.Test1" maxElementsInMemory="1000" eternal="false"     timeToLiveSeconds="600" overflowToDisk="false"/>
<defaultCache maxElementsInMemory="10000" eternal="false"

overflowToDisk="true" timeToIdleSeconds="10" timeToLiveSeconds="20" diskPersistent="true" />

And my annotations

@Entity
@Cache(usage = CacheConcurrencyStrategy.NONSTRICT_READ_WRITE)
public class Test1 {

And the debug logs

11:21:03,474 DEBUG CacheManager:239 - Configuring ehcache from classpath.
11:21:03,479 DEBUG ConfigurationFactory:122 - Configuring ehcache from ehcache.xml found in the classpath: file:/Users/bw/Documents/workspace/hibernate1/target/classes/ehcache.xml
11:21:03,479 DEBUG ConfigurationFactory:87 - Configuring ehcache from URL: file:/Users/brucewood/Documents/workspace/hibernate1/target/classes/ehcache.xml
11:21:03,480 DEBUG ConfigurationFactory:139 - Configuring ehcache from InputStream
11:21:03,485 DEBUG BeanHandler:213 - Ignoring ehcache attribute xmlns:xsi
11:21:03,485 DEBUG BeanHandler:213 - Ignoring ehcache attribute xsi:noNamespaceSchemaLocation
11:21:03,517 DEBUG ConfigurationHelper:208 - No CacheManagerEventListenerFactory class specified. Skipping...
11:21:03,518 DEBUG ConfigurationHelper:183 - No CachePeerListenerFactoryConfiguration specified. Not configuring a CacheManagerPeerListener.
11:21:03,518 DEBUG ConfigurationHelper:159 - No CachePeerProviderFactoryConfiguration specified. Not configuring a CacheManagerPeerProvider.
11:21:03,525 DEBUG ConfigurationHelper:135 - No BootstrapCacheLoaderFactory class specified. Skipping...
11:21:03,526 DEBUG ConfigurationHelper:135 - No BootstrapCacheLoaderFactory class specified. Skipping...
11:21:03,532 DEBUG MemoryStore:73 - Initialized net.sf.ehcache.store.LruMemoryStore for com.play.hibernate1.Test1
11:21:03,533 DEBUG LruMemoryStore:71 - com.play.hibernate1.Test1 Cache: Using SpoolingLinkedHashMap implementation
11:21:03,533 DEBUG Cache:429 - Initialised cache: com.play.hibernate1.Test1
1528 [Finalizer] INFO org.hibernate.connection.DriverManagerConnectionProvider - cleaning up connection pool: jdbc:mysql://localhost:3306/play
1668 [main] INFO org.hibernate.impl.SessionFactoryObjectFactory - Not binding factory to JNDI, no JNDI name configured
GOT object with value 10
Hibernate: 
    /* insert com.play.hibernate1.Test1
        */ insert 
        into
            Test1
            (name, value, id) 
        values
            (?, ?, ?)
1274984463818|1|1|batch|/* insert com.play.hibernate1.Test1 */ insert into Test1 (name, value, id) values (?, ?, ?)|/* insert com.play.hibernate1.Test1 */ insert into Test1 (name, value, id) values ('Test 1', 10, 5)
1274984463820|1|1|statement|/* insert com.play.hibernate1.Test1 */ insert into Test1 (name, value, id) values (?, ?, ?)|/* insert com.play.hibernate1.Test1 */ insert into Test1 (name, value, id) values ('Test 1', 10, 5)
1274984463821|1|1|commit||
Between sessions
11:21:03,823 DEBUG EhCache:68 - key: com.play.hibernate1.Test1#5
11:21:03,823 DEBUG MemoryStore:138 - com.play.hibernate1.Test1Cache: com.play.hibernate1.Test1MemoryStore miss for com.play.hibernate1.Test1#5
11:21:03,823 DEBUG Cache:661 - com.play.hibernate1.Test1 cache - Miss
11:21:03,824 DEBUG EhCache:77 - Element for com.play.hibernate1.Test1#5 is null
Hibernate: 
    /* load com.play.hibernate1.Test1 */ select
        test1x0_.id as id0_0_,
        test1x0_.name as name0_0_,
        test1x0_.value as value0_0_ 
    from
        Test1 test1x0_ 
    where
        test1x0_.id=?
1274984463829|4|1|statement|/* load com.play.hibernate1.Test1 */ select test1x0_.id as id0_0_, test1x0_.name as name0_0_, test1x0_.value as value0_0_ from Test1 test1x0_ where test1x0_.id=?|/* load com.play.hibernate1.Test1 */ select test1x0_.id as id0_0_, test1x0_.name as name0_0_, test1x0_.value as value0_0_ from Test1 test1x0_ where test1x0_.id=5
1274984463831|-1||resultset|/* load com.play.hibernate1.Test1 */ select test1x0_.id as id0_0_, test1x0_.name as name0_0_, test1x0_.value as value0_0_ from Test1 test1x0_ where test1x0_.id=5|name0_0_ = Test 1, value0_0_ = 10
GOT object with value 10
1274984463834|0|1|commit||

Thanks for your help!

Answer 1

The problem was that I was using NONSTRICT_READ_WRITE. It seemed to fit the bill from this explanation in the docs:

If the application only occasionally needs to update data (i.e. if it is extremely unlikely that two transactions would try to update the same item simultaneously), and strict transaction isolation is not required, a nonstrict-read-write cache might be appropriate. If the cache is used in a JTA environment, you must specify hibernate.transaction.manager_lookup_class. In other environments, you should ensure that the transaction is completed when Session.close() or Session.disconnect() is called.

but actually it looks like it doesn't add saved objects to the cache.. Docs are a little thin here, IMO. There is a better treatment of the caching options in Java Persistence with Hibernate, although still a little thin on concrete explanation of what actually happens to your data. Anyway..

I changed my caching option to READ_WRITE, and now it works as expected.

Note also that the first time an object gets added to the cache, you get a 'cache miss' in the ehcache debugs. Presumably it looks in its cache, finds the object is not there, records a miss, then adds the object. After that, you get 'hits'.