Hi
I'm new to tomcat/hibernate and I want to use ehcache 3.
I followed many tutorials and samples on the web, but could not make it work. The application itself works perfectly but all queries are sent to mysql, none are cached. Any help will be greatly appreciated.

Main libraries :
ehcache-3.3.1.jar
ehcache-api-3.3.1.jar
ehcache-core-3.3.1.jar
hibernate-commons-annotations-5.0.1.Final.jar
hibernate-core-5.2.10.Final.jar
hibernate-jcache-5.2.10.Final.jar
hibernate-jpa-2.1-api-1.0.0.Final.jar
etc.

persistence.xml:


Persistent object :


Application code :


=> both queries are sent to mysql (shown in mysql server log)

I tried to add but it did not change.
I tried to add a minimal ehcache.xml but it did not change.
I don't understand why there is no caching, and why there is absolutely no error in logs...

The small sample is here with full code and IntelliJ Project: https://www.5flow.com/tmp/ehcache-2017-10-12.zip
Thanks.

As I explained in this article, you need to set the following property as well:



And, you need to enable the query cache for every query as follows:



Otherwise, it will not work.

Hi vlad, thanks for your answer.
As you can see it in my topic text, I did both what you suggest, and it still does not work (see the downloadable full sample project also).
Thanks

How do you know it does not work? Did you activate the SQL log?

Check out this article For more info about the best way to log JDBC statements:

https://vladmihalcea.com/the-best-way-t ... tatements/

Hello vlad

I did not activate Hibernate sql Logging in persistence.xml (<property name="hibernate.show_sql" value="false"/>) because as far as I understand, it displays sql request even if the request is not sent to mysql when data comes from the cache. I did not activate sql logging in context.xml/<Resource> database url (profileSQL=true) because it displays huge stack trace not really readable.

I activated mysql logging directly in mysql : (set global general_log='on') which shows exactly all real requests received in the database.

My 2 last search in code :



Produces this log in Mysql :



Which means that Mysql received exactly twice the same request while the second should be cached.
Thanks

I have a test on GitHub which proves that the Query Cache works just fine. Fork my repository and debug it along with your code and see where they diverge.

Also, I'm using the Ehcache directly not through JCache:



Although, I doubt it's because of that.

They way you concatenate Strings when building the SQL query is also wrong:



You should never do that because you can risk SQL Injection attacks.

Hello vlad

Don't worry about sql injection, this is only a sample, in my application I always use ":id" parameters

I tried to replace org.hibernate.cache.jcache.JCacheRegionFactory by org.hibernate.cache.ehcache.EhCacheRegionFactory but this class is not provided in libraries I included in my project (see my first post) :

Caused by: org.hibernate.boot.registry.selector.spi.StrategySelectionException: Unable to resolve name [org.hibernate.cache.ehcache.EhCacheRegionFactory] as strategy [org.hibernate.cache.spi.RegionFactory]

There is a maven library org.hibernate:hibernate-ehcache:5.2.11.Final which contains this class, but it uses ehcache 2.10 instead of 3.4 , an bit old no ! I tried anyway with this one, the application compiles correctly now, but the sql requests are sent twice to Mysql again, there is no 2nd level cache activated from my point of view.

I downloaded your sample on GitHub, but could not make it run, the class itself does not work alone, and the full project is very complex, I could not find the way to run the cache test correctly. (many errors that I'm not able to understand). By the way your sample use ehcache version 2, not 3. : <ehcache.version>2.6.9</ehcache.version>

I have no doubt that EhCache 2nd level cache works perfectly with Hibernate of course ! All I want is to make it work in my little sample.

Is there any chance that someone download the sample at https://www.5flow.com/tmp/ehcache-2017-10-12.zip and tell me what's wrong ? (it has only one class, with one little test, very few dependencies and can be opened and run directly in intellij in seconds)

Thanks a lot.

Your project does not feature Maven so it takes way too much time to configure it, and it features no JUnit tests to rapidly figure out what's wrong.

What you can do is to isolate the data access code using the Hibernate unit test templates and figure out where you did it wrong.

Cheers.

Hello vlad

I downloaded the hibernate unit test template which was very useful.
I wrote a little unit test with 2 identical queries. I made also exactly the same program within tomcat 8.5.

Both programs use (quite) exactly the same source code, exactly the same persistence.xml, the same jars with same versions, the same database driver, the same database schema and the same entity bean.

When running in junit, ehcache is working and the second request is not sent to mysql
When running in tomcat, the second request is sent to mysql, ehcache is not activated.

Can you imagine a reason for that ?
Both projects are available here : https://www.5flow.com/tmp/ehcache-2017-19-16.zip

Should I go to tomcat users mailing list ?
Thanks

It's good that you have both tests in place now. What you can do is debug both of them to see why the Unit Test works while the web-app does not.

I can only suspect that the properties are not loaded or they are loaded from a different place or something like that.

It makes no sense to ask on the Tomcat forum, it's not like this is a Tomcat issue. It's just your particular application settings that are causing the problem.

Therefore, just debug it and see why it does not work. You will find a way where they diverge.

The properties seems all right to me. But I think I found...thanks to your suggestion.

I entered "qr.getResultList()", IntelliJ decompiles for me the .class files... deep inside unknown world !!!
In Tomcat, the queryCache is correctly loaded in hibernate.loader.Loader.listUsingQueryCache() , just like in junit. But I found that there was a difference at UpdateTimestampsCache.isUpToDate() ! So I had the idea that in junit, there are 2 entity managers created, one for each test, while in tomcat there is only one. After some tests I found the following conclusion :

In tomcat AND in junit, this code:



produces the following mysql requests :



while this code (commenting the close/create in the middle):



produces the follwing queries in mysql :



I don't understand the reason for that. Why should I close the entity manager between the add and the query ? As long as the commit is done I should be able to use the same entity manager for all my queries ? (in one http request).
Here the code that demonstrated double request to mysql with junit template : https://www.5flow.com/tmp/ehcache-2017-10-16.2.zip

Thanks for any explanation...

Just use Spring Transaction Manager and inject the Persistence Context and let Spring take care of EntityManager and Transaction lifecycle.

It makes no sense to do it manually as you are doing it now. You rarely need to bootstrap Hibernate natively. Just use Spring or Java EE and you won't have to deal with all these issues.

Sorry but we decided not to use Spring. Spring is a great tool and help developers in many cases, but from our point of view, and for the current projet, it is too difficult to learn and understand, and it seems that we don't really need it. Maybe we're wrong, but until now we could not find anything that changed our choice.

If what I found here is a normal behaviour with Hibernate/EhCache, I'm not sure we'll use Hibernate either. I expect a JPA implementation to be simple to use and simple to configure, like I used to do in a past projects with Caucho's Resin that provided EclipseLink.

If there is no workaround, I'll stop now my investigation on Hibernate/EhCache. If there is one, please give me a clue.
Thanks

Spring is anything but difficult to learn, and it takes care of all the bootstrapping logic you are struggling with now.



As you already experienced when doing the Unit Tests, as long as the configuration is properly done, you will have no issue. However, your manual configuration is wrong.



This is not related to Hibernate. Most likely it's a web app config issue. Even if you didn't use Hibernate/EhCache, you'd still have issues with other frameworks if the problem is related to the web app config.

Well, I'm probably too ignorant or too old :) to understand Spring. Its configuration seemed very difficult to me, from the readings and from trying tutorials and samples (from spring site and others) that simply did not work at all.

From my point of view, if there is a configuration problem, there must be a configuration somewhere to fix that should be documented on ehcache site or hibernate site, and I could not find that. I did exactly what tutorials about Hibernate/EhCache suggested, and found no other information on how to configure more for ehcache in hibernate. It was actually already difficult to find configuration information for latest versions of hibernate and ehcache, because most forums talked about old versions.

I wish to thank you very much for your help, I appreciated the time you spent helping me.