Spring JDBCTemplate Vs Hibernate Performance + JPA & Caching

Spring JDBCTemplate Vs Hibernate Performance

If you do all you can to make Spring JDBCTemplate / Hibernate implementations very fast, the JDBC template will probably be a bit faster, because it doesn't have the overhead that Hibernate has, but it will probably take much more time and lines of code to implement.

Hibernate has its learning curve, and you have to understand what happens behind the scenes, when to use projections instead of returning entities, etc. But if you master it, you'll gain much time and have cleaner and simpler code than with a JDBC-based solution.

In 95% of the cases, Hibernate is fast enough, or even faster than non-optimized JDBC code. For the 5% left, nothing forbids you to use something else, like Spring-JDBC for example. Both solutions are not mutually exclusive.

Hibernate

Hibernate is not intended for batch-jobs, it is an anti patterns of O/R Mapper usage.  Even the Hibernate documentation warns to not do that. Batch processing often can be much more easily done by a single clever SQL statement instead via O/R mappers which need a bunch of statements to do the same. Not because they are bad, but because they have not been built for this use case. Data is always by default loaded lazyly in Hibernate.

One of the common problems of people that start using Hibernate is performance, if you don’t have much experience in Hibernate you will find how quickly your application becomes slow. If you enable sql traces, you would see how many queries are sent to database that can be avoided with little Hibernate knowledge. Good use of Hibernate Cache to avoid amount of traffic between your application and database.

JPA + Spring

If you are using spring and JPA, it is very likely that you utilize ehcache (or another cache provider). And you do that in two separate scenarios: JPA 2nd level cache and spring method caching.

When you configure your application, you normally set the 2nd level cache provider of your JPA provider (hibernate, in my case) and you also configure spring with the “cache” namespace. Everything looks OK and you continue with the project. But there’s a caveat. If you follow the most straightforward way, you get two separate cache managers which load the same cache configuration file. This is not bad per-se, but it is something to think about – do you really need two cache manager and the problems that may arise from this

JPA & Caching

Caching is the most important performance optimization technique. There are many things that can be cached in persistence, objects, data, database connections, database statements, query results, meta-data, relationships, to name a few. Caching in object persistence normally refers to the caching of objects or their data.

Caching also influences object identity, that is that if you read an object, then read the same object again you should get the identical object back (same reference).

JPA 1.0 does not define a shared object cache, JPA providers can support a shared object cache or not, however most do.

Caching in JPA is required with-in a transaction or within an extended persistence context to preserve object identity, but JPA does not require that caching be supported across transactions or persistence contexts.

JPA 2.0 defines the concept of a shared cache. The @Cacheable annotation or cacheable XML attribute can be used to enable or disable caching on a class.

Hibernate cache

Cache Types : Hibernate uses different types of caches. Each type of cache is used for different purposes. Let us first have a look at this cache types.

The first cache type is the session cache. The session cache caches object within the current session.
The second cache type is the query Cache. The query cache is responsible for caching queries and their results.
The third cache type is the second level cache. The second level cache is responsible for caching objects across sessions.

The Session Cache
session cache caches values within the current session.  This cache is enabled by default.

The Query Cache
The query cache can be really usefull to optimize the performance of your data access layer. However there are a number of pitfalls as well.  This blog post describes a serious problem regarding memory consumption of the Hibernate query cache when using objects as parameters. It could consumpt ton of memories and hit
OutOfMemoryError (How to fix it)

The Second Level Cache
The key characteristic of the second-level cache is that is is used across sessions, which also differentiates it from the session cache, which only – as the name says – has session scope. Hibernate provides a flexible concept to exchange cache providers for the second-level cache. By default Ehcache is used as caching provider.

However more sophisticated caching implementation can be used like the distributed JBoss Cache or Oracle Coherence.

Additional readings:

Understanding caching in hibernate (1 | 2 | 3) , tutorial and tuning

Top 10 Performance Problems taken from Zappos, Monster, Thomson and Co

52 weeks of Application Performance – The dynaTrace Almanac