[hibernate-issues] [Hibernate-JIRA] Created: (HHH-3909) Improve Performance of FieldInterceptionHandler (and thus of flushing)

[Ovidio Mallo (JIRA)]

Improve Performance of FieldInterceptionHandler (and thus of flushing)
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                 Key: HHH-3909
                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-3909
             Project: Hibernate Core
          Issue Type: Improvement
          Components: core
    Affects Versions: 3.3.1
            Reporter: Ovidio Mallo
         Attachments: patch.txt

In the FieldInterceptionHelper class, the method Class#getInterfaces() is used in conjunction with a subsequent loop over all interfaces of an entity class in order to check whether a bytecode instrumentation interface of CGlib or Javassist is found. This is done that way since CGlib and Javassist are both optional so they should only be accessed at runtime if available on the classpath. Attached you can find a simple patch which only once checks whether CGlib and/or Javassist is available and then uses the more performant "instanceof" operator in order to check whether an entity has an interceptor. The new code still guarantees that no CGlib or Javassist class is accessed if it is not on the classpath.

The patch helps making the FieldInterceptionHelper methods more performant which can e.g. be noticed during a session flush, especially if bytecode instrumentation is used. In order to measure the performance impact of the patch I've written a simple program which does the following:
1. insert 100 thousand entities into a simple table with 6 numeric attributes
2. do an initial flush on the session in order to execute all the insert statements
3. loop 300 times and do a flush on the session (only a dirty check is performed, no database operation)

I've time the flushes under point 3 above with and without bytecode instrumentation for the used entity. Here are the results:

USING BYTECODE INSTRUMENTATION
=============================
* SUN JVM 1.6.0_05:
  - without patch:  25734ms
  - with patch:     11015ms
* IBM JVM 1.4.2:
  - without patch:  20672ms
  - with patch:     11140ms


WITHOUT BYTECODE INSTRUMENTATION
================================
* SUN JVM 1.6.0_05:
  - without patch:  73328ms
  - with patch:     62015ms
* IBM JVM 1.4.2:
  - without patch:  70344ms
  - with patch:     61125ms

Using bytecode instrumentation, the performance improvement is about of a factor of 2-2.5. When not using bytecode instrumentation, the overall impact is of course less relevant since the rest of the work done during flush is more expensive anyway. In any case, IMHO the impact when using bytecode instrumentation is relevant.

The patch is very simple and only touches the FieldInterceptionHelper class.

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