[Hibernate-issues] [Hibernate-JIRA] Commented: (HHH-1490) QueryCache should not call EntityType.getReturnedClass() or do it fast

[Emmanuel B. (JIRA) <no...@at...>]

    [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-1490?page=comments#action_23505 ] 

Emmanuel Bernard commented on HHH-1490:
---------------------------------------

Why is it expensive? The method call is basically hitting the classloader cache which is kind of a native hash map

> QueryCache should not call EntityType.getReturnedClass() or do it fast
> ----------------------------------------------------------------------
>
>          Key: HHH-1490
>          URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-1490
>      Project: Hibernate3
>         Type: Improvement

>   Components: core
>     Versions: 3.1.2
>  Environment: Hibernate 3.1.2, MySQL 5.0.18-nt
>     Reporter: Sergey Vladimirov
>     Priority: Minor
>  Attachments: patch.txt
>
>
> org.hibernate.cache.QueryKey should not call EntityType.getReturnedClass() or do it fast, because EntityType.getReturnedClass() works with ClassLoader - i is very expensive operation:
> Stack trace: 
> java.lang.ClassLoader.findLoadedClass0(Native Method)
> java.lang.ClassLoader.findLoadedClass(ClassLoader.java:922)
> java.lang.ClassLoader.loadClass(ClassLoader.java:295)
>    - locked sun.misc.Launcher$AppClassLoader@93dee9
> sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:276)
>    - locked sun.misc.Launcher$AppClassLoader@93dee9
> java.lang.ClassLoader.loadClass(ClassLoader.java:251)
> org.hibernate.util.ReflectHelper.classForName(ReflectHelper.java:95)
> org.hibernate.type.EntityType.getReturnedClass(EntityType.java:91)
> org.hibernate.cache.QueryKey.equals(QueryKey.java:59)
> org.apache.commons.collections.map.AbstractReferenceMap.isEqualKey(AbstractReferenceMap.java:433)
> org.apache.commons.collections.map.AbstractHashedMap.getEntry(AbstractHashedMap.java:434)
> org.apache.commons.collections.map.AbstractReferenceMap.getEntry(AbstractReferenceMap.java:404)
> org.apache.commons.collections.map.AbstractReferenceMap.get(AbstractReferenceMap.java:229)
> ru.arptek.common.collections.SynchronizedMap.get(SynchronizedMap.java:94)
> Operations with ClassLoaders is not falst enought for equals() operations. May be one should add some kind of caching (in EntityType, for example) or compare EntityType by class names, not by Class objects.

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