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JBoss Reflect Performance Javassist vs Introspection
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reply from <a href="http://community.jboss.org/people/kabir.khan%40jboss.com">Kabir Khan</a> in <i>JBoss Microcontainer Development</i> - <a href="http://community.jboss.org/message/538459#538459">View the full discussion</a>
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<div class="jive-rendered-content"><p>I have implemented a first attempt at my five points above, but am still getting longer AS startup times with the javassist-based implementation of jboss-reflect than the introspection one.</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>I have added the possibility to record metrics of the invocation count and the invocation time, and an MBean to get hold of the results which look like this:</p><pre class="jive-pre"><code class="jive-code">Invocations (total time in ms) - Member name
============================================
1473 (0) - org.jboss.metadata.javaee.support.NamedMetaData.setName(Ljava/lang/String;)V - {G}
1281 (0) - org.jboss.metadata.web.spec.AttributeMetaData()V - {G}
1219 (0) - org.jboss.metadata.web.spec.AttributeMetaData.setRequired(Ljava/lang/String;)V - {G}
1132 (0) - org.jboss.metadata.javaee.spec.DescriptionImpl()V - {G}
1132 (3) - org.jboss.metadata.javaee.spec.DescriptionImpl.setDescription(Ljava/lang/String;)V - {G}
1127 (2) - org.jboss.metadata.javaee.spec.DescriptionsImpl()V - {G}
988 (0) - org.jboss.metadata.javaee.support.NamedMetaDataWithDescriptions.getDescriptions()Lorg/jboss/annotation/javaee/Descriptions; - {G}
988 (0) - org.jboss.metadata.javaee.support.NamedMetaDataWithDescriptions.setDescriptions(Lorg/jboss/annotation/javaee/Descriptions;)V - {G}
...
</code></pre><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>The time is not accurate, a lot of the invocations have a long "inherent time" such as org.hornetq.jms.server.impl.JMSServerManagerImpl.start(), and for simple setters the time is too short to be picked up. Anyway, the invocation count gives some idea of what is going on. I noticed that the bean metadata classes don't appear in this list, which is a bit strange so I need to figure out why that is.</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>By default, to avoid the overhead of generating classes for accessors that will not be used a lot, it is now set up to simply do what the introspection implementation does by default, which is to just invoke the members by reflection. The {G} and {R} after the member name indicates whether the accessor was generated or uses reflection. For frequently used accessors, I currently have a file called forceGenerate.txt in the bin/ folder of AS where you can specify which accessors should use a generated class:</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><pre class="jive-pre"><code class="jive-code">org.jboss.metadata.javaee.support.NamedMetaData.setName(Ljava/lang/String;)V
org.jboss.metadata.web.spec.AttributeMetaData()V
org.jboss.metadata.web.spec.AttributeMetaData.setRequired(Ljava/lang/String;)V
org.jboss.metadata.javaee.spec.DescriptionImpl()V
org.jboss.metadata.javaee.spec.DescriptionImpl.setDescription(Ljava/lang/String;)V
org.jboss.metadata.javaee.spec.DescriptionsImpl()V
org.jboss.metadata.javaee.support.NamedMetaDataWithDescriptions.getDescriptions()Lorg/jboss/annotation/javaee/Descriptions;
org.jboss.metadata.javaee.support.NamedMetaDataWithDescriptions.setDescriptions(Lorg/jboss/annotation/javaee/Descriptions;)V
org.jboss.metadata.web.spec.TagMetaData.getAttributes()Ljava/util/List;
org.jboss.metadata.web.spec.DeferredValueMetaData()V
org.jboss.metadata.web.spec.AttributeMetaData.setDeferredValue(Lorg/jboss/metadata/web/spec/DeferredValueMetaData;)V
org.jboss.metadata.web.spec.DeferredValueMetaData.setType(Ljava/lang/String;)V
org.jboss.metadata.web.spec.AttributeMetaData.setRtexprvalue(Ljava/lang/String;)V
</code></pre><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>Doing this for the top 10 used accessors improves the startup time very slightly, but it is still a lot slower than when using the introspection implementation. This leads me to thinking that something in this alternative implementation is playing a bigger part in slowing this down than the accessors. It could be something in the classpools, or maybe some inefficiencies in JavassistTypeInfo and related classes. I'll work on creating some benchmarks that can be run in AS and profile those to get a better idea of what is going on.</p></div>
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