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    JBoss Reflect Performance Javassist vs Introspection
</h3>
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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/537476#537476">View the full discussion</a>
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<div class="jive-rendered-content"><p>What we generate is effectively something along the lines of</p><p style="min-height: 8pt; height: 8pt; padding: 0px;">&#160;</p><pre class="jive-pre"><code class="jive-code jive-java"><font color="navy"><b>public</b></font> <font color="navy"><b>class</b></font> JavassistMethod1 <font color="navy"><b>implements</b></font> JavassistMethod
<font color="navy">{</font>
&#160;&#160; <font color="navy"><b>public</b></font> Object invoke(Object target, Object[] args) <font color="navy"><b>throws</b></font> Throwable
&#160;&#160; <font color="navy">{</font>
&#160;&#160;&#160;&#160;&#160; <font color="navy"><b>if</b></font> (target == <font color="navy"><b>null</b></font>)
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; <font color="navy"><b>throw</b></font> <font color="navy"><b>new</b></font> IllegalArgumentException(<font color="red">"Null target"</font>);
&#160;&#160;&#160;&#160;&#160; <font color="navy"><b>if</b></font> (target <font color="navy"><b>instanceof</b></font> SomeClass == <font color="navy"><b>false</b></font>)
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; <font color="navy"><b>throw</b></font> <font color="navy"><b>new</b></font> IllegalArgumentException(<font color="red">"Wrong target"</font>);
&#160;&#160;&#160;&#160;&#160; 
&#160;&#160;&#160;&#160;&#160; <font color="navy"><b>if</b></font> (args == <font color="navy"><b>null</b></font> || args.length != 10) 
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; <font color="navy"><b>throw</b></font> <font color="navy"><b>new</b></font> IllegalArgumentException(<font color="red">"Wrong number of parameters"</font>);
&#160;&#160;&#160;&#160;&#160; 
&#160;&#160;&#160;&#160;&#160; <font color="navy"><b>if</b></font> (args[0] == <font color="navy"><b>null</b></font>) 
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; <font color="navy"><b>throw</b></font> <font color="navy"><b>new</b></font> IllegalArgumentException(<font color="red">"Parameter 1 cannot be null for SomeClass.someMethod(long, String)"</font>);
&#160;&#160;&#160;&#160;&#160; <font color="navy"><b>if</b></font> (args[0] != <font color="navy"><b>null</b></font> &amp;&amp; args[0] <font color="navy"><b>instanceof</b></font> Long == <font color="navy"><b>false</b></font>) 
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; <font color="navy"><b>throw</b></font> <font color="navy"><b>new</b></font> IllegalArgumentException(<font color="red">"Parameter 1 is not an instance of Long for SomeClass.someMethod(long, String)"</font>);
&#160;&#160;&#160;&#160;&#160; 
&#160;&#160;&#160;&#160;&#160; <font color="navy"><b>if</b></font> (args[1] != <font color="navy"><b>null</b></font> &amp;&amp; args[1] <font color="navy"><b>instanceof</b></font> String == <font color="navy"><b>false</b></font>) 
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; <font color="navy"><b>throw</b></font> <font color="navy"><b>new</b></font> IllegalArgumentException(<font color="red">"Parameter 2 is not an instance of String for SomeClass.someMethod(long, String)"</font>);
&#160;&#160;&#160;&#160;&#160; 
&#160;&#160;&#160;&#160;&#160; <font color="navy"><b>return</b></font> ((SomeClass)target).someMethod(((Long)args[0]).longValue(), (String)args[1]);&#160;&#160;&#160;&#160;&#160; 
&#160;&#160; <font color="navy">}</font>
<font color="navy">}</font>
</code></pre><p style="min-height: 8pt; height: 8pt; padding: 0px;">&#160;</p><p>Disabling the parameter checking so we end up with this instead reduces the time spent in C from about 4.8s to 3.8s</p><p style="min-height: 8pt; height: 8pt; padding: 0px;">&#160;</p><pre class="jive-pre"><code class="jive-code jive-java"><font color="navy"><b>public</b></font> <font color="navy"><b>class</b></font> JavassistMethod1 <font color="navy"><b>implements</b></font> JavassistMethod
<font color="navy">{</font>
&#160;&#160; <font color="navy"><b>public</b></font> Object invoke(Object target, Object[] args) <font color="navy"><b>throws</b></font> Throwable
&#160;&#160; <font color="navy">{</font>
&#160;&#160;&#160;&#160;&#160; <font color="navy"><b>return</b></font> ((SomeClass)target).someMethod(((Long)args[0]).longValue(), (String)args[1]);&#160;&#160;&#160;&#160;&#160; 
&#160;
&#160;&#160; <font color="navy">}</font>
<font color="navy">}</font> 
&#160;
</code></pre><p style="min-height: 8pt; height: 8pt; padding: 0px;">&#160;</p><p>Profiling this, for each JavassistMethod implementation the time taken is roughly</p><p style="min-height: 8pt; height: 8pt; padding: 0px;">&#160;</p><p>50% generating the bytecode for the method </p><p>30% Converting the bytecode to a byte array and creating the class</p><p>13% creating the constructor</p><p>6% setting the interfaces</p><p style="min-height: 8pt; height: 8pt; padding: 0px;">&#160;</p><p>Maybe a better approach would be</p><p>1) to do the parameter checking in Javassist[Constructor/Method/Field]Info itself</p><p>2) to generate less classes? Something like:</p><p style="min-height: 8pt; height: 8pt; padding: 0px;">&#160;</p><pre class="jive-pre"><code class="jive-code jive-java"><font color="navy"><b>public</b></font> <font color="navy"><b>class</b></font> SomeBeanAccessor <font color="navy"><b>implements</b></font> JavassistBeanAccessor
<font color="navy">{</font>
&#160;&#160;&#160; <font color="navy"><b>public</b></font> Object newInstance(<font color="navy"><b>int</b></font> index, Object[] args) <font color="navy"><b>throws</b></font> Throwable
&#160;&#160;&#160; <font color="navy">{</font>
&#160;&#160;&#160;&#160;&#160;&#160; <font color="navy"><b>if</b></font> (index == 0)
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; <font color="navy"><b>return</b></font> <font color="navy"><b>new</b></font> SomeClass((String)args[0]);
&#160;&#160;&#160;&#160;&#160;&#160; <font color="navy"><b>else</b></font> <font color="navy"><b>if</b></font> (index == 1)
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; <font color="navy"><b>return</b></font> <font color="navy"><b>new</b></font> SomeClass((String)args[1]);
&#160;
&#160;&#160;&#160;&#160;&#160;&#160; <font color="navy"><b>return</b></font> <font color="navy"><b>null</b></font>;
&#160;&#160;&#160; <font color="navy">}</font>
&#160;
&#160;&#160;&#160; <font color="navy"><b>public</b></font> Object invoke(<font color="navy"><b>long</b></font> hash, Object target, Object[] args) <font color="navy"><b>throws</b></font> Throwable
&#160;&#160;&#160; <font color="navy">{</font>
&#160;&#160;&#160;&#160;&#160;&#160;&#160; <font color="navy"><b>if</b></font> (hash == 121267912)
&#160;&#160;&#160;&#160;&#160; <font color="navy"><b>return</b></font> ((SomeClass)target).someMethod(((Long)args[0]).longValue(), (String)args[1]);
&#160;&#160;&#160; <font color="navy"><b>if</b></font> (hash == 128172981)
&#160;
&#160;&#160;&#160;&#160;&#160; <font color="navy"><b>return</b></font> ((SomeClass)target).otherMethod(((Long)args[0]).longValue(), (String)args[1], (String)args[2]);
&#160;
&#160;&#160; <font color="navy">}</font>
&#160;
&#160;
&#160;
&#160;&#160; <font color="navy"><b>public</b></font> Object get(String name, Object target) <font color="navy"><b>throws</b></font> Throwable
&#160;
&#160;&#160; <font color="navy">{</font>
&#160;
&#160;&#160;&#160;&#160;&#160; <font color="navy"><b>if</b></font> (name.equals(<font color="red">"intField"</font>)
&#160;
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; <font color="navy"><b>return</b></font> Integer.valueOf(((SomeClass)target).intField);
&#160;
&#160;&#160;&#160;&#160;&#160; <font color="navy"><b>if</b></font> (name.equals(<font color="red">"stringField"</font>)
&#160;
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; <font color="navy"><b>return</b></font> ((SomeClass)target).stringField;
&#160;
&#160;&#160; <font color="navy">}</font>
&#160;
&#160;
&#160;
&#160;&#160; <font color="navy"><b>public</b></font> <font color="navy"><b>void</b></font> set(String name, Object target, Object value) <font color="navy"><b>throws</b></font> Throwable
&#160;
&#160;&#160; <font color="navy">{</font>
&#160;
&#160;&#160;&#160;&#160;&#160; <font color="navy"><b>if</b></font> (name.equals(<font color="red">"intField"</font>)
&#160;
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; ((SomeClass)target).intField = ((Integer)value).intValue();
&#160;
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; <font color="navy"><b>return</b></font>;
&#160;
&#160;&#160;&#160;&#160;&#160; <font color="navy"><b>if</b></font> (name.equals(<font color="red">"stringField"</font>)
&#160;
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; ((SomeClass)target).stringField = (String)value;
&#160;
&#160;&#160; <font color="navy">}</font>
&#160;
<font color="navy">}</font>
&#160;
</code></pre><p style="min-height: 8pt; height: 8pt; padding: 0px;">&#160;</p><p>First call by Javassist[Constructor/Method/Field]Info to access the member would result in this being created for ALL members, and cached in JavassistTypeInfo. </p></div>

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    <p style="margin: 0;">Reply to this message by <a href="http://community.jboss.org/message/537476#537476">going to Community</a></p>
        <p style="margin: 0;">Start a new discussion in JBoss Microcontainer Development at <a href="http://community.jboss.org/choose-container!input.jspa?contentType=1&containerType=14&container=2115">Community</a></p>
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