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From Stephen Colebourne <scolebou...@btopenworld.com>
Subject Re: Can we optimize HashCodeBuilder.append(Object)?
Date Mon, 02 Jul 2007 09:49:19 GMT
Hi,
Have you got figures to show what difference the code change makes?

If so, perhaps you could raise a JIRA call so we can process this for 
[lang].

thanks
Stephen

Venkatesh Prasad Ranganath wrote:
> Hi,
> 
> I am using HashCodeBuilder and I found that the use of Class.isArray()
> method in append(Object) to be a bottleneck.  Following program and
> jprof data illustrates the bottleneck along with a solution.  I was
> curious if we can integrate the solution code in
> OptimizedHashCodeBuilder.append(Object) into
> HashCodeBuilder.append(Object) in the upcoming version 2.3 release of
> Commons Lang.
> 
> CPU SAMPLES BEGIN (total = 71) Sat Jun 30 16:51:43 2007
> rank   self  accum   count trace method
>    1 45.07% 45.07%      32 300138 java.lang.Class.isArray
>    2 14.08% 59.15%      10 300141 java.util.AbstractList.hashCode
>    3 12.68% 71.83%       9 300142 java.util.AbstractList.hashCode
>    4  4.23% 76.06%       3 300030
> sun.nio.cs.UTF_8$Decoder.decodeArrayLoop   5  4.23% 80.28%       3
> 300144 java.util.AbstractList.hashCode
>    6  2.82% 83.10%       2 300143 Test.run2
>    7  2.82% 85.92%       2 300139 java.util.ArrayList.get
>    8  1.41% 87.32%       1 300140 java.util.AbstractList.hashCode
>    9  1.41% 88.73%       1 300145 java.util.AbstractList.hashCode
>   10  1.41% 90.14%       1 300027 sun.nio.cs.UTF_8$Decoder.<init>
>   11  1.41% 91.55%       1 300012 java.nio.DirectByteBuffer.<init>
>   12  1.41% 92.96%       1 300089 sun.security.provider.Sun.<clinit>
>   13  1.41% 94.37%       1 300132 sun.security.provider.Sun.<init>
>   14  1.41% 95.77%       1 300071 java.lang.StringCoding.decode
>   15  1.41% 97.18%       1 300031
> sun.reflect.NativeConstructorAccessorImpl.newInstance  16  1.41%
> 98.59%       1 300048 java.net.URLClassLoader.defineClass
>   17  1.41% 100.00%       1 300137
> sun.net.www.ParseUtil.canonizeStringCPU SAMPLES END
> 
> 
> import org.apache.commons.lang.builder.HashCodeBuilder;
> 
> public class Test {
> 
>   public static void main(String[] s) {
>     java.util.ArrayList o = new java.util.ArrayList();
>     o.add("Hello");
>     o.add("World");
>     run1(o);
>     run2(o);
>   }
> 
>   static void run1(Object o) {
>     for (int i = 0; i < 10000; i++) {
>       HashCodeBuilder h = new HashCodeBuilder();
>       for (int k = 0; k < 100; k++) {
>         h = h.append(o);
>       }
>     }
>   }
> 
>   static void run2(Object o) {
>     for (int i = 0; i < 10000; i++) {
>       HashCodeBuilder h = new OptimizedHashCodeBuilder();
>       for (int k = 0; k < 100; k++) {
>         h = h.append(o);
>       }
>     }
>   }
> }
> 
> class OptimizedHashCodeBuilder extends HashCodeBuilder {
>         public HashCodeBuilder append(final Object object) {
>                 if (object == null) {
>                         super.append(object);
> 
>                 } else {
>                         // 'Switch' on type of array, to dispatch to
> the correct handler                        // This handles multi
> dimensional arrays
>                         if (object instanceof long[]) {
>                                 append((long[]) object);
>                         } else if (object instanceof int[]) {
>                                 append((int[]) object);
>                         } else if (object instanceof short[]) {
>                                 append((short[]) object);
>                         } else if (object instanceof char[]) {
>                                 append((char[]) object);
>                         } else if (object instanceof byte[]) {
>                                 append((byte[]) object);
>                         } else if (object instanceof double[]) {
>                                 append((double[]) object);
>                         } else if (object instanceof float[]) {
>                                 append((float[]) object);
>                         } else if (object instanceof boolean[]) {
>                                 append((boolean[]) object);
>                         } else if (object instanceof Object[]) {
>                                 // Not an array of primitives
>                                 append((Object[]) object);
>                         } else {
>                                 // the simple case, not an array, just
> the element                                append(object.hashCode());
>                         }
>                 }
>                 return this;
>         }
> }
> 
> ====
> 
> Venkatesh Prasad Ranganath
> e-id: venkateshprasad.ranganath@gmail.com
> e-id: rvprasad@ksu.edu
> web: http://www.cis.ksu.edu/~rvprasad
> blog: http://venkateshthinks.blogspot.com
> 
> 
> 
> 
> 

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