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From Regis <xu.re...@gmail.com>
Subject [classlib][performance] InitialContext searches for jndi.properties every contruction time(Harmony-4942)
Date Tue, 16 Oct 2007 07:58:59 GMT
Hi,
I survey the issue Harmony-4942, found the Harmony's behavior of finding 
"jndi.properties" file is not the same as ri's:
Harmony re-search the whole CLASSPATH every construction time, while ri 
just search once when using a classloader to
find the file at first time. The following code prove it:

=============begin=============

             URL url = new File("test1").toURL();
             URLClassLoader cltest1 = new URLClassLoader(new URL[] { url },
                     Thread.currentThread().getContextClassLoader());
             Thread test1 = new Thread(new Runnable() {

                 public void run() {
                     try {
                         System.out.println("test1 classloader"
                                 + Thread.currentThread()
                                         .getContextClassLoader());
                         FileOutputStream fos = new FileOutputStream(
                                 "test1/jndi.properties");
                         PrintStream ps = new PrintStream(fos);
                         ps
 
.println("java.naming.factory.initial=regis.jndi.MyDefaultInitialContextFactory");
 
ps.println("java.naming.provider.url=http://test1");
                         ps.close();

                         InitialContext context = new InitialContext();
                         System.out.println("test1.context=    " + context);
                         System.out.println("test1.context.env="
                                 + context.getEnvironment());

                         File file = new File("test1/jndi.properties");
                         file.delete();

                         // create new properties file with different values
                         fos = new FileOutputStream(
                                 "test1/jndi.properties");
                         ps = new PrintStream(fos);
                         ps
 
.println("java.naming.factory.initial=regis.jndi.MyDefaultInitialContextFactory");
 
ps.println("java.naming.provider.url=http://test1.new");
                         ps.close();

                         context = new InitialContext();
                         System.out.println("test1.new.context=" + context);
                         System.out.println("test1.new.context.env="
                                 + context.getEnvironment());

                     } catch (Exception e) {
                         e.printStackTrace();
                     }
                 }

             });
             // use different classloader
             test1.setContextClassLoader(cltest1);

             test1.start();

             url = new File("test2").toURL();
             URLClassLoader clSrc = new URLClassLoader(new URL[] { url 
}, Thread
                     .currentThread().getContextClassLoader());

             Thread test2 = new Thread(new Runnable() {

                 public void run() {
                     try {
                         System.out.println("test2 classloader"
                                 + Thread.currentThread()
                                         .getContextClassLoader());
                         FileOutputStream fos = new FileOutputStream(
                                 "test2/jndi.properties");
                         PrintStream ps = new PrintStream(fos);
                         ps
 
.println("java.naming.factory.initial=regis.jndi.MyDefaultInitialContextFactory");
 
ps.println("java.naming.provider.url=http://test2");
                         ps.close();
                         InitialContext context = new InitialContext();
                         System.out.println("test2.context=    " + context);
                         System.out.println("test2.context.env="
                                 + context.getEnvironment());
                     } catch (Exception e) {
                         e.printStackTrace();
                     }
                 }

             });

             // use different classloader
             test2.setContextClassLoader(clSrc);
             test2.start();

===================end=================
(I slightly modify MyDefaultInitialContextFactory, add environment 
values to MyInitialContext after initial)

the output is below, using jre1.6.0:

============start output===============

test1 classloaderjava.net.URLClassLoader@42e816
test1.context=    javax.naming.InitialContext@60aeb0
test1.context.env={java.naming.factory.initial=regis.jndi.MyDefaultInitialContextFactory,

java.naming.provider.url=http://test1}
test1.new.context=javax.naming.InitialContext@16caf43
test1.new.context.env={java.naming.factory.initial=regis.jndi.MyDefaultInitialContextFactory,

java.naming.provider.url=http://test1}
test2 classloaderjava.net.URLClassLoader@8813f2
test2.context=    javax.naming.InitialContext@1d58aae
test2.context.env={java.naming.factory.initial=regis.jndi.MyDefaultInitialContextFactory,

java.naming.provider.url=http://test2}

=============end output=================

So under same classloader, ri just search property file once.

In harmony we can use a map to hold property values for each classloader 
to avoid search at every construction time.
But i found Harmony is still slower than ri at first time to constuct 
InitialContext object, the most time is consumed at
org.apache.harmony.jndi.internal.EnvironmentReader line 233:
p.load(is);

Then i write some sample code to test performance of Properties.load():

Properties pro = new Properties();
          URL url = new
 
URL("jar:file:/home/bahamut/harmony/trunk/deploy/jdk/jre/lib/boot/jndi.jar!/jndi.properties");
          InputStream in = url.openStream();
          long start = System.currentTimeMillis();
          pro.load(in);
          long end = System.currentTimeMillis();
          System.out.println("time: " + (end - start));
          in.close();

          pro = new Properties();
          url = new
 
URL("jar:file:/home/bahamut/harmony/trunk/deploy/jdk/jre/lib/boot/jndi.jar!/jndi.properties");
          in = url.openStream();
          start = System.currentTimeMillis();
          pro.load(in);
          end = System.currentTimeMillis();
          System.out.println("time: " + (end - start));
          in.close();

output of ri:
time: 1
time: 0

output of harmony:
time: 231
time: 1

Harmony is slower than ri *two hundred* times!!
in above test, property file is in jndi.jar about 230k, if not in jar 
file, the time of harmony and ri are very close,
so i think there must be some problems of archive module. Is it because 
of we using different algorithm with ri,
or our implementation has bugs?

Best Regards,
Regis.

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