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From Jeffrey E Care <ca...@us.ibm.com>
Subject RE: class loading speed can be improved in AntClassLoader.java
Date Wed, 25 Apr 2007 22:43:40 GMT
It may be better to open a feature request in bugzilla and attach the 
patch there.

____________________________________________________________________________________________


Jeffrey E. (Jeff) Care 
carej@us.ibm.com 
IBM WebSphere Application Server 
Systems Management Tools Architecture & Development 







"Brus, Tom" <Tom.Brus@nl.compuware.com> 
04/25/2007 01:29 PM
Please respond to
"Ant Developers List" <dev@ant.apache.org>


To
"Ant Developers List" <dev@ant.apache.org>
cc

Subject
RE: class loading speed can be improved in AntClassLoader.java






> From: Peter Reilly [mailto:peter.kitt.reilly@gmail.com]
> Sent: Wednesday, April 25, 2007 15:24
>
> This sounds useful,
> can you provide a patch please?

With pleasure (also attached in case there are line wrapping problems):

========= snip snip ===========
diff -Naur old/org/apache/tools/ant/AntClassLoader.java
new/org/apache/tools/ant/AntClassLoader.java
--- old/org/apache/tools/ant/AntClassLoader.java        2006-12-13
06:16:00.000000000 +0100
+++ new/org/apache/tools/ant/AntClassLoader.java        2007-04-25
19:17:46.546875000 +0200
@@ -799,19 +799,16 @@
      */
     private InputStream getResourceStream(File file, String
resourceName) {
         try {
-            if (!file.exists()) {
-                return null;
-            }
-
-            if (file.isDirectory()) {
+            // is it a file in the zipfile cache
+            ZipFile zipFile = (ZipFile) zipFiles.get(file);
+            if (zipFile==null && file.isDirectory()) {
+                // not in the cache, but it is a dir
                 File resource = new File(file, resourceName);
-
                 if (resource.exists()) {
                     return new FileInputStream(resource);
                 }
-            } else {
-                // is the zip file in the cache
-                ZipFile zipFile = (ZipFile) zipFiles.get(file);
+            } else if (zipFile!=null || file.exists()) {
+                // found in the cache or not yet in the cache but
existing
                 if (zipFile == null) {
                     zipFile = new ZipFile(file);
                     zipFiles.put(file, zipFile);
@@ -994,13 +991,11 @@
      */
     protected URL getResourceURL(File file, String resourceName) {
         try {
-            if (!file.exists()) {
-                return null;
-            }
-
-            if (file.isDirectory()) {
+            // is it a file in the zipfile cache
+            ZipFile zipFile = (ZipFile) zipFiles.get(file);
+            if (zipFile==null && file.isDirectory()) {
+                // not in the cache, but it is a dir
                 File resource = new File(file, resourceName);
-
                 if (resource.exists()) {
                     try {
                         return FILE_UTILS.getFileURL(resource);
@@ -1008,13 +1003,12 @@
                         return null;
                     }
                 }
-            } else {
-                ZipFile zipFile = (ZipFile) zipFiles.get(file);
+            } else if (zipFile!=null || file.exists()) {
+                // found in the cache or not yet in the cache but
existing
                 if (zipFile == null) {
                     zipFile = new ZipFile(file);
                     zipFiles.put(file, zipFile);
                 }
-
                 ZipEntry entry = zipFile.getEntry(resourceName);
                 if (entry != null) {
                     try {
========= snip snip ===========
> Hi,
>
> We have a lot of classes that are loaded by the AntClassLoader. From
> performance measurements I noticed that a lot of time was spend in
> File.exists() during class loading. I checked the code and noticed
that
> in:
>
>      InputStream getResourceStream  (File file, String resourceName);
>
> and in
>
>      URL         getResourceURL     (File file, String resourceName);
>
> The following check is done first:
>
>      if (!file.exists()) {
>          return null;
>      }
>
> This seems smart, because if the file does not exist the answer is
> clear. Unless of course 'exists()' is slow; which it turns out to be
(on
> Windows at least). A considerable improvement can be accomplished by
> first checking the 'zipFiles' Hashtable: if "zipFiles.get(file)"
returns
> non-null we can be sure that the file exists and that it is not a
> directory. Remember that most calls will be for a jar file that has
> already been opened. So those expensive (compared to Hashtable.get())
> tests on File can be skipped most of the time.
>
> One of our test runs was reduced by 1/3 in runtime by a quick patch I
> made (it loads thousands of classes...).
>
> Has this issue ever been noticed/discussed?
>
> Regards,
> Tom Brus
>
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contains information that may be confidential. Unless you are the named 
addressee or an authorized designee, you may not copy or use it, or 
disclose it to anyone else. If you received it in error please notify us 
immediately and then destroy it.

Compuware Europe B.V. (Registration number: 33245192) is a company 
registered in The Netherlands whose registered office is at  Hoogoorddreef 
5, 1101 BA  Amsterdam, The Netherlands. Compuware B.V. (Registration 
number: 33227492) is a company registered in the Netherlands whose 
registered office is at Hoogoorddreef 5, 1101 BA  Amsterdam, The 
Netherlands
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