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<title>Using the classloader.properties file</title> |
<title>Using the Class Loader Properties File</title> |
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<h1>Using the classloader.properties file</h1> |
<h1>Using the Class Loader Properties File</h1> |
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Eclipse 2.0.2 includes many performance enhancements, including some in the area |
Eclipse 2.0.2 includes many performance enhancements, including some in the area |
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of classloading. In order to help out with this a classloader properties file |
of classloading. In order to help out with this a classloader properties file |
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was created and this file explains its use. |
was created and this file explains its use. |
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<p> |
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<h2>Activation</h2> |
<ul> |
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<li><a href="#activation">Activation</a></li> |
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<li><a href="#location">Location</a></li> |
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<li><a href="#format">Format</a></li> |
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<li><a href="#future">Future</a></li> |
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<li><a href="#trouble">Trouble-Shooting</a></li> |
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</ul> |
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<h2><a name="activation"></a>Activation</h2> |
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To enable the classloader performance enhancements, the user must pass the <code>-classloaderProperties</code> |
To enable the classloader performance enhancements, the user must pass the <code>-classloaderProperties</code> |
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command-line argument to the Eclipse executable. If the argument is used by itself |
command-line argument to the Eclipse executable. If the argument is used by itself |
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the default location (see below) is used for the classloader properties file. |
the default location (see below) is used for the classloader properties file. |
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file to use. |
file to use. |
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<h2>Location</h2> |
<h2><a name="location"></a>Location</h2> |
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The default location of the classloader properties file is as a sibling of the <code>boot.jar</code> |
The default location of the classloader properties file is as a sibling of the <code>boot.jar</code> |
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in the <code>org.eclipse.core.boot</code> plug-in. |
in the <code>org.eclipse.core.boot</code> plug-in. |
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For instance:<br> |
For instance:<br> |
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<code>/eclipse/plugins/org.eclipse.core.boot/classloader.properties</code> |
<code>/eclipse/plugins/org.eclipse.core.boot_2.0.2/classloader.properties</code> |
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<p> |
<p> |
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If the user specifies the location of the file, it can be either a path or a URL to a file. For instance:<br> |
If the user specifies the location of the file, it can be either a path or a URL to a file. For instance:<br> |
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</code> |
</code> |
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<p> |
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<h2>Format</h2> |
<h2><a name="format"></a>Format</h2> |
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The format of the classloader properties file is a <code>java.util.Properties</code> file. The key in the file is the name of the |
The format of the classloader properties file is a <code>java.util.Properties</code> |
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plug-in and the value is a comma-separated list of the package prefixes for the packages in the plug-in's jar. |
file. Each key in the file is the name of the plug-in and the value is a comma-separated |
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list of the package prefixes for the packages in the plug-in's jar. |
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<p> |
<p> |
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It is quite common for jar files to contain code which reside in multiple packages. For instance, the <code>runtime.jar</code> file |
It is quite common for jar files to contain code which reside in multiple packages. For instance, the |
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in the <code>org.eclipse.core.runtime</code> plug-in contains code in the following packages:<br> |
<code>org.eclipse.core.runtime</code> plug-in contains code in the following packages:<br> |
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<code> |
<code> |
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org.eclipse.core.runtime<br> |
org.eclipse.core.runtime<br> |
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org.eclipse.core.internal.runtime,<br> |
org.eclipse.core.internal.runtime,<br> |
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org.eclipse.core.internal.plugins<br> |
org.eclipse.core.internal.plugins<br> |
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org.eclipse.core.runtime.model</code>.<p> |
org.eclipse.core.runtime.model</code>. |
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In this case, in the classloader properties file we put specify the following line: |
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<p> |
<p> |
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In this case, the classloader properties specifies: |
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<code>org.eclipse.core.runtime=org.eclipse.core</code> |
<code>org.eclipse.core.runtime=org.eclipse.core</code> |
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<p> Notice that <code>org.eclipse.core</code> is a common prefix for all packages |
<p> Notice that <code>org.eclipse.core</code> is a common prefix for all packages |
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in the <code>runtime.jar</code>. The alternative is to declare all 4 prefixes |
in the plug-in. The alternative is to declare all 4 prefixes |
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in the file as a comma-separated list. In this case one must weigh the trade-off |
in the file as a comma-separated list. In this case one must weigh the trade-off |
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between the number of checks required against multiple entries and a prefix |
between the number of checks required against multiple entries and a prefix |
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which may include false hits. Depending on the way that your code is structured, |
which may include false hits. Depending on the way that your code is structured, |
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"com.mycompany" in the file. |
"com.mycompany" in the file. |
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<p> |
<p> |
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It is also common for plug-ins to contain multiple jar files with code. In this case all package prefixes from all jars |
When a plug-in contains multiple jar files with code, the entry in the the class loader |
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should appear in the classloader properties file. |
properties file should account for all package prefixes from all jars. |
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<p> |
<p> Note that missing a package prefix as a value entry in the file means that |
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your code will not work but not having an entry for your plug-in as a key in |
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Note that not having an entry for your plug-in as a key in the file doesn't mean that your code will not work, it just |
the file doesn't mean that your code will not work, it just means that you will |
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means that you will not be able to take advantage of classloading optimization. And note that missing a package |
not be able to take advantage of classloading optimization. |
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prefix as a value entry in the file does mean that your code will not work. |
<p>See the file which is shipped with Eclipse for an example. (<code>/eclipse/plugins/org.eclipse.core.boot_2.0.2/classloader.properties</code>) |
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See the file which is shipped with Eclipse for an example. |
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(<code>/eclipse/plugins/org.eclipse.core.boot/classloader.properties</code>) |
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<p> |
<p> |
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<h2>Future</h2> |
<h2><a name="future"></a>Future</h2> |
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As described above, currently one must add all package prefixes to the same properties |
As described above, currently one must add all package prefixes to the same properties |
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file. Future work in this area includes the ability to add mark-up to your <code>plugin.xml</code> |
file. Future work in this area includes the ability to add mark-up to your <code>plugin.xml</code> |
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file to take advantage of this classloading performance behaviour to make it easier |
file to take advantage of this classloading performance behavior to make it easier |
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for people who are extending the Eclipse platform. |
for people who are extending the Eclipse platform. |
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<p> |
<p> |
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<h2>Trouble-shooting</h2> |
<h2><a name="trouble"></a>Trouble-shooting</h2> |
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If you get a <code>java.lang.ClassNotFoundException</code> then that is an indication that there might be a problem |
If you get a <code>java.lang.ClassNotFoundException</code> then that is an indication that there might be a problem |
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with your entries in the properties file. The file could have the correct syntax, but the package prefixes in the |
with your entries in the properties file. The file could have the correct syntax, but the package prefixes in the |
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comma-separated list might be missing some entries. The workaround for this is to comment out the line of the offending plug-in. |
comma-separated list might be missing some entries. To verify this is the problem, use a number sign (#) to comment |
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out the line of the offending plug-in. |
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<p> |
<p> |
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</body> |
</body> |
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