Eclipse 2.0.2 includes many performance enhancements, including some in the area of classloading. In order to help out with this a classloader properties file was created and this file explains its use.
-classloaderPropertiescommand-line argument to the Eclipse executable. If the argument is used by itself the default location (see below) is used for the classloader properties file. Alternatively the argument can be followed by a path or URL to the appropriate file to use.
org.eclipse.core.bootplug-in. For instance:
If the user specifies the location of the file, it can be either a path or a URL to a file. For instance:
It is important to note that the file which is used by the system (either the default or the one which is specified by the user) is exclusive and does not represent the intersection between multiple files. That being said, if the user specifies a particular file to use, then the contents of the default file must be merged with it in order for the class loader enhancements to take effect for the classes in the Eclipse Platform; the contents of the default file are not automatically used.
java.util.Propertiesfile. Each key in the file is the name of the plug-in and the value is a comma-separated list of the package prefixes for the packages in the plug-in's jar.
It is quite common for jar files to contain code which reside in multiple packages. For instance, the
org.eclipse.core.runtime plug-in contains code in the following packages:
In this case, the classloader properties specifies:
org.eclipse.core is a common prefix for all packages
in the plug-in. The alternative is to declare all 4 prefixes
in the file as a comma-separated list. In this case one must weigh the trade-off
between the number of checks required against multiple entries and a prefix
which may include false hits. Depending on the way that your code is structured,
it might be best to list as many as 5-10 package prefixes rather than going
with a more general prefix. For instance, if all your code across multiple plug-ins
contains the same prefix (e.g.
com.mycompany) then you will not
be taking full advantage of all benefits if you list only the single prefix
"com.mycompany" in the file.
When a plug-in contains multiple jar files with code, the entry in the class loader properties file should account for all package prefixes from all jars.
Note that missing a package prefix as a value entry in the file means that your code will not work but 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 means that you will not be able to take advantage of classloading optimization.
See the file which is shipped with Eclipse for an example. (
plugin.xmlfile to take advantage of this classloading performance behavior to make it easier for people who are extending the Eclipse platform.
java.lang.ClassNotFoundExceptionthen that is an indication that there might be a problem with your entries in the properties file. The file could have the correct syntax, but the package prefixes in the comma-separated list might be missing some entries. To verify this is the problem, use a number sign (#) to comment out the line of the offending plug-in.
classloader.propertiesfile which ships with Eclipse 2.0.2.
org.apache.ant = org.apache.tools
org.apache.lucene = org.apache.lucene
org.apache.xerces = org.apache, org.w3c.dom, org.xml.sax, javax.xml
org.eclipse.ant.core = org.eclipse.ant
org.eclipse.compare = org.eclipse.compare
org.eclipse.core.resources = org.eclipse.core
org.eclipse.core.runtime = org.eclipse.core
org.eclipse.debug.core = org.eclipse.debug.core, org.eclipse.debug.internal.core
org.eclipse.debug.ui = org.eclipse.debug.ui, org.eclipse.debug.internal.ui
org.eclipse.help = org.eclipse.help
org.eclipse.help.ui = org.eclipse.help.ui
org.eclipse.jdt.core = org.eclipse.jdt.core, org.eclipse.jdt.internal
org.eclipse.jdt.debug = com.sun.jdi, org.eclipse.jdi, org.eclipse.jdt
org.eclipse.jdt.debug.ui = org.eclipse.jdt.debug.ui, org.eclipse.jdt.internal.debug.ui
org.eclipse.jdt.junit = org.eclipse.jdt.internal.junit
org.eclipse.jdt.launching = org.eclipse.jdt.launching, org.eclipse.jdt.internal.launching
org.eclipse.jdt.ui = org.eclipse.jdt.internal, org.eclipse.jdt.ui
org.eclipse.pde.build = org.eclipse.pde.internal.build
org.eclipse.pde.core = org.eclipse.pde.core, org.eclipse.pde.internal.core
org.eclipse.pde.runtime = org.eclipse.pde.internal.runtime
org.eclipse.pde.ui = org.eclipse.pde.ui, org.eclipse.pde.internal.ui
org.eclipse.search = org.eclipse.search
org.eclipse.swt = org.eclipse.swt
org.eclipse.team.core = org.eclipse.team.core, org.eclipse.team.internal.core
org.eclipse.team.cvs.core = org.eclipse.team.internal.ccvs.core
org.eclipse.team.cvs.ssh = org.eclipse.team.internal.ccvs.ssh
org.eclipse.team.cvs.ui = org.eclipse.team.internal.ccvs.ui
org.eclipse.team.ui = org.eclipse.team.ui, org.eclipse.team.internal.ui
org.eclipse.ui = org.eclipse.ui, org.eclipse.jface
org.eclipse.ui.externaltools = org.eclipse.ui.externaltools
org.eclipse.update.core = org.eclipse.update
org.eclipse.update.ui = org.eclipse.update.internal.ui
org.eclipse.update.forms = org.eclipse.update.ui.forms
org.junit = junit