Bug 88653 [Commands] performance: 50% of perspective switch in ParameterizedCommand.equals()
Build: I20050315 Setup: 1) Workspace with three projects, org.eclipse.jdt.core, org.eclipse.swt, and org.eclipse.swt.win32 2) Editor open on org.eclipse.jdt.internal.compiler.parser.Parser.java 3) Default Java perspective and Resource perspective open My test was to switch between the two open perspectives about five times using Ctrl+F8. The profiler showed 50% of the time in ParameterizedCommand.equals() and in the methods called by that equals implementation (Util.equals() and Command.equals()). The main problem is probably in the number of times this method is called (about 1.6 million times). This seems to be caused by a large number of property change events: ExternalActionManager$CommandCallback.bindingManagerChanged is called 30 times. This in turn calls ActionContributionItem$1.propertyChange, which is called 4787 times. The number of method calls explodes as you go down the call stack, until the equals method that is called 1.6 million times. I will attach profiler output to show more details. If the number of change events can't be reduced, it looks like the implementation of ParameterizedCommand.equals() can be made faster by first comparing the cached hash code. Only if the hash codes are the same does it need to do the remainder of the equality testing.
bundles/org.eclipse.core.commands/src/org/eclipse/core/commands/Command.java
* Returns the category for this command.
	 * 
	 * @return The category for this command; never <code>null</code>.
	 * @throws NotDefinedException
	 *             If the handle is not currently defined.
	 */
	public final Category getCategory() throws NotDefinedException {
		if (!isDefined()) {
			throw new NotDefinedException(
					"Cannot get the category from an undefined command"); 
		}
		return category;
	}
	/**
	 * Returns the parameters for this command. This call triggers provides a
	 * copy of the array, so excessive calls to this method should be avoided.
	 * 
	 * @return The parameters for this command. This value might be
	 *         <code>null</code>, if the command has no parameters.
	 * @throws NotDefinedException
	 *             If the handle is not currently defined.
	 */
	public final IParameter[] getParameters() throws NotDefinedException {
		if (!isDefined()) {
			throw new NotDefinedException(
					"Cannot get the parameters from an undefined command"); 
		}
		if ((parameters == null) || (parameters.length == 0)) {
			return null;
		}