Bug 137176 It takes unacceptable long time to render a report
Description: Get the attached report design, preview in report designer. It takes unacceptable long time to render a report, and users could not get the output finally. Even during the rending, the computer could not do anything else.
viewer/org.eclipse.birt.report.viewer/birt/WEB-INF/classes/org/eclipse/birt/report/service/ReportEngineService.java
IGetParameterDefinitionTask task = null;
		try
		{
			synchronized ( this.getClass( ) )
			{
				task = engine.createGetParameterDefinitionTask( runnable );
			}
		}
		catch ( Exception e )
		{
		}
		return task;
	}
	/**
	 * Open report document from archive,
	 * 
	 * @param docName
	 *            the name of the report document
	 * @param systemId
	 *            the system ID to search the resource in the document,
	 *            generally it is the file name of the report design
	 * @return the report docuement
	 */
	public IReportDocument openReportDocument( String systemId, String docName )
	{
		IReportDocument document = null;
		try
		{
			synchronized ( this.getClass( ) )
			{