my spreadsheet contains 3780 records. which create the same no of rules during runtime. the control just get hung in the line "knowledgeBase.addKnowledgePackages(knowledgeBuilder .getKnowledgePackages());" CODE SNIPPET ---------------------- public KnowledgeBase buildKnowledgeBaseFromSpreadsheet(String spreadSheet, String ruleTemplate, int rowNo, int colNo) { KnowledgeBuilder knowledgeBuilder = KnowledgeBuilderFactory .newKnowledgeBuilder(); KnowledgeBase knowledgeBase = KnowledgeBaseFactory.newKnowledgeBase(); String drl = externalSpreadsheetCompiler.compile(spreadSheetStream, ruleTemplateStream, 0, 0); knowledgeBuilder.add(new ByteArrayResource(drl.getBytes()), ResourceType.DRL); validateKnowledgeBuilder(knowledgeBuilder); // code which get hung *knowledgeBase.addKnowledgePackages(knowledgeBuilder .getKnowledgePackages());* return knowledgeBase; } public void validateKnowledgeBuilder(KnowledgeBuilder knowledgeBuilder) { if (knowledgeBuilder.hasErrors()) { System.out.println("Error compiling resources:"); for (KnowledgeBuilderError error : knowledgeBuilder.getErrors()) { System.err.println(error.toString()); } throw new IllegalStateException("Error compiling resources"); } } ----- Thanks... Himansu -- View this message in context: http://drools.46999.n3.nabble.com/knowledgeBase-addKnowledgePackages-api-... Sent from the Drools: User forum mailing list archive at Nabble.com.