blocking at jbpmContext.getGraphSession()

[minghei]

Hello,

I am having some problem when running the following application in a multi-thread program

Working in single thread. everything can run smoothly. However, running in multi-thread I found that the thread always block at the line

graphSession = jbpmContext.getGraphSession();

How can I solve this ? Is there another way to implement it ?

thank you

public class Workflow {

    private static String configString = "";
    private static JbpmConfiguration jbpmConfiguration = null;

    static {
        try {
            configString = FileTools.readFileAsString("config\\jbpm.cfg.xml");
            jbpmConfiguration = JbpmConfiguration.parseXmlString(configString);
        } catch (Exception ex) {
            System.out.println("Error while loading configuration");
        }
    }

    public static void createInstance(String definitionName, String processID) throws Exception {
        JbpmContext jbpmContext = null;
        GraphSession graphSession = null;
        try {
            jbpmContext = jbpmConfiguration.createJbpmContext();
            graphSession = jbpmContext.getGraphSession();

            ProcessDefinition processDefinition = graphSession.findLatestProcessDefinition(definitionName);
            ProcessInstance processInstance =  new ProcessInstance(processDefinition);
            processInstance.setKey(processID);
            jbpmContext.save(processInstance);

        } catch (Exception ex) {
            ex.printStackTrace();
        } finally {
            jbpmContext.close();
        }
    }

}