Using Berkeley XML DB in a servlet

Question

h2. Problem:
I have a servlet using Berkeley XML DB as listed in the code snippet below. For simplicity I have removed the exception handling from the code snippet. When I invoke the servlet several times, the memory usage goes high and gets released only when the application is undeployed i.e when the destroy() method is called.
h2. Questions:
1. Is this the best way to use Berkeley XML DB in a servlet?
2. What other techniques can be adopted to release memory held by XmlManager, XmlContainer and Environment?
Please help!
Thanks,
Madhav
h2. Code Snippet:
public class MyServlet extends HttpServlet {
String containerName = "mycontainer";
String content = "<hello>Hello World</hello>";
String environmentDir = ".";
XmlManager mgr = null;
XmlContainer cont = null;
Environment env = null;
public void init(ServletConfig config) throws ServletException {
EnvironmentConfig config = new EnvironmentConfig();
env = new Environment( new File(envHome), config);
XmlManagerConfig mconfig = new XmlManagerConfig();
mgr = new XmlManager(env, mconfig);
XmlContainerConfig cconfig = new XmlContainerConfig();
cont = mgr.createContainer(containerName, cconfig);
public void destroy() {
try {
if (cont != null)
cont.delete();
if (mgr != null)
mgr.delete();
if (env != null)
env.close();
} catch (Exception e) {
// ignore exceptions in cleanup
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException {
for (int i =; i < 5000; i++) {
XmlTransaction txn = mgr.createTransaction();
cont.putDocument(txn, newDocName, content);
txn.commit();
}

Answer 1

Hi,
I guess you posted not all code since I can't see for example configuring an environment for transaction support.
Is your servlet doing only what is described in the doGet() method?
Did you try to launch a stand-alone application and execute method doGet() multiple times? What happens with memory?
Maybe you are using in-memory logging?
Vyacheslav
UPD: Probably you don't want to create and commit a txn for every small document. Grouping some of documents in the scope of a single transaction might help. I'm not sure about memory, but in terms of efficiency it's faster
Edited by: detonator413 on Nov 13, 2009 11:38 PM
Edited by: detonator413 on Nov 14, 2009 12:38 AM