最近看到一个问题,所有200个Web容器线程都挂起了,这意味着没有任何服务可以为传入的请求提供服务,因此应用程序冻结了.
这是一个简单的Web应用程序和JMeter测试,我认为这证明了这个问题的原因.Web应用程序由两个类组成,即以下servlet:
public class SessionTestServlet extends HttpServlet {
protected static final String SESSION_KEY = "session_key";
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// set data on session so the listener is invoked
String sessionData = new String("Session data");
request.getSession().setAttribute(SESSION_KEY, sessionData);
PrintWriter writer = response.getWriter();
writer.println("<html><body>OK</body></html>");
writer.flush();
writer.close();
}
}
以及HttpSessionListener和HTTPSessionAttributeListener的以下实现:
public class SessionTestListener implements
HttpSessionListener, HttpSessionAttributeListener {
private static final ConcurrentMap<String, HttpSession> allSessions
= new ConcurrentHashMap<String, HttpSession>();
public void attributeRemoved(HttpSessionBindingEvent hsbe) {}
public void attributeAdded(HttpSessionBindingEvent hsbe) { …