tomcat singleThreadModel

public synchronized Servlet loadServlet() throws ServletException {

        if (unloading) {
            throw new ServletException(
                    sm.getString("standardWrapper.unloading", getName()));
        }

        // Nothing to do if we already have an instance or an instance pool
        if (!singleThreadModel && (instance != null))//这块代码可以看出如果singleThreadModel为false就返回以前创建的servlet实例

            return instance;

tomcat singleThreadModel

原文：http://blog.51cto.com/2839840/2048413