Single Threaded Model JSP- Servlet

Servelts can be set to have thread safe access (Single thread model). However, when a JSP is converted in to a servlet, is the servlet tagged as to use the single thread model?

As of JSP specification 1.2 the default value for the "isThreadSafe" attribute of the page directive is true indicating that the container can direct multiple requests to the page simultaneously. If this value is set to false then the requests will be sent one at a time.
Good Luck!
Eshwar Rao
Developer Technical Support
Sun microsystems inc
http://www.sun.com/developers/support

Similar Messages

Using a single connection for jsp, servlets and classes

Hi! I'm building a web site that uses JSP, Servlets and some classes. I use database access in all my pages. I want to open a connection and use it for all the pages while the user is in my site, so I don't need to open a connection with every new jsp or servlet page. My software must be capable of connection with various databases, like SQLServer, Oracle, Informix, etc... so the solution must not be database (or OS or web server) dependant.
Can you help me with this? Some ideas, links, tips? I'll REALLY appreciate your help.
Regards,
Raul Medina

use an initialiation servlet with pooled connection which can be accessed as sesssion object.
Abrar

HttpService + Asynchronous + Single thread

I have a internal company Flex app similar to Jmeter. It generates HTTP requests and outputs based on asserts. The app uses Puremvc and leverages notifications to bring event-based asynchronous model. On a full-blown scan, I have two challenges:
1. To throttle requests so that the view is quick to appear (initially). A full blown scan generates 1040 requests, and the view doesn't appear for a few secs till all the requests are queued. Is there a way, I can force the view to come quickly before I complete the pushing of requests. I have implemented a throttle approach, but the results are not any better than no throttling.
2. I am forced to set httpservice.requestTimeout to 300 secs, as what I have found is that the thread eventually forces the timeout as due the single threading model, Flex hasn't been able to send the request through before a normal timeout of 15 secs is completed.
3. Is there a way to open more persistent connections to leverage, so that the performance of such bursts are improved?
Don't expect a reply, but any thoughts are welcome.....

Here is an ActionScript library that supposedly allows you to come closer to multi-threading:
http://code.google.com/p/async-threading/downloads/list
If you just want the UI to appear, have or generate minimal sample data, to be replaced as the data comes in. That way the UI can come up with reasonable minimum data for the UI.
Can the requests either be chunked into small pieces to facilitate quicker completion of requests, or else larger chunks to reduce the overall number of requests.
Can you compress the data and decompress after receipt to reduce the transfer load?
With your volume of requests it boils down to experimentation and consideration and what gives the best performance. I've never dealt with such issues, but thought I would share my ideas.

Xsql servlet threading model?

does anybody know the threading model supporting by the xsql servlet? from my testing, it appears that it only supports single threaded.
environment: nt 4.0, svcpack 5/iis/servlet exec 2.2/jdk 1.1.8/xsql servlet 0.9.6
any help/info appreciated.
thanks
michael lasmanis

steve,
here are the java vm settings from servlet exec. all the other settings are in line with the install instructions.
VM Settings
Java VM: 1.1.8 from Sun Microsystems Inc.
JITC: symcjit
Host: Windows NT 4.0 on x86
Native Stack Size: 128K Bytes
Java Stack Size: 400K Bytes
Minimum Heap Size: 1024K Bytes
Maximum Heap Size: 524288K Bytes
Verbose GC: Disabled
Verbose: Disabled
JITC: Enabled
Class GC: Enabled
Async GC: Enabled
Verify: Remote
Java VM: Sun Classic
null

Regarding single threaded servlet

why pool of instances for single threaded servlet?

why pool of instances for single threaded servlet
the container instantiates the servlet when it starts up or when the first request for that servlet comes, instantiation takes place only once.
when the request comes for a servlet, the container create a thread and gives it response and request object , when another request comes in it creates a thread and gives it request and response object, this process goeson..

Single threaded servlet

I need to connect to the database which has to handle multiple requests. So the best approach is to use single threaded servlet using pool of servlet instances.I read the document of single threaded servlet.I ahve gone through the code. here is the code given below:
import java.io.*;
import java.sql.*;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class SingleThreadConnection extends HttpServlet
implements SingleThreadModel {
Connection con = null; // database connection, one per pooled instance
public void init() throws ServletException {
// Establish the connection for this instance
try {
con = establishConnection();
con.setAutoCommit(false);
catch (SQLException e) {
throw new ServletException(e.getMessage());
public void doGet(HttpServletRequest req, HttpServletResponse res)
throws ServletException, IOException {
res.setContentType("text/plain");
PrintWriter out = res.getWriter();
try {
// Use the connection uniquely assigned to this instance
Statement stmt = con.createStatement();
// Update the database any number of ways
// Commit the transaction
con.commit();
catch (SQLException e) {
try { con.rollback(); } catch (SQLException ignored) { }
public void destroy() {
if (con != null) {
try { con.close(); } catch (SQLException ignored) { }
private Connection establishConnection() throws SQLException {
// Not implemented. See Chapter 9.
i need to know the code of establish connection. In my point of view,is it the database connection code or connection pool.But iam sure it cannot be connection pool.
Can you clear me with the code of how to establish the connection?
thanks in advance.

Preethi05 wrote:
private Connection establishConnection() throws SQLException {
// Not implemented. See Chapter 9.
i need to know the code of establish connection. In my point of view,is it the database connection code or connection pool.But iam sure it cannot be connection pool.
Can you clear me with the code of how to establish the connection?My guess is its the connection pool here, its a guess though. Also its mentioned there to see chapter 9, that might say something.
regards,'
a_joseph

I have a doubt about The Single-Thread Rule

The [url http://java.sun.com/docs/books/tutorial/uiswing/overview/threads.html#rule]Single Thread Rule states:
Rule: Once a Swing component has been realized, all code that might affect or depend on the state of that component should be executed in the event-dispatching thread.
I began to wonder about this because so much code seems to work just fine when it isn't executed in the event dispatching thread. Why are there exceptions? I went looking for some code which acted differently when executed on the event thread than when it was not. I found this
http://forum.java.sun.com/thread.jsp?forum=57&thread=410423&message=1803725#1803725
Now I started wondering why this was the case. What I found was that DefaultCaret adds a document listener to the document of the JTextComponent. In this listener, the insertUpdate() method specifically tests if it is running on the event dispatch thread and if it is, it updates the caret position.public void insertUpdate(DocumentEvent e) {
    if (async || SwingUtilities.isEventDispatchThread()) {
        // ... update the caret position ...
}I then copied the code from DefaultCaret and made a MyCaret. I needed to tweek the code a little bit, but it ran. I removed the event thread test. It worked outside the event thread. There was a small difference in the results though. The textarea did not scroll all the way to the bottom. Almost, but not quite. I didn't test enough to make sure this was the only problem, but there was at least one problem.
Now I started think about why this would be. The thought crossed my mind that the order of the events which were posted to the event queue were probably important. Sun found bugs when components were updated out of the event thread, so they essentially ignored events which weren't on the event thread and created the The Single-Thread Rule.
A few days pass. I'm starting to wonder if Sun could have done a better job making Swing components thread safe. I also don't know that this specific case I found was the rule or the exception to the rule. But without insight into the design philosopy of Swing, I would have to examine all their components and see how they have written them and see if I can come up with a better design. That sound like a lot of work. Especially without getting paid for it.
But wait a second, all you have to do is call the append() method of JTextArea on the event thread. If that is the case, why didn't they write the freakin component that way? Well, I'll try itclass MyTextArea extends JTextArea {
public MyTextArea(int rows, int columns) { super(rows,columns); }
public void append(final String text) {
    if (SwingUtilities.isEventDispatchThread()) super.append(text);
    else {
      SwingUtilities.invokeLater(new Runnable() {
        public void run() { myAppend(text); }
private void myAppend(String text) { super.append(text); }
}I change [url http://forum.java.sun.com/thread.jsp?forum=57&thread=410423&message=1803725#1803725]camickr's code to use a MyTextArea and it works fine without calling from the event thread. I've essentially moved The Single-Thread Rule to the component itself rather than relying on each and every one of the [url http://www.aboutlegacycoding.com/default.htm?AURL=%2FSurveys%2FSurvey6intro%2Easp]2.5 million Java programmers worldwide to use SwingUtilities.invaokeLater().
Now for my question...
Why didn't Sun do this?

Swing is slow enough as it is. Lets not make it slower
just
because dense "programmers" don't know what they are
doing.I agree with you in defending the current model, but aren't you a bit harsh there?!? ;-)
Well, there are a number of not-so-dense programmers that expect such high-level components to be thread-safe. The question is worth asking whether Sun intentionally favor the explicit thread management for performance reasons, or whether this was an oversight.
I'd go for the former (intentional) : indeed any GUI toolkit is inherently thread-based; there is always a distinction between the graphical thread(s) and the application threads - and the programmer always has to manage explicit thread creation to handle long-running event handlers without blocking the event dispatching thread. Extending thread concerns to the updating of components is therefore not a big move.
So it seems fair that a core GUI toolkit does not hide thread issues (though to the best of my knowledge there is no such limitation in updating AWT components), or at least that's what Sun deemed.
An ease-of-use-focused toolkit wrapping the core toolkit for thread-safety can be provided as a third-party product. Though I agree that wrapping the dozens of existing widgets and hundreds of methods is cumbersome - and the lack of such products probably shows it would have a low added value to trained developpers.
Because your way is an extra method call and if
statement, neither of which is necessary if you already know you
are in the correct thread. Now count the number of methods
which will need to be changed (and add up the extra cost).Indeed it's quite common to update several properties of several widgets in one bulk (when user clicks "OK", add a row to the table, change the title of the window, update status bar, re-enable all buttons, change some color,...).
In this case explicit thread management doesn't spare one if but a dozen of redundant ifs!
Note that there could have been if-less ways to cope for thread safety, such as creating a copy of the component's model when a change is made to a component, and switching the model only before paint() is called in the event-dispatching - of course coalescing all changes into the same "updated" model until paint() is called.
But this would trade ease of use for redundant memory consumption, especially for some components with potentially huge models (JTree, JTable, JTextArea,...). And Swing appears to be already quite memory-greedy!

Waiting for a mouse click in a single thread

Here's my problem:
I'm working on a program I didn't initially create, and I picked it up from the rough midpoint of its evolution. It is a single thread AWT program, with a mouseListener interface already implemented.
Here's my problem. In a game setting, we have two players. It is no problem when both are computer controlled. When player one is controlled by a human, I need to wait for a mouse event before returning, because upon returning player two moves (regardless of its player configuration).
I can't do any kind of busy waiting because it is a single thread. I'm looking for some kind of option besides making the program multithreaded. This also makes it difficult to use some sort of boolean variable, though I don't think it's impossible.
Thanks in advance for any help.
Eric

#9 - You are correct in your assumptions. I agree it's
not the best model, but it worked for the original
purpose, which was to have one player always
controlled by the computer, and the option of
selecting a second player as being either human or
computer. Since each move is made manually - that is,
for a move to be made, it requires user input - there
was no harm in returning from a function, because it
had no immediate computation. The requirements have
just changed, and now I must allow both players to be
selectable. This presents a problem in that I have to
wait for the move actions to finish before
proceeding.Understood.
>
My only question is, how can I access the AWT thread?You mentioned in an earlier post that you have action listeners. As triggered by user events, these are always called on the AWT thread. For example:
import javax.swing.*;
import javax.awt.event.*;
JButton button = new JButton( new AbstractAction {
        public void actionPerformed(ActionEvent e) {
            synchronized (myMonitor) {
                myMonitor.notifyAll();
    });This button can be added to some swing UI. If clicked on, then actionPerformed will be called on the AWT thread, and any threads waiting on myMonitor will be notified.
I see what you are saying - it's almost exactly what
my coworkers told me - but I don't have the knowledge
to implement it, which is why I'm here. Creating a
monitor object isn't a problem (makeMove() would need
to be synchronized, otherwise you wouldn't be able to
call wait()),I recommend using a separate object for the monitor, especially if you are already using synchronized, so that you know exactly how each object's lock is being used. If you're sure it is safe, then there is nothing wrong with using the object itself as the monitor, as you suggest, however.
but I'm not sure what you mean by the
action handling method should be called on the AWT
thread.Just that any action listener method is always called on the AWT thread in response to user action.
Dave

How to install eclipse and MyEclipse and use it for jsp-servlet-web service

hi ,
please help me to install eclipse 3.1 and How to integrate MyEclipse to do jsp-servlet programming and web services.
please also help me to include application server like tomcat and axis and use that environment in MyEclipse ide.
please help me.....

At the time of installation , you can't change SID XE.
After installation, you can add another service name
Check following thread for more details
Re: How to create service on Oracle 10g XE
- Virag Sharma
http://virag.sharma.googlepages.com
http://viragsharma.blogspot.com

Help! My application uses a Single Thread !

Hi all !
I have a web application which performs some long running tasks. This can be easily simulated with:
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
          System.out.println("Started Long Running Task!");
          try {
               Thread.sleep(20000);
          } catch (InterruptedException e) {
               e.printStackTrace();
          System.out.println("Done");
In order to deal with Long Running Tasks, I have created a WorkManager with MinThreads 10 and MaxThreads 100
Then I have assigned the Work Manager to the Web application usign weblogic.xml:
<?xml version="1.0" encoding="UTF-8"?>
<weblogic-web-app xmlns="http://www.bea.com/ns/weblogic/90">
<wl-dispatch-policy>WorkManager-0</wl-dispatch-policy>
</weblogic-web-app>
However it seems that the Web application uses a SINGLE Thread to reply to the Servlet. In other words issuing n parallel requests the output is:
Started Long Running Task!
[20 Seconds Pause]
Started Long Running Task!
[20 Seconds Pause]
Started Long Running Task!
[20 Seconds Pause]
Started Long Running Task!
[20 Seconds Pause]
My settings are the default Weblogic 12c Server settings, I've just added Weblogic NIO performance libs to the Java's path.
Is there any setting which allow just 1 Socket for my application ? Maybe it's because I'm using the "unlicensed" (free download) server version ?
Thanks a lot
Frank

You need to create separate Windows user accounts if you want to seperate the behaviour of iTunes for each user. That also means separate iTunes libraries for each user.
Windows is a multi-user operating system but you are not using it properly. iTunes is not a multi-user application. No application is. You can't expect it to treat different users differently when they are all using the same computer user account.
Do you understand what I mean?

Use of Synchronized in jsp/servlet

Can any one explain me the use of Synchronized in servlet/jsp which is multithreaded Is this correct synchronized should be used only when we want to pritect Static variable as they have only one copy but in case of instance variable they have seperate copy for each instance so no point of synchronized.
Thanks in advance

Hello again,
Take an external file for instance, you open a input stream to it and read data from it in your Java application. You can't have two threads reading at the same time, and one will likely block or throw an exception.
A better example is when your threads need to communicate with each other. If they all communicate via a set of variables that can be read and written to by any of them, then they should be synchronized. You should know if your threads need to communicate with each other? If they do not, there is no need for synchronisation.
What are your threads doing if you don't mind me asking?
I have to admit, I have had little experience using threads, and I have never needed to use threads in JSP (I don ot directly use servlets).
Regards,
Darren

Use of Threads with JSP's

Can you use threads in a web application that uses JSP's plus Servlets and Beans ?
We have a JRUN 3.1 application using JSPs, Servlets and Beans. Shortly after we went live it became apparent that any 2 users using the same object experienced problems as one object was overwriting another. In a panic the problem was solved by whacking SYNCHRONISED on all objects.
Now we want to write another application, are there strategies for using Threads with JSPs?
Would this be part of the webserver configuration or would the application be coded in a certain way ?
Please can you give me a simplistic answer or point me to some documentation that gives a simple overview.
Thanks Steve

Hi,
You can use thread with jsp, i am sending u a example
package thread;
import java.io.Serializable;
public class TaskBean implements Runnable, Serializable {
private int counter;
private int sum;
private boolean started;
private boolean running;
private int sleep;
public TaskBean() {
counter = 0;
sum = 0;
started = false;
running = false;
sleep = 100;
protected void work() {
try {
Thread.sleep(sleep);
counter++;
sum += counter;
} catch (InterruptedException e) {
setRunning(false);
public synchronized int getPercent() {
return counter;
public synchronized boolean isStarted() {
return started;
public synchronized boolean isCompleted() {
return counter == 100;
public synchronized boolean isRunning() {
return running;
public synchronized void setRunning(boolean running) {
this.running = running;
if (running)
started = true;
public synchronized Object getResult() {
if (isCompleted())
return new Integer(sum);
else
return null;
public void run() {
try {
setRunning(true);
while (isRunning() && !isCompleted())
work();
} finally {
setRunning(false);
And JSP page start.jsp
<% session.removeAttribute("task"); %>
<jsp:useBean id="task" scope="session"
class="thread.TaskBean"/>
<% task.setRunning(true); %>
<% new Thread(task).start(); %>
<jsp:forward page="status.jsp"/>
///////////////// status .jsp
<jsp:useBean id="task" scope="session"
class="thread.TaskBean"/>
<HTML>
<HEAD>
<TITLE>JSP Progress Bar</TITLE>
<% if (task.isRunning()) { %>
<SCRIPT LANGUAGE="JavaScript">
setTimeout("location='status.jsp'", 1000);
</SCRIPT>
<% } %>
</HEAD>
<BODY>
<H1 ALIGN="CENTER">JSP Progress Bar</H1>
<H2 ALIGN="CENTER">
Result: <%= task.getResult() %><BR>
<% int percent = task.getPercent(); %>
<%= percent %>%
</H2>
<TABLE WIDTH="60%" ALIGN="CENTER"
BORDER=1 CELLPADDING=0 CELLSPACING=2>
<TR>
<% for (int i = 10; i <= percent; i += 10) { %>
<TD WIDTH="10%" BGCOLOR="#000080"> </TD>
<% } %>
<% for (int i = 100; i > percent; i -= 10) { %>
<TD WIDTH="10%"> </TD>
<% } %>
</TR>
</TABLE>
<TABLE WIDTH="100%" BORDER=0 CELLPADDING=0 CELLSPACING=0>
<TR>
<TD ALIGN="CENTER">
<% if (task.isRunning()) { %>
Running
<% } else { %>
<% if (task.isCompleted()) { %>
Completed
<% } else if (!task.isStarted()) { %>
Not Started
<% } else { %>
Stopped
<% } %>
<% } %>
</TD>
</TR>
<TR>
<TD ALIGN="CENTER">
<BR>
<% if (task.isRunning()) { %>
<FORM METHOD="GET" ACTION="stop.jsp">
<INPUT TYPE="SUBMIT" VALUE="Stop">
</FORM>
<% } else { %>
<FORM METHOD="GET" ACTION="start.jsp">
<INPUT TYPE="SUBMIT" VALUE="Start">
</FORM>
<% } %>
</TD>
</TR>
</TABLE>
</BODY>
</HTML>
////////////////////////////// stop.jsp
<jsp:useBean id="task" scope="session"
class="thread.TaskBean"/>
<% task.setRunning(false); %>
<jsp:forward page="status.jsp"/>
deploy it into ur server and run start.jsp
and see whatb happens

JSP- Servlet-- Bean-- JSP how to implement

I have problem.
My JSP will take a emplyee id .
Now I want to show all the values regarding that employee in a JSP(JSP form) from the DB(Oracle).
So Iam planning like
JSP-->Servlet-->Bean-->JSP
So my doubts are.
1. Is it correct approach
2.If it is correct then which part of the flow connects to DB and stores the value before putting to JSP.
Iam using Tomcat 4.31
Plz help me

I have problem.
My JSP will take a emplyee id .
Now I want to show all the values regarding that
employee in a JSP(JSP form) from the DB(Oracle).
So Iam planning like
JSP-->Servlet-->Bean-->JSP
So my doubts are.
1. Is it correct approach
2.If it is correct then which part of the flow
connects to DB and stores the value before putting to
JSP.
Iam using Tomcat 4.31
Plz help meHI
What you are probably proposing is an MVC design pattern. I wonder if u have heard of the struts framework. Sruts uses MVC design pattern wherein the servlet u are talking about acts as a controller(C) and the bean acts as the model(M) .The JSPs present the view(V). Hence the name MVC.
Your approach is right. First get the employee ID from the jsp and get the corresponding data from database(This logic u implement in the servlet). Then save the fetched data in a bean so that the result jsp can fetch data from it.
Now this is not a strict MVC approach.
Learn more about struts. It presents a much more cleaner solution.

How to improve spreadsheet speed when single-threaded VBA is the bottleneck.

My brother works with massive Excel spreadsheets and needs to speed them up. Gigabytes in size and often with a million rows and many sheets within the workbook. He's already refined the sheets to take advantage of Excel's multi-thread recalculation and
seen significant improvements, but he's hit a stumbling block. He uses extensive VBA code to aid clarity, but the VB engine is single-threaded, and these relatively simple functions can be called millions of times. Some functions are trivial (e.g. conversion
functions) and just for clarity and easily unwound (at the expense of clarity), some could be unwound but that would make the spreadsheets much more complex, and others could not be unwound.
He's aware of http://www.analystcave.com/excel-vba-multithreading-tool/ and similar tools but they don't help as the granularity is insufficiently fine.
So what can he do? A search shows requests for multi-threaded VBA going back over a decade.
qts

Hi,
>> The VB engine is single-threaded, and these relatively simple functions can be called millions of times.
The Office Object Model is
Single-Threaded Apartments, if the performance bottleneck is the Excel Object Model operation, the multiple-thread will not improve the performance significantly.
>> How to improve spreadsheet speed when single-threaded VBA is the bottleneck.
The performance optimization should be based on the business. Since I’m not familiar with your business, so I can only give you some general suggestions from the technical perspective. According to your description, the size of the spreadsheet had reached
Gigabytes and data volume is about 1 million rows. If so, I will suggest you storing the data to SQL Server and then use the analysis tools (e.g. Power Pivot).
Create a memory-efficient Data Model using Excel 2013
and the Power Pivot add-in
As
ryguy72 suggested, you can also leverage some other third party data processing tool
according to your business requirement.
Regards,
Jeffrey
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Where can we tell OC4J to load multiple threads of a servlet?

I configured a web site on OC4J that uses a servlet. Everything is working fine.
Now, I want to start, lets say, 50 instances of this servlet when the web site
is started by OC4J. How can I do this? Which configuration files should
I play with? Please note that my servlet is single-threaded and that I want
all threads running in the same JVM.
I want to do something similar than this parameter in JServ:
singleThreadModelServlet.initialCapacity=100
Thanks

oc4j/orion is the fastest servlet engine on the planet. Those
guys in Sweden don't let you mess around with the number of
servlet instances available. The message here is that you do not
have to resort to any tricks that other servlet engines use to
make sure your servlet will be available to be served up...it
will.
The only thing that slows it down are lack of memory or lack of
resources (the database isn't replying fast enough). You can
solve these problems by clustering your servers on several
machines.
regards,
the elephantwalker
www.elephantwalker.com

Single Threaded Model JSP- Servlet

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