sunilramu
asked on
how do i determine the session size in a j2ee application
hi experts,
we are trying to setup our application for performance testing up to 1700 concurrent users. system is using up all the jvm memory at a certain point and the session are not creted anymore after a certain number is reached. is there any way to find out what the session size is like for one user.
its a j2ee compliant web based application deployed on websphere 6.0
thanks
Sunil
we are trying to setup our application for performance testing up to 1700 concurrent users. system is using up all the jvm memory at a certain point and the session are not creted anymore after a certain number is reached. is there any way to find out what the session size is like for one user.
its a j2ee compliant web based application deployed on websphere 6.0
thanks
Sunil
ASKER
Repus024: thanks will try you code. In the mean time have you used javawebparts or has anyone used the session class in the javawebparts package.
I have never personally used the javawebparts package. Looking quickly at the JavaDocs it looks like the SessionSize object could be useful for what you need.
I would certainly try including it in your application for debugging purposes to see if it gives you what you are looking for.
The code I provided will provide a quick snapshot of the entire heap which obviously includes all sessions. If you need more detail from what my code or the SessionSize object provides, you can force a heap dump during the stress test and use heaproots to analyze it. This is a very useful application in determining the contents of the JVM heap.
http://www.alphaworks.ibm.com/tech/heaproots
I would certainly try including it in your application for debugging purposes to see if it gives you what you are looking for.
The code I provided will provide a quick snapshot of the entire heap which obviously includes all sessions. If you need more detail from what my code or the SessionSize object provides, you can force a heap dump during the stress test and use heaproots to analyze it. This is a very useful application in determining the contents of the JVM heap.
http://www.alphaworks.ibm.com/tech/heaproots
ASKER
i cant use SessionSize from javawebparts since not all objects in my session are serializable. And the code you gave is giving inconsistant results for 3-5 users. any idea how many users you would load it with to get consistent results.
Are your users actively doing work, or are they just logged onto the system. There is two types of memory issues:
1. Issues that arise from the session holding too many (large) objects. This will not allow garbage collection to be very effictive.
2. Issues arising from a spike in memory usage during a transaction. This is because too much transactional memory is being used, or objects are being referenced longer than they need to
The JSP page will help at identifying issues with #1. Issues with #2 will require the use of a profiler and some code analysis. What I've done in the past is log on several users. Do a few transactions with them (transactions you suspect are loading up the session). Then look at the page. Then log on one more user and do a few transactions. Then look at the page again.
If all of the users are actively doing work the transactional memory usage will produce inconsistent results. The JSP page is good for identifying classical memory leaks or heavyweight sessions as you can see the increase in memory usage over time or as users log on.
Please let me know if you still can't get consistent results from the JSP page.
1. Issues that arise from the session holding too many (large) objects. This will not allow garbage collection to be very effictive.
2. Issues arising from a spike in memory usage during a transaction. This is because too much transactional memory is being used, or objects are being referenced longer than they need to
The JSP page will help at identifying issues with #1. Issues with #2 will require the use of a profiler and some code analysis. What I've done in the past is log on several users. Do a few transactions with them (transactions you suspect are loading up the session). Then look at the page. Then log on one more user and do a few transactions. Then look at the page again.
If all of the users are actively doing work the transactional memory usage will produce inconsistent results. The JSP page is good for identifying classical memory leaks or heavyweight sessions as you can see the increase in memory usage over time or as users log on.
Please let me know if you still can't get consistent results from the JSP page.
To find out what the session sizes for each web application use the tool "probe"
It's installed as a war to your application server
Get it from www.lambdaprobe.org/
It also gives real time graphs of memory usage.
It's a good tool to have in your development collection anyway
It's installed as a war to your application server
Get it from www.lambdaprobe.org/
It also gives real time graphs of memory usage.
It's a good tool to have in your development collection anyway
sorry, just read that your using websphere 6.0 probe only works with tomcat
ASKER
Following code does the job. i got if from one of the websphere appserver performance tuning articles.
Also you have an option of monitoring session management in webspehere tivoli PMI.
thanks all.
Also you have an option of monitoring session management in webspehere tivoli PMI.
thanks all.
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<HTML>
<HEAD>
<%@ page
language="java"
contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"
%>
<META http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<META name="GENERATOR" content="IBM WebSphere Studio">
<TITLE>SessionObjects.jsp</TITLE>
</HEAD>
<BODY>
<H1>Session Object List JSP</H1>
This JSP will dump information about the current HTTPSession.<br><br>
<%@ page import="java.io.*,java.util.*,javax.servlet.*" session="false" %>
<%! public void dumpSession(HttpServletRequest request, JspWriter out) throws IOException {
HttpSession session = request.getSession(false);
Object ro = null ;
out.println("Session ID from session.getID : "
+ session.getId() + "<br>");
out.println("Session ID from getHeader: "
+ request.getHeader("Cookie") + "<br>");
Enumeration enum = session.getAttributeNames();
if ( enum.hasMoreElements() )
{
int totalSize = 0;
out.println("<h3>Session Objects:</h3>");
out.println("<TABLE Border=\"2\" WIDTH=\"65%\" BGCOLOR=\"#DDDDFF\">");
out.println("<tr><th>Name</th>");//<th>Object.toString()</th>");
out.println("<th>Raw Bytes</th><th>Size (bytes)</th></tr>");
while ( enum.hasMoreElements() )
{
String name = (String)enum.nextElement();
Object sesobj = session.getAttribute(name) ;
ObjectOutputStream oos = null;
ByteArrayOutputStream bstream = new ByteArrayOutputStream();
try {
oos = new ObjectOutputStream(bstream);
oos.writeObject(sesobj);
}
catch (Exception e) {
e.printStackTrace();
}
finally {
if (oos != null) {
try {oos.flush();}
catch (IOException ioe) {}
try {oos.close();}
catch (IOException ioe) {}
}
}
ObjectInputStream ois = null;
ro = null ;
try {
ois = new ObjectInputStream(new ByteArrayInputStream(bstream.toByteArray()));
ro = ois.readObject();
}
catch (Exception e) {
e.printStackTrace();
}
finally {
if (ois != null) {
try {ois.close();}
catch (IOException ioe) {}
}
}
totalSize += bstream.size();
out.println("<tr>");
out.println("<td>" + name + "</td>");
// out.println("<td>" + session.getAttribute(name) + "</td>");
out.println("<td>" + ro + "</td>");
out.println("<td>" + bstream.size() + " bytes </td></tr>");
}
out.println("</table>");
out.println("Total Bytes: " + totalSize + "<br><br>");
} else {
out.println("No objects in session");
}
}
%>
<%
response.setHeader("Pragma", "No-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires",0);
HttpSession session = request.getSession(false);
if (session == null) {
out.println("No session");
} else {
dumpSession(request, out);
}
%>
</BODY>
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I've heard that JProfiler is much better, although it comes with a price tag:
http://www.ej-technologies.com/products/jprofiler/overview.html
I used a simple JSP page before to monitor the memory stats for the application as a whole. This is not session level information but what you could do is run your application, view this jsp page, log on another user, and then view the jsp page again. The increase would be the memory being held by that user's session that can't be freed. Please see the attached code snippet for the JSP code.
Please let me know if you have any questions or trouble with these resources.
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