Weblogic Authors: Yeshim Deniz, Elizabeth White, Michael Meiner, Michael Bushong, Avi Rosenthal

Related Topics: Weblogic

Weblogic: Article

HTTP Session Object vs Stateful EJB

HTTP Session Object vs Stateful EJB

One of the big controversies of session handling concerns the performance difference between storing session state in an HTTP session object and using a stateful session bean. My colleagues and I expected that it would be more efficient to store data in an HTTP session object, as we were under the impression that there is more overhead involved with the infrastructure of session beans in the EJB container. Therefore, we were interested in measuring the performance of each method, to prove or disprove our initial notion.

To test this out, we created a small application that we used to store a specified amount of randomly generated content in either an HTTP session object or in a stateful session bean (size=number_of_bytes_to_store). Our application consisted of a single class, the SessionServlet, which we used both as a servlet and as a session listener. The servlet methods were responsible for handling requests and storing data in the associated session, using a specified storage method. When the servlet was requested using the argument type=0, it stored data in an HttpSession object, but when run with the argument type=1, it stored the data in a stateful session bean. When we used the session bean, we still needed the HTTP session object to store the bean's handle, in order to associate the bean instance with the client.

In addition to being a servlet, the SessionServlet extended the HttpSessionListener interface. We did this to ensure that all session beans would be removed from the container when the associated session was invalidated. If we had not explicitly removed the session beans - by calling the ejbRemove() method, as you will see later - they would have been passivated by the bean container, resulting in a dramatic impact on performance.

The test environment was based on the WebLogic server 6.1 SP2 running out of the box (15 execute threads). We used JDK 1.3.1-b24 HotSpot Server and the only parameter we defined was the heap space of 128MB (-ms and -mx were the same). The computer was a Sun Ultra 60 with dual Ultra SPARC II 450MHz, 512MB of memory, running Solaris 2.7. All of the tests were conducted on a dedicated 100Mbps network in which the only traffic present was generated by the tests themselves.

Once the SessionServlet had been deployed, we used The Grinder (http://grinder.sourceforge.net) to generate a test load in which each simulated user executed a test script (see Listing 1). As you can see, every request stores a different amount of bytes. The total number of bytes stored per session is 3,200. Also note that there is no think time between requests. We did this deliberately to maximize the stress on the system.

To make sure that the stateful beans were removed at the end of every HTTP session, we set the HTTP session timeouts in the WebLogic server to 5 seconds and forced the test script to sleep for 6 seconds before starting a new HTTP session.

We ran the tests using 100, 200, 300, 400, and 500 simultaneous active users, each executing the test script in a sequential fashion for the duration of the test runs. The sample size was 10 minutes after ignoring the first 3 minutes of execution of the test. The results for the average response time can be seen in Figure 1.

The figure presents the aggregate average response time, which is the average of all the individual average response times for each of the 10 requests that make up the test script. We also present the average response time for the first request, which we expect to be a little more expensive than the other requests since this one has to establish the HTTP connection and create the HTTP session object (as well as the stateful session bean when type=1).

Notice how the first request becomes less expensive than the aggregate value of the response time as the load increases. This shows that under high loads the manipulation of the HTTP session object is more expensive than the HTTP handshake and the creation of the HTTP session object.

Looking at Figure 2, the total transactional rate, we notice that we have not yet reached the full capacity of the application server, as the curve has not stabilized.

The network utilization varied from an average of less than 1% for the case of 100 users all the way up to about 4% for 500 users (see Figure 3).

A similar occurrence was observed with the CPU usage of the computer running the application, which varied from an average of 20% for 100 users to about 90% for 500 users (see Figure 4).

The next set of tests uses the stateful session bean by specifying type=1 as an argument to the servlet. To our amazement, the results were basically the same as the comparison seen in Figure 5.

In the case of the transactional rate, the biggest difference was on the order of 1%, which can be considered negligible. We did observe that the network and CPU utilization of this set of tests was basically the same as the ones for the tests using the HTTP session object.

We had to acknowledge that the stateful session bean did not use the security features offered by the EJB container. Nevertheless, it was interesting to find out that under the test conditions the comparative costs of storing data in an HTTP session object are roughly the same as storing the same data in a stateful session bean. To say the very least, this came as a surprise.

I strongly encourage you to test your situation, taking particular care of the think times you use in the test scripts. Although I'm sure you'll see different raw performance numbers, I expect that the comparative costs between the two models will be roughly the same.

The think times can have a very big impact on the results you obtain. We did not use think times purposely to observe behavior in a high-stress situation. You must use the real think times that apply to the normal utilization of your application.

Using ejbRemove
One of the most common programming mistakes in J2EE is to forget to explicitly destroy or remove EJBs once they have been used. This usually happens when you call EJBs from servlets. We mentioned earlier that we took a lot of care in our previous tests to make sure that the EJBs were removed. We did this by implementing a session listener, which made sure that before a session was terminated, all the beans it may have been using would be terminated. In addition, we made sure that our test script waited until the HTTP session timed out, giving the listener time to remove the EJBs.

Failure to remove an EJB that should have been removed carries a very high price from the performance perspective. Basically, what happens is that the EJB will be passivated, a rather silly way of removing an EJB from the container. As you probably know, passivation is a very expensive operation, as it first serializes the bean, and then writes it to disk.

To clearly illustrate the expense of passivation, we modified the servlet used for the previous tests. We did this by adding a type=2 test that will not remove the stateful session bean when the HTTP session is terminated. The differences in performance are so big we had to use a logarithmic scale for the chart in Figure 6. The picture for the transactional rate is even worse (see Figure 7).

If we remove the EJB while the number of users increases, the throughput also increases; if we don't remove it, the throughput actually decreases as the number is users increases.

It's amazing to find out that the cost of storing data in an HTTP session object is basically the same as using a stateful session bean, assuming the bean is removed in a proper way at the time the session terminates. Not doing so will have a negative impact on the performance of the application. But knowing that the beans must be removed is one thing - actually getting it done in time is another. In fact, it takes a considerable programming effort to ensure that this is done correctly. In our case, we used the session listener mechanism to monitor the session lifecycle and then to cut in moments before the beans are passivated. For your own applications, you can use this method or any other you find more viable. In any case, always make sure to properly test and analyze the system before making any final decisions.

This article is an extract from the book J2EE Performance Testing by Peter Zadrozny (Expert Press, June 2002). Special thanks to Bjarki Hólm and Gareth Chapman for their help in preparing the application used for these tests.

More Stories By Peter Zadrozny

Peter Zadrozny is CTO of StrongMail Systems, a leader in digital messaging infrastructure. Before joining StrongMail he was vice president and chief evangelist for Oracle Application Server and prior to joining Oracle, he served as chief technologist of BEA Systems for Europe, Middle East and Africa.

Comments (1) View Comments

Share your thoughts on this story.

Add your comment
You must be signed in to add a comment. Sign-in | Register

In accordance with our Comment Policy, we encourage comments that are on topic, relevant and to-the-point. We will remove comments that include profanity, personal attacks, racial slurs, threats of violence, or other inappropriate material that violates our Terms and Conditions, and will block users who make repeated violations. We ask all readers to expect diversity of opinion and to treat one another with dignity and respect.

Most Recent Comments
Dave Whaley 02/03/03 08:05:00 PM EST

A very useful subject -- applies to our current application

@ThingsExpo Stories
In his session at 21st Cloud Expo, Carl J. Levine, Senior Technical Evangelist for NS1, will objectively discuss how DNS is used to solve Digital Transformation challenges in large SaaS applications, CDNs, AdTech platforms, and other demanding use cases. Carl J. Levine is the Senior Technical Evangelist for NS1. A veteran of the Internet Infrastructure space, he has over a decade of experience with startups, networking protocols and Internet infrastructure, combined with the unique ability to it...
"There's plenty of bandwidth out there but it's never in the right place. So what Cedexis does is uses data to work out the best pathways to get data from the origin to the person who wants to get it," explained Simon Jones, Evangelist and Head of Marketing at Cedexis, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
"Cloud Academy is an enterprise training platform for the cloud, specifically public clouds. We offer guided learning experiences on AWS, Azure, Google Cloud and all the surrounding methodologies and technologies that you need to know and your teams need to know in order to leverage the full benefits of the cloud," explained Alex Brower, VP of Marketing at Cloud Academy, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clar...
Large industrial manufacturing organizations are adopting the agile principles of cloud software companies. The industrial manufacturing development process has not scaled over time. Now that design CAD teams are geographically distributed, centralizing their work is key. With large multi-gigabyte projects, outdated tools have stifled industrial team agility, time-to-market milestones, and impacted P&L stakeholders.
Gemini is Yahoo’s native and search advertising platform. To ensure the quality of a complex distributed system that spans multiple products and components and across various desktop websites and mobile app and web experiences – both Yahoo owned and operated and third-party syndication (supply), with complex interaction with more than a billion users and numerous advertisers globally (demand) – it becomes imperative to automate a set of end-to-end tests 24x7 to detect bugs and regression. In th...
"Akvelon is a software development company and we also provide consultancy services to folks who are looking to scale or accelerate their engineering roadmaps," explained Jeremiah Mothersell, Marketing Manager at Akvelon, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
"MobiDev is a software development company and we do complex, custom software development for everybody from entrepreneurs to large enterprises," explained Alan Winters, U.S. Head of Business Development at MobiDev, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
SYS-CON Events announced today that CrowdReviews.com has been named “Media Sponsor” of SYS-CON's 22nd International Cloud Expo, which will take place on June 5–7, 2018, at the Javits Center in New York City, NY. CrowdReviews.com is a transparent online platform for determining which products and services are the best based on the opinion of the crowd. The crowd consists of Internet users that have experienced products and services first-hand and have an interest in letting other potential buye...
"IBM is really all in on blockchain. We take a look at sort of the history of blockchain ledger technologies. It started out with bitcoin, Ethereum, and IBM evaluated these particular blockchain technologies and found they were anonymous and permissionless and that many companies were looking for permissioned blockchain," stated René Bostic, Technical VP of the IBM Cloud Unit in North America, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Conventi...
SYS-CON Events announced today that Telecom Reseller has been named “Media Sponsor” of SYS-CON's 22nd International Cloud Expo, which will take place on June 5-7, 2018, at the Javits Center in New York, NY. Telecom Reseller reports on Unified Communications, UCaaS, BPaaS for enterprise and SMBs. They report extensively on both customer premises based solutions such as IP-PBX as well as cloud based and hosted platforms.
"Space Monkey by Vivent Smart Home is a product that is a distributed cloud-based edge storage network. Vivent Smart Home, our parent company, is a smart home provider that places a lot of hard drives across homes in North America," explained JT Olds, Director of Engineering, and Brandon Crowfeather, Product Manager, at Vivint Smart Home, in this SYS-CON.tv interview at @ThingsExpo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
Coca-Cola’s Google powered digital signage system lays the groundwork for a more valuable connection between Coke and its customers. Digital signs pair software with high-resolution displays so that a message can be changed instantly based on what the operator wants to communicate or sell. In their Day 3 Keynote at 21st Cloud Expo, Greg Chambers, Global Group Director, Digital Innovation, Coca-Cola, and Vidya Nagarajan, a Senior Product Manager at Google, discussed how from store operations and ...
It is of utmost importance for the future success of WebRTC to ensure that interoperability is operational between web browsers and any WebRTC-compliant client. To be guaranteed as operational and effective, interoperability must be tested extensively by establishing WebRTC data and media connections between different web browsers running on different devices and operating systems. In his session at WebRTC Summit at @ThingsExpo, Dr. Alex Gouaillard, CEO and Founder of CoSMo Software, presented ...
WebRTC is great technology to build your own communication tools. It will be even more exciting experience it with advanced devices, such as a 360 Camera, 360 microphone, and a depth sensor camera. In his session at @ThingsExpo, Masashi Ganeko, a manager at INFOCOM Corporation, introduced two experimental projects from his team and what they learned from them. "Shotoku Tamago" uses the robot audition software HARK to track speakers in 360 video of a remote party. "Virtual Teleport" uses a multip...
A strange thing is happening along the way to the Internet of Things, namely far too many devices to work with and manage. It has become clear that we'll need much higher efficiency user experiences that can allow us to more easily and scalably work with the thousands of devices that will soon be in each of our lives. Enter the conversational interface revolution, combining bots we can literally talk with, gesture to, and even direct with our thoughts, with embedded artificial intelligence, whic...
SYS-CON Events announced today that Evatronix will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Evatronix SA offers comprehensive solutions in the design and implementation of electronic systems, in CAD / CAM deployment, and also is a designer and manufacturer of advanced 3D scanners for professional applications.
Leading companies, from the Global Fortune 500 to the smallest companies, are adopting hybrid cloud as the path to business advantage. Hybrid cloud depends on cloud services and on-premises infrastructure working in unison. Successful implementations require new levels of data mobility, enabled by an automated and seamless flow across on-premises and cloud resources. In his general session at 21st Cloud Expo, Greg Tevis, an IBM Storage Software Technical Strategist and Customer Solution Architec...
To get the most out of their data, successful companies are not focusing on queries and data lakes, they are actively integrating analytics into their operations with a data-first application development approach. Real-time adjustments to improve revenues, reduce costs, or mitigate risk rely on applications that minimize latency on a variety of data sources. In his session at @BigDataExpo, Jack Norris, Senior Vice President, Data and Applications at MapR Technologies, reviewed best practices to ...
An increasing number of companies are creating products that combine data with analytical capabilities. Running interactive queries on Big Data requires complex architectures to store and query data effectively, typically involving data streams, an choosing efficient file format/database and multiple independent systems that are tied together through custom-engineered pipelines. In his session at @BigDataExpo at @ThingsExpo, Tomer Levi, a senior software engineer at Intel’s Advanced Analytics gr...
When talking IoT we often focus on the devices, the sensors, the hardware itself. The new smart appliances, the new smart or self-driving cars (which are amalgamations of many ‘things’). When we are looking at the world of IoT, we should take a step back, look at the big picture. What value are these devices providing? IoT is not about the devices, it’s about the data consumed and generated. The devices are tools, mechanisms, conduits. In his session at Internet of Things at Cloud Expo | DXWor...