Welcome!

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

Related Topics: Weblogic

Weblogic: Article

The Grinder: Load Testing for Everyone

The Grinder: Load Testing for Everyone

The Grinder is an easy-to-use Java-based load generation and performance measurement tool that adapts to a wide range of J2EE applications. If you have a J2EE performance measurement requirement, The Grinder will probably fit the bill.

Paco Gómez developed the original version of The Grinder for Professional Java 2 Enterprise Edition with BEA WebLogic Server (Wrox Press, 2000). I took ownership of the source code at the end of 2000 and began The Grinder 2 stream of development. The Grinder is freely available under a BSD-style license.

This article will introduce only the basic features of The Grinder. I encourage you to download the tool and try it out. The recently published J2EE Performance Testing by Peter Zadrozny, Ted Osborne, and me (Expert Press, 2002) contains much more information about The Grinder.

Where to Obtain The Grinder
You can download The Grinder distribution from The Grinder home page at http://grinder.sourceforge.net. The examples in this article were run using The Grinder 2.8.3.

There are some mailing lists that you can join to become a part of The Grinder community:

  • grinder-announce: Low-volume notifications of new releases
  • grinder-use: The place to ask for help
  • grinder-development: For those interested in developing The Grinder
So, What Is The Grinder?
In short, The Grinder is a framework for generating load by simulating client requests to your application, and for measuring how your application copes with that load.

Typically, you will have begged, bought, or borrowed a number of test-client machines with which to test your application. You can use The Grinder console to control many processes across your test-client machines, each running many threads of control. The Grinder is a pure Java application, so there's a wide variety of platforms that you can use.

Three types of processes make up The Grinder:

  • Agent processes: A single agent process runs on each test-client machine and is responsible for managing the worker processes on that machine.

  • Worker processes: Created by The Grinder agent processes, they are responsible for performing the tests.

  • The console: Coordinates the other processes and collates statistics.

    Each of these processes is a Java Virtual Machine (JVM) and can be run on any computer with a suitable version of Java installed.

    To run a given set of tests, an agent process is started on each test-client machine. This process is responsible for creating a number of worker processes. Each loads a plug-in component that determines the type of tests to run and then starts a number of worker threads. For example, with the provided HTTP plug-in each test corresponds to an HTTP request to a URL. Each of the worker threads uses the plug-in to execute tests.

    The grinder.properties file is a configuration file that is read by the agent and worker processes, and the plug-in. This file contains all the information necessary to run a particular set of tests, such as the number of worker processes, the number of worker threads, and the plug-in to use. For most plug-ins, the file also specifies the tests to run and can be thought of as the "test script." For example, when using the HTTP plug-in, the grinder.properties file contains the URL for each test.

    The agent process and the worker processes read their configuration from grinder.properties when they are started (see Figure 1). I usually put the grinder.properties file on a shared network drive so I don't have to copy it to each of the test-client machines.

    The net effect of this scheme is to allow the easy configuration of many separate client contexts, each of which will run the same set of tests against your server or servers. Each context simulates an active user session. The number of contexts is given by the following formula:

    (Number of agent processes) x (Number of worker processes)
    x (Number of worker threads)

    The Console
    The Grinder console (see Figure 2) provides an easy way to control multiple test-client machines, display test results, and control test runs.

    The console is used to coordinate the actions of the worker processes by sending them start, reset, and stop commands. IP multicast is used to broadcast the commands simultaneously to processes running on many machines. The worker processes send statistics reports to the console, which combines these reports to produce graphs and tables showing test activity. The results of a particular test run can be saved for further analysis.

    The console also calculates and displays derived statistics. A key derived statistic that the console can calculate, but the individual worker processes cannot, is a combined transactions per second (TPS) figure for all the worker processes. This is because a rate, such as TPS, can't be calculated without a shared notion of the beginning and the end of the timing period. The console performs the required timekeeping function.

    Getting Started
    Have I whetted your appetite? Let's try running The Grinder. In this example, we'll start both the console and an agent process on a single machine.

    Having expanded The Grinder distribution and set up your CLASSPATH appropriately (see the README file provided with The Grinder for details), you can start the console with the following command:

    $ java net.grinder.Console.

    The console window should appear. Now change to a directory to hold the output of the worker processes and create a grinder.properties file:

    grinder.processes=2
    grinder.threads=5

    grinder.plugin=net.grinder.plugin.http.HttpPlugin

    grinder.test0.parameter.url=\
    http://e-docs.bea.com/wlsdocs70/index.html
    grinder.test1.parameter.url=\
    http://e-docs.bea.com/wlsdocs70/images/bealogo.gif

    This particular file specifies that there will be two worker processes with five worker threads each, and that the HTTP plug-in will be used. It also defines two tests that involve accessing resources from the BEA e-docs site.

    Start the agent process in the same directory as the grinder.properties file :

    $ java net.grinder.Grinder

    The console display will update to show the two tests. To instruct the worker processes to start the test run, select Start processes from the Action menu. After a short delay, the console display will show graphs of the incoming reports.

    Individual graphs will show the TPS for each test, and a full graph will show the total TPS. Alongside each graph, the mean transaction time, mean transactions per second, peak transactions per second, number of transactions, and number of errors recorded for each test are shown. The colors of the individual test graphs vary from yellow to red to indicate the tests that have the longest mean transaction times. The more red a test graph is, the longer the transactions for that test are taking.

    Try selecting the Results tab to see the results in a tabular form. You can also select the Sample tab to show the sum of all reports received during the current console sample interval.

    Note: If this example doesn't work the first time, it's usually something straightforward. Have a look though the documentation that comes with The Grinder, and if that doesn't help you, e-mail [email protected].

    Recording Test Scripts
    It's quite feasible to have HTTP plug-in grinder.properties test scripts containing hundreds or thousands of individual tests. The Grinder lets you specify the timing of each test. Additionally, the HTTP plug-in provides support for setting cookies, authentication information, dynamically generated requests, HTTPS, and other HTTP features. All of these are configured using properties in the grinder.properties file.

    Writing such test scripts by hand quickly becomes impractical. The Grinder is shipped with a tool, the TCP Sniffer, that can automatically capture test-script entries corresponding to the HTTP requests a user makes using a browser, and generate corresponding test-script entries. The TCP Sniffer is configured to sit between the user's browser and the target server and capture all the requests the browser makes before proxying the requests on to the server. (Technically the TCP Sniffer is a proxy and not a sniffer at all, but it's very useful despite being misnamed!) The responses the TCP Sniffer receives from the server are returned to the browser.

    You can start the TCP Sniffer in a special mode in which it outputs a recording of the requests you make with the browser as a full grinder.properties test script. You can then take this test script and replay it using The Grinder.

    More Than HTTP
    While the HTTP plug-in is the most commonly used, The Grinder can also be used in contexts other than Web and Web-services testing. Two other example plug-ins are shipped with The Grinder, a JUnit plug-in that allows you to repeatedly exercise a JUnit test case using many threads, and a raw socket plug-in.

    It's also easy to write your own plug-in - you just provide a Java class that conforms to a simple interface. I often do this to test J2EE applications with EJB or a JMS interface.

    The Grinder is already a powerful tool, but it can be improved. One of the key limitations is that each worker process executes the tests in the test script sequentially, in a fixed order. The Grinder 3 will address this by allowing tests to be specified using a variety of scripting languages, including Visual Basic, Jython, and JavaScript. Test scripts will allow arbitrary branching and looping, perhaps using the scripting languages' support for random variables. That's if I can find the hacking time.

    Happy grinding!

    Acknowledgements
    I am grateful to Tony Davis and the Expert Press team for their permission to use material from J2EE Performance Testing. As well as full coverage of The Grinder, this book contains much practical information about J2EE performance and application benchmarking.

    I also wish to express gratitude to VA Software for the SourceForge site (http://sourceforge.net/). SourceForge is without doubt a great resource for the open source community and is responsible for the continued success of The Grinder and many other open-source projects.

  • Comments (0)

    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.


    @ThingsExpo Stories
    The 22nd International Cloud Expo | 1st DXWorld Expo has announced that its Call for Papers is open. Cloud Expo | DXWorld Expo, to be held June 5-7, 2018, at the Javits Center in New York, NY, brings together Cloud Computing, Digital Transformation, Big Data, Internet of Things, DevOps, Machine Learning and WebRTC to one location. With cloud computing driving a higher percentage of enterprise IT budgets every year, it becomes increasingly important to plant your flag in this fast-expanding busin...
    SYS-CON Events announced today that Synametrics Technologies will exhibit at SYS-CON's 22nd International Cloud Expo®, which will take place on June 5-7, 2018, at the Javits Center in New York, NY. Synametrics Technologies is a privately held company based in Plainsboro, New Jersey that has been providing solutions for the developer community since 1997. Based on the success of its initial product offerings such as WinSQL, Xeams, SynaMan and Syncrify, Synametrics continues to create and hone inn...
    Smart cities have the potential to change our lives at so many levels for citizens: less pollution, reduced parking obstacles, better health, education and more energy savings. Real-time data streaming and the Internet of Things (IoT) possess the power to turn this vision into a reality. However, most organizations today are building their data infrastructure to focus solely on addressing immediate business needs vs. a platform capable of quickly adapting emerging technologies to address future ...
    No hype cycles or predictions of a gazillion things here. IoT is here. You get it. You know your business and have great ideas for a business transformation strategy. What comes next? Time to make it happen. In his session at @ThingsExpo, Jay Mason, an Associate Partner of Analytics, IoT & Cybersecurity at M&S Consulting, presented a step-by-step plan to develop your technology implementation strategy. He also discussed the evaluation of communication standards and IoT messaging protocols, data...
    Product connectivity goes hand and hand these days with increased use of personal data. New IoT devices are becoming more personalized than ever before. In his session at 22nd Cloud Expo | DXWorld Expo, Nicolas Fierro, CEO of MIMIR Blockchain Solutions, will discuss how in order to protect your data and privacy, IoT applications need to embrace Blockchain technology for a new level of product security never before seen - or needed.
    In his session at 21st Cloud Expo, Raju Shreewastava, founder of Big Data Trunk, provided a fun and simple way to introduce Machine Leaning to anyone and everyone. He solved a machine learning problem and demonstrated an easy way to be able to do machine learning without even coding. Raju Shreewastava is the founder of Big Data Trunk (www.BigDataTrunk.com), a Big Data Training and consulting firm with offices in the United States. He previously led the data warehouse/business intelligence and B...
    Cloud Expo | DXWorld Expo have announced the conference tracks for Cloud Expo 2018. Cloud Expo will be held June 5-7, 2018, at the Javits Center in New York City, and November 6-8, 2018, at the Santa Clara Convention Center, Santa Clara, CA. Digital Transformation (DX) is a major focus with the introduction of DX Expo within the program. Successful transformation requires a laser focus on being data-driven and on using all the tools available that enable transformation if they plan to survive ov...
    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...
    "Evatronix provides design services to companies that need to integrate the IoT technology in their products but they don't necessarily have the expertise, knowledge and design team to do so," explained Adam Morawiec, VP of Business Development at Evatronix, in this SYS-CON.tv interview at @ThingsExpo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
    Recently, REAN Cloud built a digital concierge for a North Carolina hospital that had observed that most patient call button questions were repetitive. In addition, the paper-based process used to measure patient health metrics was laborious, not in real-time and sometimes error-prone. In their session at 21st Cloud Expo, Sean Finnerty, Executive Director, Practice Lead, Health Care & Life Science at REAN Cloud, and Dr. S.P.T. Krishnan, Principal Architect at REAN Cloud, discussed how they built...
    Digital Transformation (DX) is not a "one-size-fits all" strategy. Each organization needs to develop its own unique, long-term DX plan. It must do so by realizing that we now live in a data-driven age, and that technologies such as Cloud Computing, Big Data, the IoT, Cognitive Computing, and Blockchain are only tools. In her general session at 21st Cloud Expo, Rebecca Wanta explained how the strategy must focus on DX and include a commitment from top management to create great IT jobs, monitor ...
    "Digital transformation - what we knew about it in the past has been redefined. Automation is going to play such a huge role in that because the culture, the technology, and the business operations are being shifted now," stated Brian Boeggeman, VP of Alliances & Partnerships at Ayehu, 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.
    In his Opening Keynote at 21st Cloud Expo, John Considine, General Manager of IBM Cloud Infrastructure, led attendees through the exciting evolution of the cloud. He looked at this major disruption from the perspective of technology, business models, and what this means for enterprises of all sizes. John Considine is General Manager of Cloud Infrastructure Services at IBM. In that role he is responsible for leading IBM’s public cloud infrastructure including strategy, development, and offering m...
    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.
    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 ...
    Recently, WebRTC has a lot of eyes from market. The use cases of WebRTC are expanding - video chat, online education, online health care etc. Not only for human-to-human communication, but also IoT use cases such as machine to human use cases can be seen recently. One of the typical use-case is remote camera monitoring. With WebRTC, people can have interoperability and flexibility for deploying monitoring service. However, the benefit of WebRTC for IoT is not only its convenience and interopera...
    Nordstrom is transforming the way that they do business and the cloud is the key to enabling speed and hyper personalized customer experiences. In his session at 21st Cloud Expo, Ken Schow, VP of Engineering at Nordstrom, discussed some of the key learnings and common pitfalls of large enterprises moving to the cloud. This includes strategies around choosing a cloud provider(s), architecture, and lessons learned. In addition, he covered some of the best practices for structured team migration an...
    With tough new regulations coming to Europe on data privacy in May 2018, Calligo will explain why in reality the effect is global and transforms how you consider critical data. EU GDPR fundamentally rewrites the rules for cloud, Big Data and IoT. In his session at 21st Cloud Expo, Adam Ryan, Vice President and General Manager EMEA at Calligo, examined the regulations and provided insight on how it affects technology, challenges the established rules and will usher in new levels of diligence arou...
    22nd International Cloud Expo, taking place June 5-7, 2018, at the Javits Center in New York City, NY, and co-located with the 1st DXWorld Expo will feature technical sessions from a rock star conference faculty and the leading industry players in the world. Cloud computing is now being embraced by a majority of enterprises of all sizes. Yesterday's debate about public vs. private has transformed into the reality of hybrid cloud: a recent survey shows that 74% of enterprises have a hybrid cloud ...
    22nd International Cloud Expo, taking place June 5-7, 2018, at the Javits Center in New York City, NY, and co-located with the 1st DXWorld Expo will feature technical sessions from a rock star conference faculty and the leading industry players in the world. Cloud computing is now being embraced by a majority of enterprises of all sizes. Yesterday's debate about public vs. private has transformed into the reality of hybrid cloud: a recent survey shows that 74% of enterprises have a hybrid cloud ...