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
    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...
    BnkToTheFuture.com is the largest online investment platform for investing in FinTech, Bitcoin and Blockchain companies. We believe the future of finance looks very different from the past and we aim to invest and provide trading opportunities for qualifying investors that want to build a portfolio in the sector in compliance with international financial regulations.
    Imagine if you will, a retail floor so densely packed with sensors that they can pick up the movements of insects scurrying across a store aisle. Or a component of a piece of factory equipment so well-instrumented that its digital twin provides resolution down to the micrometer.
    In his keynote at 18th Cloud Expo, Andrew Keys, Co-Founder of ConsenSys Enterprise, provided an overview of the evolution of the Internet and the Database and the future of their combination – the Blockchain. Andrew Keys is Co-Founder of ConsenSys Enterprise. He comes to ConsenSys Enterprise with capital markets, technology and entrepreneurial experience. Previously, he worked for UBS investment bank in equities analysis. Later, he was responsible for the creation and distribution of life settle...
    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.
    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...
    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...
    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...
    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 ...
    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...
    "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...
    When shopping for a new data processing platform for IoT solutions, many development teams want to be able to test-drive options before making a choice. Yet when evaluating an IoT solution, it’s simply not feasible to do so at scale with physical devices. Building a sensor simulator is the next best choice; however, generating a realistic simulation at very high TPS with ease of configurability is a formidable challenge. When dealing with multiple application or transport protocols, you would be...
    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 ...
    We are given a desktop platform with Java 8 or Java 9 installed and seek to find a way to deploy high-performance Java applications that use Java 3D and/or Jogl without having to run an installer. We are subject to the constraint that the applications be signed and deployed so that they can be run in a trusted environment (i.e., outside of the sandbox). Further, we seek to do this in a way that does not depend on bundling a JRE with our applications, as this makes downloads and installations rat...
    Widespread fragmentation is stalling the growth of the IIoT and making it difficult for partners to work together. The number of software platforms, apps, hardware and connectivity standards is creating paralysis among businesses that are afraid of being locked into a solution. EdgeX Foundry is unifying the community around a common IoT edge framework and an ecosystem of interoperable components.
    DX World EXPO, LLC, a Lighthouse Point, Florida-based startup trade show producer and the creator of "DXWorldEXPO® - Digital Transformation Conference & Expo" has announced its executive management team. The team is headed by Levent Selamoglu, who has been named CEO. "Now is the time for a truly global DX event, to bring together the leading minds from the technology world in a conversation about Digital Transformation," he said in making the announcement.
    In this strange new world where more and more power is drawn from business technology, companies are effectively straddling two paths on the road to innovation and transformation into digital enterprises. The first path is the heritage trail – with “legacy” technology forming the background. Here, extant technologies are transformed by core IT teams to provide more API-driven approaches. Legacy systems can restrict companies that are transitioning into digital enterprises. To truly become a lead...
    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 ...
    "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...
    The IoT Will Grow: In what might be the most obvious prediction of the decade, the IoT will continue to expand next year, with more and more devices coming online every single day. What isn’t so obvious about this prediction: where that growth will occur. The retail, healthcare, and industrial/supply chain industries will likely see the greatest growth. Forrester Research has predicted the IoT will become “the backbone” of customer value as it continues to grow. It is no surprise that retail is ...