Book Image

JBoss AS 5 Performance Tuning

By : Francesco Marchioni, Jason Savod
Book Image

JBoss AS 5 Performance Tuning

By: Francesco Marchioni, Jason Savod

Overview of this book

Today's organizations need to deliver faster services to a large set of people and businesses. In order to survive this challenge, enterprises need to optimize the performance of their application server along with its components and hardware. Writing faster applications is no longer just an option for your products; it's an imperative requirement, which you cannot ignore. JBoss AS 5 Performance Tuning will teach you how to deliver fast applications on the JBoss Application Server and Apache Tomcat, giving you a decisive competitive advantage over your competitors. You will learn how to optimize the hardware resources, meeting your application requirements with less expenditure.The performance of Java Enterprise applications is the sum of a set of components including the Java Virtual Machine configuration, the application server configuration (in our case, JBoss AS), the application code itself and ultimately the operating system. This book will show you how to apply the correct tuning methodology and use the tuning tools that will help you to monitor and address any performance issues. By looking more closely at the Java Virtual Machine, you will get a deeper understanding of what the available options are for your applications and how their performance will be affected. You will learn about thread pool tuning, EJB tuning, JMS tuning, Enterprise Java Beans, and the Java Messaging Service. The persistence layer and JBoss Clustering service each have a chapter dedicated to them as they are two of the most crucial elements to configure correctly in order to run a fast application. You will also learn how to tune your web server, enabling you to configure and develop web applications that get the most out of the embedded Tomcat web server.
Table of Contents (17 chapters)
JBoss AS 5 Performance Tuning
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
A Tuned Mind
Index

Tuning Java Enterprise applications


One of the most pervasive myths about Java Enterprise applications is that they simply are slow. The notion of Java being "slow" in popular discussions is often poorly calibrated but, unfortunately, widely believed. The most compelling reason for this sentiment dates back to the first releases of Java Development Kit. In 1995, Java was much slower as the first implementations of the Java Virtual Machine didn't have a Just In Time complier, the garbage collector algorithms were not so refined and, generally speaking, lots of applications were written using classes with poor performance numbers (for example, Input/Output streams without buffering, or abuse of thread-safe collections classes like the java.io.Vector).

While the debate continues in many forums, featuring benchmarks generally with the "elder brother" C++, there is some truth in it; that is today (some time ago), many Java applications are still awfully slow. Why?

What happened is that, ironically, even if Sun engineers were able to deliver faster JVMs release after release, programming Java Enterprise applications became more and more complex, and therefore so did writing fast Java applications.

Not so long ago the archetype of a Java Application was made up of a Front Layer (usually developed with JSPs or Swing) and some Middleware, usually developed with a mix of Servlets and Data Access Objects (DAO) that contained the interfaces for the legacy system.

In such a scenario, the architect had to take care of fewer counters and there was only one, or perhaps two protocols involved in the communications (HTTP and RMI).With a minimal application and web server tuning along with some DBA tips you could bring home the desired result.

Today's enterprise applications are much more complex; take for example the input: it can come from HTML as well as a thick client or a web service, or even a mobile device. Also, lots of Java programming interfaces have been screened by other frameworks to simplify or enhance the productivity of the developer. For example, Java Server Faces (JSF) specification has been built on the top of Servlet/JSPs and then custom libraries (like RichFaces) have been built on the top of JSF. Another good example is the Hibernate framework, which has been built on the top of JDBC, and then Entities have been built on the top of Hibernate.

We might continue discussing other good examples, however the truth is that each of these extra layers inevitably carry some overhead, and have their own best practices which are usually unknown to the majority of developers.

Our conclusion is that today Java applications have a higher performance potential than they once did, but this needs expert hands and a solid tuning methodology to be allowed in the Eden where fast applications live.

Nevertheless, tuning Java Enterprise applications is more complex than standalone applications as it requires monitoring and configuring additional components like the application server, which acts as a container for the application, and all resources which are directly controlled by the application server. In the next section, we are going to explore all the single areas which have an impact on the performance of an enterprise application.

Areas of tuning

Configuration and tuning settings can be divided into four main categories:

  • Java Virtual Machine (JVM) tuning

  • Middleware tuning

  • Application tuning

  • Operating system / Hardware tuning

Let's enter more in detail in each area:

  • JVM tuning: Every Java application runs in a Virtual Machine, so with proper configuration of JVM parameters (in particular those related to memory and garbage collection), it's possible to achieve better performance of your Java applications. The configuration of JVM has changed a lot since the first releases of Java, and most developers are not aware that the default JVM parameters are usually not optimal for running large applications. We will cover this topic in more detail in Chapter 3, Core JVM tuning, which is entirely dedicated to JVM tuning.

  • Middleware tuning is managed to control how an application server provides services for running applications and their components. The application server is pretty complex stuff and at the same time, a fertile ground for optimizations for expert users. The application server contains a core configuration that is common to all applications (think about the pool of thread which is responsible for invoking other components), and also a set of Java EE services which are available for use (like EJB, the web container, JMS, and so on). Each of these services has a default configuration which can be just as good for average applications, but need to be tweaked in order to obtain superior performance.

  • Application tuning requires that you write efficient code in your application, as well as adopt the best performing libraries to achieve the desired task.

    Most tuning experts agree that application tuning accounts for about 75% of the overall tuning process. This doesn't mean that hardware and correct administration configuration is useless. The truth is that even the best hardware and application server configuration will not provide dramatic performance numbers if you are running a poorly coded application. Just to mention a few:

    • Are you using queries without index on the where fields?

    • Are you gathering massive data in the HTTP session?

    • Are you issuing a select * and trying to cache all the data in the middle tier

    If you are performing any of these mistakes then there is little you can fix with proper JVM configuration or application server tuning alone.

  • Operating system tuning relates to configuring your system and hardware resources so that they can efficiently run the software resources discussed previously. The most common hardware tuning is concerned with physical memory: if you determine that your application has a memory bottleneck, and it's not caused by inefficient coding, you have no other choice but to add more memory to your machine(s).

    Another hot point for tuning hardware is CPU: each application that runs on a server gets a time slice of the CPU. The CPU might be able to efficiently handle all of the processes running on the computer, or it might be overloaded. By examining processor activity and the activity of individual processes including thread creation, thread switching, context switching, and so on, you can gain good insight into processor workload and performance. Again, if the CPU is the bottleneck and it cannot be solved by application tuning, you have to consider adding more CPUs or splitting the load on an array of servers.

  • Hardware tuning also includes input/output tuning. Executing long-running file I/O operations, data encryption and decryption, or reading too much data from database tables can turn I/O operation into a serious bottleneck. A shortage of physical memory might also lead to an excessive input-output activity if the data cannot fit in the physical memory. Slow hard disks are another factor to consider and are the only possible solution if you still have disk I/O bottlenecks after optimizing all other factors.

The last hardware component we need to mention is the Network, which is the means by which different applications communicate. Tuning the network means shortening the number of hops your application needs to do in order to reach external systems. You also need to configure your protocol transmission in the most efficient way so that in turn your packets are routed in the most efficient way. Again, if you still have a bottleneck in this area, the last solution is to upgrade to a new set of network devices.

Tip

Is it possible to optimize all areas of tuning?

Theoretically yes, but in practice, optimization will generally focus on improving just one or two aspects of performance: for example execution time, memory usage, disk space, bandwidth, power consumption, or some other resource. This will usually require a trade-off where one factor is optimized at the expense of others. For example, increasing the size of cache improves runtime performance, but also increases the memory consumption. Other common trade-offs include code clarity and conciseness. In practice you have to define some priorities and code accordingly.

The following image synthesizes the concepts we have just covered: