|By Shankar Itchapurapu||
|April 9, 2013 07:45 AM EDT||
The Java Virtual Machine specification limits the size of generated Java byte code for each method in a class to the maximum of 64K bytes. This limitation will cause the JVM to throw java.lang.VerifyError at runtime when the method size exceeds this limit.
This method size restriction of the JVM seems to be too stringent. A bug is open with the Oracle Java development team (http://bugs.sun.com/view_bug.do?bug_id=4262078). This bug is taken as an enhancement request which is likely to be fixed in the future java versions. That said, the fix for this issue is rather supportive. Application/Container developers need to consider few factors and apply good programming/refactoring techniques to get around this problem. While future versions of JVM might increase the method size limit to a considerable extent, a the size will always be a finite value.
In this article, I discuss some of the techniques that can be used to get around this problem. The techniques/suggestions discussed here, while apply to development environments also, are primarily targeted for containers which involve code generation as part of compilation process (e.g., EJB container or a JSP container).
Applications and Method Size Limit
While applications written in Java seldom encounter this issue, even more so after the above noted bug is fixed, it is recommended to follow the proven software engineering principles like code refactoring and object oriented programming techniques.
The complexity of this issue in application development is relatively smaller. As the code is written through the development phase, a number of tests are run both at the Unit level as well as the system level. Also, it is very rare that the application development involves complex code generation during the build time. This gives the developer/architect an opportunity to identify the possible method size restriction issue well ahead of the final delivery.
Application Containers and Method Size Limit
Application Containers are environments where Java applications execute. So they carry very high degree of complexity in terms of code. As the containers consume the application code and configuration and provide services for the application runtime, containers most often involve code generation. This code generation can be very complex in systems like JSP compiler as they convert scripting languages to Java.
This makes containers involving code generation particularly vulnerable to the Java method size limit restriction.
Techniques for Resolving the Method Size Restriction
In this section, I detail some of the techniques which can be used in code generation area to cover most of the use cases which cause the method size restriction.
Splitting a Big Method into Smaller Pieces
This is one of the structured programming techniques which can be used with effect. The driving factor for this technique should be the code refactoring. After the code generation is completed, a careful examination of the bigger methods can give us some clue of moving some of the java statements to a different private method. This is typically reverse engineering the output to a fine grained control.
Using a Intermediate Super Class
This applies particularly to areas such as EJB and JSP. A JSP file once converted into a Java class will typically extend a JspServlet class (implemented differently by different container vendors). The core refactoring technique here is to move the rudimentary code into the super class so that the generated class becomes light. However, this technique is fairly primitive. Most modern container vendors have already optimized their code to include almost everything possible into their super class implementation.
Using Helper Class/Methods
The third refactoring technique is to use a helper class. One particular use case is a JSP compiler handling a [email protected]..% directive. JSP specification mandates that the static includes need to be expanded inline in the generated service method. This adds to the size of the generated service method. One refactoring that can be used here is to move the expanded code into a private member function in the generated Java file and include just the method call in the service method.
Another area is the scripting elements in the JSP file. All the scripting elements are parsed and then included inline in the generated service() method of the java file. A similar refactoring technique discussed above can be used for the scripting elements as well.
Code generation engines can consider generating a Helper class which contains all the refactored methods and shield the Helper class from end-user's direct access.
Using JVM Switches
Java compilers generate .class files, with each file containing bytecodes for the methods in one class. These files contain a series of sections, or attributes, and it's possible to exercise some control over which sections actually show up in a .class file. The Code attribute contains actual bytecodes for methods, SourceFile information on the source file name used to generate this .class file, LineNumberTable mapping information between bytecode offsets and source file line numbers, and LocalVariableTable mapping information between stack frame offsets and local variable names.
We can use options to the javac compiler to control which sections are included:
javac Code, SourceFile, LineNumberTable
javac -g Code, SourceFile, LineNumberTable, LocalVariableTable
javac -g:none Code
How much do these options affect code size? A test using the JDK 1.2.2 sources in the java.io, java.lang, and java.util packages was run, with total sizes of all .class files as follows:
javac -g 815K
javac -g:none 550K
So use of javac -g:none saves about 20% in space over the default javac, and using javac -g is about 20% larger than the default. There are also commercial tools that tackle this particular problem.
If you strip out information such as line numbers from .class files, you may have problems with debugging and exception reporting. So it is recommended that the container vendors provide a configuration mechanism to switch off/on this feature so the production environments can take advantage.
Any refactoring technique will not completely alleviate the method size restriction. Excessive template text and scripting elements in the scripting languages will almost always cause the compilers to generate heavier methods and may lead to the method size restriction. The solution to this problem is supportive. Developers need to concentrate on good programming techniques so that the scripting language code like JSP will be more maintainable. JSP specification recommends using tag libraries that promote reusability while considerably reducing the size of the generated service method.
The Open Connectivity Foundation (OCF), sponsor of the IoTivity open source project, and AllSeen Alliance, which provides the AllJoyn® open source IoT framework, today announced that the two organizations’ boards have approved a merger under the OCF name and bylaws. This merger will advance interoperability between connected devices from both groups, enabling the full operating potential of IoT and representing a significant step towards a connected ecosystem.
Oct. 22, 2016 02:45 AM EDT Reads: 1,142
SYS-CON Media announced today that @WebRTCSummit Blog, the largest WebRTC resource in the world, has been launched. @WebRTCSummit Blog offers top articles, news stories, and blog posts from the world's well-known experts and guarantees better exposure for its authors than any other publication. @WebRTCSummit Blog can be bookmarked ▸ Here @WebRTCSummit conference site can be bookmarked ▸ Here
Oct. 22, 2016 01:30 AM EDT Reads: 9,607
SYS-CON Events announced today that Streamlyzer will exhibit at the 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. Streamlyzer is a powerful analytics for video streaming service that enables video streaming providers to monitor and analyze QoE (Quality-of-Experience) from end-user devices in real time.
Oct. 22, 2016 01:15 AM EDT Reads: 885
You have great SaaS business app ideas. You want to turn your idea quickly into a functional and engaging proof of concept. You need to be able to modify it to meet customers' needs, and you need to deliver a complete and secure SaaS application. How could you achieve all the above and yet avoid unforeseen IT requirements that add unnecessary cost and complexity? You also want your app to be responsive in any device at any time. In his session at 19th Cloud Expo, Mark Allen, General Manager of...
Oct. 22, 2016 01:15 AM EDT Reads: 800
@ThingsExpo has been named the Top 5 Most Influential Internet of Things Brand by Onalytica in the ‘The Internet of Things Landscape 2015: Top 100 Individuals and Brands.' Onalytica analyzed Twitter conversations around the #IoT debate to uncover the most influential brands and individuals driving the conversation. Onalytica captured data from 56,224 users. The PageRank based methodology they use to extract influencers on a particular topic (tweets mentioning #InternetofThings or #IoT in this ...
Oct. 22, 2016 01:00 AM EDT Reads: 8,143
SYS-CON Events announced today that Super Micro Computer, Inc., a global leader in Embedded and IoT solutions, will exhibit at SYS-CON's 20th International Cloud Expo®, which will take place on June 7-9, 2017, at the Javits Center in New York City, NY. Supermicro (NASDAQ: SMCI), the leading innovator in high-performance, high-efficiency server technology, is a premier provider of advanced server Building Block Solutions® for Data Center, Cloud Computing, Enterprise IT, Hadoop/Big Data, HPC and ...
Oct. 22, 2016 12:30 AM EDT Reads: 3,485
Cloud based infrastructure deployment is becoming more and more appealing to customers, from Fortune 500 companies to SMEs due to its pay-as-you-go model. Enterprise storage vendors are able to reach out to these customers by integrating in cloud based deployments; this needs adaptability and interoperability of the products confirming to cloud standards such as OpenStack, CloudStack, or Azure. As compared to off the shelf commodity storage, enterprise storages by its reliability, high-availabil...
Oct. 22, 2016 12:15 AM EDT Reads: 954
Explosive growth in connected devices. Enormous amounts of data for collection and analysis. Critical use of data for split-second decision making and actionable information. All three are factors in making the Internet of Things a reality. Yet, any one factor would have an IT organization pondering its infrastructure strategy. How should your organization enhance its IT framework to enable an Internet of Things implementation? In his session at @ThingsExpo, James Kirkland, Red Hat's Chief Arch...
Oct. 22, 2016 12:00 AM EDT Reads: 5,929
The IoT industry is now at a crossroads, between the fast-paced innovation of technologies and the pending mass adoption by global enterprises. The complexity of combining rapidly evolving technologies and the need to establish practices for market acceleration pose a strong challenge to global enterprises as well as IoT vendors. In his session at @ThingsExpo, Clark Smith, senior product manager for Numerex, will discuss how Numerex, as an experienced, established IoT provider, has embraced a ...
Oct. 22, 2016 12:00 AM EDT Reads: 936
SYS-CON Events announced today that Cloudbric, a leading website security provider, will exhibit at the 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. Cloudbric is an elite full service website protection solution specifically designed for IT novices, entrepreneurs, and small and medium businesses. First launched in 2015, Cloudbric is based on the enterprise level Web Application Firewall by Penta Security Sys...
Oct. 21, 2016 11:45 PM EDT Reads: 983
We are reaching the end of the beginning with WebRTC, and real systems using this technology have begun to appear. One challenge that faces every WebRTC deployment (in some form or another) is identity management. For example, if you have an existing service – possibly built on a variety of different PaaS/SaaS offerings – and you want to add real-time communications you are faced with a challenge relating to user management, authentication, authorization, and validation. Service providers will w...
Oct. 21, 2016 11:45 PM EDT Reads: 3,204
When people aren’t talking about VMs and containers, they’re talking about serverless architecture. Serverless is about no maintenance. It means you are not worried about low-level infrastructural and operational details. An event-driven serverless platform is a great use case for IoT. In his session at @ThingsExpo, Animesh Singh, an STSM and Lead for IBM Cloud Platform and Infrastructure, will detail how to build a distributed serverless, polyglot, microservices framework using open source tec...
Oct. 21, 2016 11:45 PM EDT Reads: 4,412
November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. Penta Security is a leading vendor for data security solutions, including its encryption solution, D’Amo. By using FPE technology, D’Amo allows for the implementation of encryption technology to sensitive data fields without modification to schema in the database environment. With businesses having their data become increasingly more complicated in their mission-critical applications (such as ERP, CRM, HRM), continued ...
Oct. 21, 2016 11:45 PM EDT Reads: 868
You think you know what’s in your data. But do you? Most organizations are now aware of the business intelligence represented by their data. Data science stands to take this to a level you never thought of – literally. The techniques of data science, when used with the capabilities of Big Data technologies, can make connections you had not yet imagined, helping you discover new insights and ask new questions of your data. In his session at @ThingsExpo, Sarbjit Sarkaria, data science team lead ...
Oct. 21, 2016 10:00 PM EDT Reads: 4,219
A completely new computing platform is on the horizon. They’re called Microservers by some, ARM Servers by others, and sometimes even ARM-based Servers. No matter what you call them, Microservers will have a huge impact on the data center and on server computing in general. Although few people are familiar with Microservers today, their impact will be felt very soon. This is a new category of computing platform that is available today and is predicted to have triple-digit growth rates for some ...
Oct. 21, 2016 10:00 PM EDT Reads: 33,896
SYS-CON Events announced today that Roundee / LinearHub will exhibit at the WebRTC Summit at @ThingsExpo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. LinearHub provides Roundee Service, a smart platform for enterprise video conferencing with enhanced features such as automatic recording and transcription service. Slack users can integrate Roundee to their team via Slack’s App Directory, and '/roundee' command lets your video conference ...
Oct. 21, 2016 09:15 PM EDT Reads: 1,983
SYS-CON Events announced today that Enzu will exhibit at the 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. Enzu’s mission is to be the leading provider of enterprise cloud solutions worldwide. Enzu enables online businesses to use its IT infrastructure to their competitive advantage. By offering a suite of proven hosting and management services, Enzu wants companies to focus on the core of their online busine...
Oct. 21, 2016 09:15 PM EDT Reads: 1,200
SYS-CON Events announced today that SoftNet Solutions will exhibit at the 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. SoftNet Solutions specializes in Enterprise Solutions for Hadoop and Big Data. It offers customers the most open, robust, and value-conscious portfolio of solutions, services, and tools for the shortest route to success with Big Data. The unique differentiator is the ability to architect and...
Oct. 21, 2016 08:15 PM EDT Reads: 363
Why do your mobile transformations need to happen today? Mobile is the strategy that enterprise transformation centers on to drive customer engagement. In his general session at @ThingsExpo, Roger Woods, Director, Mobile Product & Strategy – Adobe Marketing Cloud, covered key IoT and mobile trends that are forcing mobile transformation, key components of a solid mobile strategy and explored how brands are effectively driving mobile change throughout the enterprise.
Oct. 21, 2016 07:15 PM EDT Reads: 1,620
In past @ThingsExpo presentations, Joseph di Paolantonio has explored how various Internet of Things (IoT) and data management and analytics (DMA) solution spaces will come together as sensor analytics ecosystems. This year, in his session at @ThingsExpo, Joseph di Paolantonio from DataArchon, will be adding the numerous Transportation areas, from autonomous vehicles to “Uber for containers.” While IoT data in any one area of Transportation will have a huge impact in that area, combining senso...
Oct. 21, 2016 07:15 PM EDT Reads: 283