Welcome!

Java IoT Authors: Liz McMillan, Yeshim Deniz, Yakov Fain, Elizabeth White, Thanh Tran

Related Topics: Java IoT, IBM Cloud, Weblogic

Java IoT: Article

Java vs C++ "Shootout" Revisited

Java vs C++ "Shootout" Revisited

Keith Lea writes of the benchmark, on his results page, "I was sick of hearing people say Java was slow, when I know it's pretty fast, so I took the benchmark code for C++ and Java from the now outdated Great Computer Language Shootout and ran the tests myself."

Lea used G++ (GCC) 3.3.1 20030930 (with glibc 2.3.2-98) for the C++, with the -O2 flag (for both i386 and i686). He compiled the Java code normally with the Sun Java 1.4.2_01 compiler, and ran it with the Sun 1.4.2_01 JVM. He ran the tests on Red Hat Linux 9 / Fedora Test1 with the 2.4.20-20.9 kernel on a T30 laptop. The laptop "has a Pentium 4 mobile chip, 512MB of memory, a sort of slow disk," he notes.

The results he got were that Java is significantly faster than optimized C++ in many cases.

"They also show that no one should ever run the client JVM when given the choice," Lea adds. ("Everyone has the choice," he says. To run the server VM, see instructions in the Using the Server JVM section below.)

JDJ has agreed to post online anyone else's results as long as they use Java 1.4.2 or higher and any version of GCC that produces faster or equivalent code than the 3.3.1 I used. We encourage you to download the source and/or the binaries and perform the tests yourself, with your favorite compiler and on your favorite platform.


Lea's Data and Results

JVM startup time was included in these results. "That means even with JVM startup time, Java is still faster than C++ in many of these tests," says Lea.

Some of the C++ tests would not compile. "I've never been very good at decoding GCC's error messages," he admits, "so if I couldn't fix a test with a trivial modification, I didn't include it in my benchmarks."

Lea also modified one of the tests, the string concatenation test for Java.

"The test was creating a new StringBuffer in each iteration of the loop, which was just silly," he explains. "I updated the code to use a single StringBuffer and appending to it inside the loop."

(The updated tests at the original shootout use this new method.)

"Java lost this benchmark even with the modifications," Lea declares. "So if anyone wants to accuse me of biasing the results, they're going to have to try harder."

Several versions of some of the C++ tests (like matrix) were present in the original shootout source, he continues. 

"I used the versions without numbers in them, like matrix.g++ instead of matrix.g++2. I don't know which of these were used in the original benchmarks, but from my quick experimenting, the numberless ones generally ran faster than their numbered counterparts."

"Looking at them again," Lea says, "matrix.g++3 runs faster than the matrix.g++ that I use. However, it still runs slower than the Java version, so I don't plan to modify the graph/data unless someone asks me to, since getting that graph in the first place was sort of a pain.)"

He continues: "I've been told that the C++ code for the Method Call benchmark returns by value while the Java code returns by reference, and that modifying the C++ code to pass a pointer makes that benchmark faster. However, even with the modification, the C++ version still runs slower than the Java version."

Lea ran th Java and the C++ tests to "warm up" (both the Java and C++ tests got faster after he ran them a few times).

"I've been told that these tests are invalid because they were run with GCC," he concedes, adding: "I have seen both benchmarks that show GCC producing faster code than Visual Studio's VC++ compiler, and benchmarks showing the opposite. If I update the benchmarks with another compiler added, it will be the Intel C++ Compiler, which I'm pretty sure produces faster code than VC++."

Lea says he's been accused of biasing the results by using the -O2 option for GCC, "supposedly because -O2 optimizes for space, thus slowing down the benchmark," he explains.

But this is not what -O2 does, he points out, referring to the GCC -O documentation:

JVM startup time was included in these results. "That means even with JVM startup time, Java is still faster than C++ in many of these tests," says Lea.

Some of the C++ tests would not compile. "I've never been very good at decoding GCC's error messages," he admits, "so if I couldn't fix a test with a trivial modification, I didn't include it in my benchmarks."

Lea also modified one of the tests, the string concatenation test for Java.

"The test was creating a new StringBuffer in each iteration of the loop, which was just silly," he explains. "I updated the code to use a single StringBuffer and appending to it inside the loop."

(The updated tests at the original shootout use this new method.)

"Java lost this benchmark even with the modifications," Lea declares. "So if anyone wants to accuse me of biasing the results, they're going to have to try harder."

Several versions of some of the C++ tests (like matrix) were present in the original shootout source, he continues. 

"I used the versions without numbers in them, like matrix.g++ instead of matrix.g++2. I don't know which of these were used in the original benchmarks, but from my quick experimenting, the numberless ones generally ran faster than their numbered counterparts."

"Looking at them again," Lea says, "matrix.g++3 runs faster than the matrix.g++ that I use. However, it still runs slower than the Java version, so I don't plan to modify the graph/data unless someone asks me to, since getting that graph in the first place was sort of a pain.)"

He continues: "I've been told that the C++ code for the Method Call benchmark returns by value while the Java code returns by reference, and that modifying the C++ code to pass a pointer makes that benchmark faster. However, even with the modification, the C++ version still runs slower than the Java version."

Lea ran the tests many times before running the "official" recorded set of tests, so there was plenty of time for both Java and the C++ tests to "warm up" (both the Java and C++ tests got faster after he ran them a few times).

"I've been told that these tests are invalid because they were run with GCC," he concedes, adding: "I have seen both benchmarks that show GCC producing faster code than Visual Studio's VC++ compiler, and benchmarks showing the opposite. If I update the benchmarks with another compiler added, it will be the Intel C++ Compiler, which I'm pretty sure produces faster code than VC++."

Lea says he's been accused of biasing the results by using the -O2 option for GCC, "supposedly because -O2 optimizes for space, thus slowing down the benchmark," he explains.

But this is not what -O2 does, he points out, referring to the GCC -O documentation:

-O2: Optimize even more. GCC performs nearly all supported optimizations that do not involve a space-speed tradeoff. The compiler does not perform loop unrolling or function inlining when you specify -O2. As compared to -O, this option increases both compilation time and the performance of the generated code.

"On the other hand, -O3 performs space-speed tradeoffs, and -O performs fewer optimizations. Thus, for these tests, I think O2 was the best choice," Lea concludes.

 

"I don't have an automated means of building and benchmarking these things (and the scripts that came with the original shootout didn't run for me)," he continues. "I really do want people to test it on their own machines, but it's going to take some work, I guess."

Lea compiled the C++ code with:

g++ [test].cpp -O2 -march=i386 -o [test]-386

g++ [test].cpp -O2 -march=i686 -o [test]-686

and the Java code with:

javac [test].java

To see how he ran the binaries, see the run log. You can download the source code he used in either .bz2 or .zip format.

Using the Server JVM

Every form of Sun's Java runtime comes with both the "client VM" and the "server VM."

"Unfortunately, Java applications and applets run by default in the client VM," Lea observes. "The Server VM is much faster than the Client VM, but it has the downside of taking around 10% longer to start up, and it uses more memory."

Lea explains the two ways to run Java applications with the server VM as follows

  1. When launching a Java application from the command line, use java -server [arguments...] instead of java [arguments...]. For example, use java -server -jar beanshell.jar.
  2. Modify the jvm.cfg file in your Java installation. (It's a text file, so you can use Notepad or Emacs to edit it.) This is located in C:\Program Files\Java\j2reXXX\lib\i386\ on Windows, /usr/java/j2reXXX/lib/i386/ on Linux. You will see two lines:
    -client KNOWN
    -server KNOWN
    You should change them to:
    -server KNOWN
    -client KNOWN
    This change will cause the server VM to be run for all applications, unless they are run with the -client argument.

He can be contacted at

Every form of Sun's Java runtime comes with both the "client VM" and the "server VM."

"Unfortunately, Java applications and applets run by default in the client VM," Lea observes. "The Server VM is much faster than the Client VM, but it has the downside of taking around 10% longer to start up, and it uses more memory."

Lea explains the two ways to run Java applications with the server VM as follows

  1. When launching a Java application from the command line, use java -server [arguments...] instead of java [arguments...]. For example, use java -server -jar beanshell.jar.
  2. Modify the jvm.cfg file in your Java installation. (It's a text file, so you can use Notepad or Emacs to edit it.) This is located in C:\Program Files\Java\j2reXXX\lib\i386\ on Windows, /usr/java/j2reXXX/lib/i386/ on Linux. You will see two lines:
    -client KNOWN
    -server KNOWN
    You should change them to:
    -server KNOWN
    -client KNOWN
    This change will cause the server VM to be run for all applications, unless they are run with the -client argument.

He can be contacted at [email protected].

Links

More Stories By Jeremy Geelan

Jeremy Geelan is Chairman & CEO of the 21st Century Internet Group, Inc. and an Executive Academy Member of the International Academy of Digital Arts & Sciences. Formerly he was President & COO at Cloud Expo, Inc. and Conference Chair of the worldwide Cloud Expo series. He appears regularly at conferences and trade shows, speaking to technology audiences across six continents. You can follow him on twitter: @jg21.

Comments (152) 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
B Bennett 06/15/04 06:25:37 PM EDT

Mr Salarian and people with similar questions should consult the methodology notes from the original shootout (whose code was borrowed for this test) at

http://www.bagley.org/~doug/shootout/method.shtml

That should help clarify what exactly is getting tested, and by what methods.

A. Salarian 06/15/04 06:01:52 PM EDT

Sir, with all due respect I have to say your benchmark is worthless. You have note compared a single C++ program to a Java program. The codes you have tested do not show anything. Why not some real world situation on WHY people use C++ but not Java? Like some complex matrix operations using template based libraries like Blitz++ and equivalent Java industry level Matrix libs? Some applications with a large number of dynamic allocations and deallocations like a dynamic patricia tri in a LZW implementaion? Why not largescale FFTs to test the efficiency of cache management? Why you didn''t use the instrumented C++ (i.e. using the profiling guided compilations)?
You can get any result you wish as long as you don''t test any real world code...

@ThingsExpo Stories
SYS-CON Events announced today that BMC Software has been named "Siver Sponsor" of SYS-CON's 18th Cloud Expo, which will take place on June 7-9, 2015 at the Javits Center in New York, New York. BMC is a global leader in innovative software solutions that help businesses transform into digital enterprises for the ultimate competitive advantage. BMC Digital Enterprise Management is a set of innovative IT solutions designed to make digital business fast, seamless, and optimized from mainframe to mo...
SYS-CON Events announced today that MobiDev will exhibit at SYS-CON's 18th International Cloud Expo®, which will take place on June 7-9, 2016, at the Javits Center in New York City, NY. MobiDev is a software company that develops and delivers turn-key mobile apps, websites, web services, and complex software systems for startups and enterprises. Since 2009 it has grown from a small group of passionate engineers and business managers to a full-scale mobile software company with over 200 develope...
As cloud and storage projections continue to rise, the number of organizations moving to the cloud is escalating and it is clear cloud storage is here to stay. However, is it secure? Data is the lifeblood for government entities, countries, cloud service providers and enterprises alike and losing or exposing that data can have disastrous results. There are new concepts for data storage on the horizon that will deliver secure solutions for storing and moving sensitive data around the world. ...
SoftLayer operates a global cloud infrastructure platform built for Internet scale. With a global footprint of data centers and network points of presence, SoftLayer provides infrastructure as a service to leading-edge customers ranging from Web startups to global enterprises. SoftLayer's modular architecture, full-featured API, and sophisticated automation provide unparalleled performance and control. Its flexible unified platform seamlessly spans physical and virtual devices linked via a world...
SYS-CON Events announced today that ContentMX, the marketing technology and services company with a singular mission to increase engagement and drive more conversations for enterprise, channel and SMB technology marketers, has been named “Sponsor & Exhibitor Lounge Sponsor” of SYS-CON's 18th Cloud Expo, which will take place on June 7-9, 2016, at the Javits Center in New York City, New York. “CloudExpo is a great opportunity to start a conversation with new prospects, but what happens after the...
Companies can harness IoT and predictive analytics to sustain business continuity; predict and manage site performance during emergencies; minimize expensive reactive maintenance; and forecast equipment and maintenance budgets and expenditures. Providing cost-effective, uninterrupted service is challenging, particularly for organizations with geographically dispersed operations.
The IoTs will challenge the status quo of how IT and development organizations operate. Or will it? Certainly the fog layer of IoT requires special insights about data ontology, security and transactional integrity. But the developmental challenges are the same: People, Process and Platform. In his session at @ThingsExpo, Craig Sproule, CEO of Metavine, will demonstrate how to move beyond today's coding paradigm and share the must-have mindsets for removing complexity from the development proc...
SYS-CON Events announced today TechTarget has been named “Media Sponsor” of SYS-CON's 18th International Cloud Expo, which will take place on June 7–9, 2016, at the Javits Center in New York City, NY, and the 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. TechTarget is the Web’s leading destination for serious technology buyers researching and making enterprise technology decisions. Its extensive global networ...
SYS-CON Events announced today that Commvault, a global leader in enterprise data protection and information management, has been named “Bronze Sponsor” of SYS-CON's 18th International Cloud Expo, which will take place on June 7–9, 2016, at the Javits Center in New York City, NY, and the 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. Commvault is a leading provider of data protection and information management...
The essence of data analysis involves setting up data pipelines that consist of several operations that are chained together – starting from data collection, data quality checks, data integration, data analysis and data visualization (including the setting up of interaction paths in that visualization). In our opinion, the challenges stem from the technology diversity at each stage of the data pipeline as well as the lack of process around the analysis.
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, wh...
Designing IoT applications is complex, but deploying them in a scalable fashion is even more complex. A scalable, API first IaaS cloud is a good start, but in order to understand the various components specific to deploying IoT applications, one needs to understand the architecture of these applications and figure out how to scale these components independently. In his session at @ThingsExpo, Nara Rajagopalan is CEO of Accelerite, will discuss the fundamental architecture of IoT applications, ...
SYS-CON Events announced today that Tintri Inc., a leading producer of VM-aware storage (VAS) for virtualization and cloud environments, will exhibit at the 18th International CloudExpo®, which will take place on June 7-9, 2016, at the Javits Center in New York City, New York, and the 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA.
SYS-CON Events announced today that MangoApps will exhibit at SYS-CON's 18th International Cloud Expo®, which will take place on June 7-9, 2016, at the Javits Center in New York City, NY. MangoApps provides modern company intranets and team collaboration software, allowing workers to stay connected and productive from anywhere in the world and from any device. For more information, please visit https://www.mangoapps.com/.
SYS-CON Events announced today that Alert Logic, Inc., the leading provider of Security-as-a-Service solutions for the cloud, will exhibit at SYS-CON's 18th International Cloud Expo®, which will take place on June 7-9, 2016, at the Javits Center in New York City, NY. Alert Logic, Inc., provides Security-as-a-Service for on-premises, cloud, and hybrid infrastructures, delivering deep security insight and continuous protection for customers at a lower cost than traditional security solutions. Ful...
In his session at 18th Cloud Expo, Bruce Swann, Senior Product Marketing Manager at Adobe, will discuss how the Adobe Marketing Cloud can help marketers embrace opportunities for personalized, relevant and real-time customer engagement across offline (direct mail, point of sale, call center) and digital (email, website, SMS, mobile apps, social networks, connected objects). Bruce Swann has more than 15 years of experience working with digital marketing disciplines like web analytics, social med...
SYS-CON Events announced today Object Management Group® has been named “Media Sponsor” of SYS-CON's 18th International Cloud Expo, which will take place on June 7–9, 2016, at the Javits Center in New York City, NY, and the 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA.
SYS-CON Events announced today that EastBanc Technologies will exhibit at SYS-CON's 18th International Cloud Expo®, which will take place on June 7-9, 2016, at the Javits Center in New York City, NY. EastBanc Technologies has been working at the frontier of technology since 1999. Today, the firm provides full-lifecycle software development delivering flexible technology solutions that seamlessly integrate with existing systems – whether on premise or cloud. EastBanc Technologies partners with p...
WebRTC is bringing significant change to the communications landscape that will bridge the worlds of web and telephony, making the Internet the new standard for communications. Cloud9 took the road less traveled and used WebRTC to create a downloadable enterprise-grade communications platform that is changing the communication dynamic in the financial sector. In his session at @ThingsExpo, Leo Papadopoulos, CTO of Cloud9, will discuss the importance of WebRTC and how it enables companies to fo...
The IoT is changing the way enterprises conduct business. In his session at @ThingsExpo, Eric Hoffman, Vice President at EastBanc Technologies, discuss how businesses can gain an edge over competitors by empowering consumers to take control through IoT. We'll cite examples such as a Washington, D.C.-based sports club that leveraged IoT and the cloud to develop a comprehensive booking system. He'll also highlight how IoT can revitalize and restore outdated business models, making them profitable...