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Cliff Click nailed the whole Java vs C/C++ performance subject in one terrific post - http://www.azulsystems.com/blog/cliff-click/2009-09-06-java-vs-c-performan

Cliff Click nailed the whole Java vs C/C++ performance subject in one terrific post - http://www.azulsystems.com/blog/cliff-click/2009-09-06-java-vs-c-performanceagain http://www.azulsystems.com/blog/cliff-click/2009-09-06-java-... . Seriously no further discussion is needed on this topic until even more significant performance advances are made either in C/C++ compilers or the JVM :)

rm445 16y ago
That's a fascinating article, and you may be right that little more need be said, but the author wanders WAY off the subject when he gets to the benefits of Java. Claiming that you can use the time saved by having garbage collection to make your program more efficient in other ways does not make a convincing argument when you're discussing fine points of performance. In case that wasn't clear, he claims not that garbage collection is more efficient, but the saved programmer time can be used in some hand-waving way to improve efficiency. Likewise he wanders off into wooly territory with the claim that very large Java programs can be written more quickly. These would be perfectly fine if he were posting the reasons he thinks Java is better, but in a technical discussion of all-out performance it's just offtopic.
- blinkingled 16y ago
  Strictly speaking, what you say is true, but practically those are significant and relevant benefits of Java. Considering that performance is always a trade-off with price - if you think about price/performance ratio - the ability to write programs quickly is of relevance.
pkaler 16y ago
That article is naive. It assumes that C/C++ developers concerned with performance write object-oriented code. They do not. They write data-oriented code. Most of the multi-threading issues go away. This is how fast code is written for the Cell processor in the Sony PS3. Most malloc/free issues go away. Most data is a value type or has an explicit lifetime (game-lifetime, mission-lifetime, frame-lifetime for the game development case). More information on data-oriented design: http://gamesfromwithin.com/data-oriented-design http://gamesfromwithin.com/data-oriented-design
- blinkingled 16y ago
  I didn't read through the link fully but it sounds to me like after changing the way you program you can get C++ to deliver the kind of performance a JVM gives you without doing anything special? Or are you saying with data-oriented programming C++ becomes significantly faster than Java? To the extent that most people aren't going to change their programming methodology just to avoid Java and C++ still has its niche usages - I don't think the article is naive in any way.
  - pkaler 16y ago
    Data-oriented programming produces programs that are a magnitude faster than object-oriented programs. It's the same difference as stateful vs stateless code. And it's the same difference as RESTful APIs vs RPC. If you care about performance and scalability then you write stateless code and use RESTful interfaces. You also choose to write data-oriented code rather than object-oriented code. Data-oriented code is not possible in Java because you can't create complex value types and you can't control when and where memory gets allocated and deallocated.
    - repsilat 16y ago
      > Data-oriented code is not possible in Java... There are obviously techniques in data-oriented code that aren't possible in Java, but a lot of the key insight is applicable in just about every language. Structures-of-arrays, defining the data in objects based on usage patterns instead of responsibilities and "model-the-world" categorisation... Java doesn't have a `sizeof` operator, and objects probably don't tend to store their object member variables by value, and it's not always obvious which function calls cost how much... Problems, to be sure, but if you really want data-oriented code you can usually contort yourself far enough to get it.

rm445 16y ago

That's a fascinating article, and you may be right that little more need be said, but the author wanders WAY off the subject when he gets to the benefits of Java. Claiming that you can use the time saved by having garbage collection to make your program more efficient in other ways does not make a convincing argument when you're discussing fine points of performance. In case that wasn't clear, he claims not that garbage collection is more efficient, but the saved programmer time can be used in some hand-waving way to improve efficiency. Likewise he wanders off into wooly territory with the claim that very large Java programs can be written more quickly. These would be perfectly fine if he were posting the reasons he thinks Java is better, but in a technical discussion of all-out performance it's just offtopic.

blinkingled 16y ago
Strictly speaking, what you say is true, but practically those are significant and relevant benefits of Java. Considering that performance is always a trade-off with price - if you think about price/performance ratio - the ability to write programs quickly is of relevance.

pkaler 16y ago

That article is naive. It assumes that C/C++ developers concerned with performance write object-oriented code. They do not. They write data-oriented code. Most of the multi-threading issues go away. This is how fast code is written for the Cell processor in the Sony PS3. Most malloc/free issues go away. Most data is a value type or has an explicit lifetime (game-lifetime, mission-lifetime, frame-lifetime for the game development case). More information on data-oriented design: http://gamesfromwithin.com/data-oriented-design http://gamesfromwithin.com/data-oriented-design

blinkingled 16y ago
I didn't read through the link fully but it sounds to me like after changing the way you program you can get C++ to deliver the kind of performance a JVM gives you without doing anything special? Or are you saying with data-oriented programming C++ becomes significantly faster than Java? To the extent that most people aren't going to change their programming methodology just to avoid Java and C++ still has its niche usages - I don't think the article is naive in any way.
- pkaler 16y ago
  Data-oriented programming produces programs that are a magnitude faster than object-oriented programs. It's the same difference as stateful vs stateless code. And it's the same difference as RESTful APIs vs RPC. If you care about performance and scalability then you write stateless code and use RESTful interfaces. You also choose to write data-oriented code rather than object-oriented code. Data-oriented code is not possible in Java because you can't create complex value types and you can't control when and where memory gets allocated and deallocated.
  - repsilat 16y ago
    > Data-oriented code is not possible in Java... There are obviously techniques in data-oriented code that aren't possible in Java, but a lot of the key insight is applicable in just about every language. Structures-of-arrays, defining the data in objects based on usage patterns instead of responsibilities and "model-the-world" categorisation... Java doesn't have a `sizeof` operator, and objects probably don't tend to store their object member variables by value, and it's not always obvious which function calls cost how much... Problems, to be sure, but if you really want data-oriented code you can usually contort yourself far enough to get it.