5 ms·

I hear that argument a lot, and yet I have never seen real-life software that runs comparably in Java and C++. For example, a few weeks ago, I was looking at so

by gcv 12y ago

I hear that argument a lot, and yet I have never seen real-life software that runs comparably in Java and C++. For example, a few weeks ago, I was looking at some (fairly simple) data processing code backed by SQLite. The Java version was too slow for the amount of data that needed to get analyzed and reanalyzed repeatedly. A rewrite in C++, with no special trickery, ran 3x faster. After isolating everything in Java (including ditching the JDBC driver for lower-level SQLite bindings), nothing changed. It was likely JNI overhead, but frankly, that doesn't matter: Java was too slow. No sophisticated benchmarks here — just real-life production code that runs like molasses in the JVM and runs acceptably in C++. Also, C++11 is not a low-level language anymore. (And I say this as a long-time Lisp and Clojure programmer.)

technomancy 12y ago
I think the point is that claiming speed is a property of languages is simply a category error, like saying programming languages are green or noisy. These can be properties of programs (well, properties of a given execution of a program) but have nothing to do with languages.
- gcv 12y ago
  For languages with exactly one useable implementation, the distinction is rather academic. In the case of C++, as far as I know, every production-quality compiler produces code which runs circles around code produced by any Java compiler. In addition, some languages have features which cause them to be more difficult to optimize. (See, e.g., the restrict keyword in C99.)
  - Pacabel 12y ago
    That has been my experience, as well. It's also important to remember that Java is still in this position even after almost 20 years of development. And this is development undertaken by large companies that were or are quite well funded, and have had very talented individuals work on this technology. If they've yet to get consistent C++-level performance out of Java or the JVM, it's most likely factors inherent to those technologies that are to blame.

by gcv 12y ago

technomancy 12y ago

I think the point is that claiming speed is a property of languages is simply a category error, like saying programming languages are green or noisy. These can be properties of programs (well, properties of a given execution of a program) but have nothing to do with languages.

gcv 12y ago
For languages with exactly one useable implementation, the distinction is rather academic. In the case of C++, as far as I know, every production-quality compiler produces code which runs circles around code produced by any Java compiler. In addition, some languages have features which cause them to be more difficult to optimize. (See, e.g., the restrict keyword in C99.)
- Pacabel 12y ago
  That has been my experience, as well. It's also important to remember that Java is still in this position even after almost 20 years of development. And this is development undertaken by large companies that were or are quite well funded, and have had very talented individuals work on this technology. If they've yet to get consistent C++-level performance out of Java or the JVM, it's most likely factors inherent to those technologies that are to blame.