Re: Efficiency in Java

"sara" <sarasara82@gmail.com> writes:


  Optimization might not be /that/ evil as it sometimes is said.

  After all, some products have as their main problem that they
  are too slow.

  Also, some early design decisions might have a critical impact
  on the speed, so that even early optimization might not be
  that bad.

  However, the problem might be the idea to teach or learn
  optimization in isolation from other aspects of programming,
  Java and computer science.

  If someone is well educated in computer science (e.g.,
  algorithms and complexity), in Java and the JVM and software
  concepts (patterns, paradigms) and tools (like profilers) he
  will also have learnt what makes software slow and what makes
  it fast. He will not need a separate education on the topic.

  However, when someone would try to apply a toolbox of
  speedup-tricks in isolation from other aspects of software
  quality and trade-offs with them, it might have the opposite
  effect or could endager the correctness of the software.

  Additional problems are that tricks or strategies that speed
  up a Java program might slow it down on a later version of the
  JVM or on another JVM than that of Sun Microsystems, Inc.

  An important aspect of runtime efficency might be
  memory-locality, e.g., execution of code that already is in
  the cache of the processor is faster that execution of code
  that needs to be read from RAM. Or the success of branch
  prediction. But the more abstract and high-level the language
  is, the more difficult it might be for the programmer to
  foresee this.

  This might be somewhat out-of-date:

http://www.cybergrain.com/tech/writing/efficient-java.html

  Then there also is

http://java.sun.com/docs/books/effective/

  and

http://java.sun.com/docs/hotspot/PerformanceFAQ.html