Description Alexander Veit 2008-05-31 17:00:57 EDT

Build ID: Build id: I20070625-1500

Steps To Reproduce:
The Eclipse compiler reports the problem

"Read access to enclosing field SyntheticAccessorTest.m_iPrivateCnt is emulated by a synthetic accessor method. Increasing its visibility will improve your performance"

As the attached class suggests, there are no performance problems at all since modern (JIT) compilers seem to produce the same optimized code regardless of how the enclosing member is accessed.

So there's no need to force people to violate good OOP practices in favour of gaining performance.

More information:
Use this test program

D:\>java -version
java version "1.6.0_05"
Java(TM) SE Runtime Environment (build 1.6.0_05-b13)
Java HotSpot(TM) Client VM (build 10.0-b19, mixed mode, sharing

javac -g:none performance/SyntheticAccessorTest.java

java performance.SyntheticAccessorTest
 or
java -XX:CompileThreshold=0 performance.SyntheticAccessorTest

- - - - - - - - - - - - - - - - - - - - - - - -
package performance;

public final class SyntheticAccessorTest
{
 private int m_iPrivateCnt;

 protected int m_iProtectedCnt;


 private SyntheticAccessorTest() {}


 public static void main(String[] args)
 {
  new SyntheticAccessorTest().run(1000000);

  Thread.yield();

  long l_lPrivate   = 0L;
  long l_lProtected = 0L;

  for (int i = 0; i < 100; i++)
  {
   final long[] l_result;

   l_result = new SyntheticAccessorTest().run(10000000);

   l_lPrivate   += l_result[0];
   l_lProtected += l_result[1];
  }

  System.out.println("private:   " + (l_lPrivate / 1000) + " us");
  System.out.println("protected: " + (l_lProtected / 1000) + " us");
 }


 private long[] run(final int p_iLoops)
 {
  final long l_lStartPrivate;
  final long l_lEndPrivate;
  final long l_lStartProtected;
  final long l_lEndProtected;

  // private
  m_iPrivateCnt   = 0;
  l_lStartPrivate = System.nanoTime();

  new Runnable()
  {
   @Override
   public void run()
   {
    for (int i = 0; i < p_iLoops; i++)
     m_iPrivateCnt++;
   }
  }.run();

  l_lEndPrivate = System.nanoTime();

  // protected
  m_iProtectedCnt   = 0;
  l_lStartProtected = System.nanoTime();

  new Runnable()
  {
   @Override
   public void run()
   {
    for (int i = 0; i < p_iLoops; i++)
     m_iProtectedCnt++;
   }
  }.run();

  l_lEndProtected = System.nanoTime();
  assert m_iProtectedCnt == p_iLoops;

  return new long[] {l_lEndPrivate - l_lStartPrivate, l_lEndProtected - l_lStartProtected};
 }
}