When running a simple swing application (Prova) on a Solaris7 (TrueColor) which updates some JLabel at a frequency of 20Hz (while loop with Thread.sleep(50)) CPU is really busy (99% or 75% in user time).
The CPU usage is better if the same application is written with awt only.
A similar application in C++ Motif uses only 10% CPU
See the following results:

   Configuration | vmstat (us+sy)| ps -aux (%CPU)
======================================================================
  Solaris_JDK_1.2.1_04 + swing | 99 + 1 = 100 | 70.9
----------------------------------------------------------------------
  Solaris_JDK_1.2.1_04 + awt | 48 + 9 = 57 | 35.7
----------------------------------------------------------------------
Solaris_JDK_1.2.2_05 + swing | 75 + 0 = 75 | 66.1
----------------------------------------------------------------------
Solaris_JDK_1.2.2_05 + awt | 29 + 5 = 34 | 23.2
----------------------------------------------------------------------
 Reference 1.3beta-O + HotSpot + swing | 100 + 0 = 100 | 71.5
----------------------------------------------------------------------
  Solaris_JDK_1.1.8_09a + swing 1.0.3 | 97 + 3 = 100 | 57.1
----------------------------------------------------------------------
  Solaris_JDK_1.1.8_09a + awt | 27 + 1 = 28 | 18.0
----------------------------------------------------------------------
Motif (CC 5.0) | 10 + 2 = 12 | 6.6
----------------------------------------------------------------------

The test swing uses: Prova.class, ProvaT.class, ProvaTmmi.class
The test awt uses: ProvaAwt.class, ProvaAwtT.class, ProvaAwtTmmi.class

This is the while loop with sleep and setText:

    public void run(){
ProvaTmmi mmi = new ProvaTmmi();
mmi.setVisible(true);
System.out.println("setVisible");

double val = 10000;
String Str = new String();
int i, j;
try{
while (true){
// 50=20Hz, 500=2Hz, 5000=.2Hz
sleep(50);
val+=1;
Str = String.valueOf(val);
for (i = 0; i < 7; i++)
for (j = 0; j < 7; j++)
// System.out.println(Str); // OK
mmi.Labels[i][j].setText(Str); // CPU 100%!
mmi.repaint(); // IDEM with or without
}
}
catch(InterruptedException e){};
    }

The Motif application has been built with:
CC -mt -xO4 -xtarget=native -lrt -lpthread -lXm -lXt -lX11 Color.cpp MotifSim.cpp Thread.cpp -o MotifSim

This is the code of the while loop:

MotifSim.cpp:
...
void *Update(void *ThArgs)
{
  char str[20];
  XmString xmstring;
  Arg ArgLabel;
  double val = 10000;
  int i,j;
  Display *pDisplay;
  char* DisplayName = NULL;
  struct timespec TimeStruct;
  // Connect to X server
  pDisplay = XOpenDisplay(DisplayName);
   TimeStruct.tv_sec = 1;
   TimeStruct.tv_nsec = 0;
   nanosleep(&TimeStruct, NULL);
   TimeStruct.tv_sec = 0;
   TimeStruct.tv_nsec = 50000000;
  while (true)
    {
      val+=1;
      for (i=0;i<7;i++)
{
for (j=0;j<7;j++)
{
sprintf(str,"%10.2f",val);
xmstring = XmStringCreate(str, XmSTRING_DEFAULT_CHARSET);
XtSetArg(ArgLabel,XmNlabelString,xmstring);
XtSetValues(Labels[i][j],&ArgLabel,1);
XmStringFree(xmstring);
}
}
      XFlush(pDisplay);
      nanosleep(&TimeStruct, NULL);
    }
  return (NULL);
}


No output running hprof even if I java application has been built with -g (-verbose):
Solaris_JDK_1.2.2_05/bin/java -Xrunhprof:cpu=samples,file=log.txt,depth=3 Prova

The customer needs with java2 and swing a maximum CPU usage of 15% at 20Hz (sleep(50)) because of others real-time applications running in the mean-time

claudio.massi@italy 2000-01-18
In attachment 1.2 source and scripts (Swing-Awt-Motif.tar) and 1.1.8 source and script (Swing-Awt-1.1.8.tar)