ThreadTest17

Sources

Java Source

Pthread C source

Brief Description

class Obj {
  int count = 0;
  Semaphore semaphore = new Semaphore(1);

  void inc() throws InterruptedException {
    semaphore.require();
    doInc();
    semaphore.provide();
  }

  synchronized void turn() throws InterruptedException {
    waitForTurn();
    doInc();
    giveUpTurn();
  }

  synchronized void doInc() {
    ++count;
  }

  // ...
}

Results

Machine        1-CPU Ultra-1  2-CPU Ultra-2  6-CPU SS1000

JDK1.2b2/green

No sharing           8002         6338         10275  
All sharing          8222         6182         10334
Taking turns        28490        22718  

JDK1.2b2/native

No sharing           8060         3715          7119
All sharing        116881       183272        521828
Taking turns       147872       175356   

SunSoft1.1.4b/native

No sharing                       36885
All sharing                     191940
Taking turns                    156206

Pthreads (CL = 1)

No sharing           3406         2701          3800
All sharing          3435         2684          3787

PThreads (CL = 2)

No sharing           3409         2016          3934
All sharing         43777       108000        267686

    

• 64 threads
• 1048576 total iterations.
• Times are in milliseconds. They include start-up and join times.
• CL is the argument to thr_setconcurrency.
• "Sun1.1.4b" is the SunSoft 1.1.4 beta (of approx 20 december 1997) with JIT.
• The pthread C code is as close to the java code as seems necessary. I haven't implemented the turn-taking code in pthreads yet though. (Writing the pthreads code made me remember just how disgusting it used to be to write MT code in the bad old days.)
• Machines were lightly loaded, but not idle
• The two ultras run Solaris 2.6. The SS1000 runs 2.5.1 with the standard thread patches needed for java native threads.
• "No sharing" means that each thread only accessed a different object's inc method.
• "All sharing" means that all threads accessed the same object's inc method.
• "Taking turns" means that all threads accessed a different object's turn method, which circularly passed the turn around the threads (as in cyclic token-passing).
• Sorry for the other missing cells.

Here are some additional results for NT contributed by David Holmes.

NT4 on a Pentium Pro 180:

Microsoft JVM Build 4.79.2339
  No sharing:   time =   968ms (923ns per iteration)
  All sharing:  time =   953ms (908ns per iteration)
  Taking turns: time = 34703ms (33095ns per iteration)

JDK 1.2 Beta 2
  No sharing:   time =  8687ms (8284ns per iteration)
  All sharing:  time = 77078ms (73507ns per iteration)
  Taking turns: time = 65078ms (62063ns per iteration)

JDK 1.1.5
  No sharing:   time =  4656ms (4440ns per iteration)
  All sharing:  time =  4641ms (4426ns per iteration)
  Taking turns: time = 52750ms (50306ns per iteration)