Name: mc57594 Date: 02/07/97
Please notice that there are TWO sections of code submitted. I included
both here for completeness.
-mark

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Under win32, all static methods are getting a monitor lock rather than just those that are explicitly mark synchronized. The following program gives this output before hanging (correctly) under JDK 1.0.2:

  Should print 'hello'.
  Hello.
  It worked. Program should now hang.

And this output before hanging (incorrectly) under JDK 1.13b:

  Should print 'hello'.

This is not affected by what compiler is used to compile the program, only what VM it is run under.

// file: testlock.java

public class testlock
{
   synchronized static public void shouldHang()
   {
      System.out.println("Didn't hang, it should've.");
   }

   static public void shouldNotHang()
   {
      System.out.println("Hello.");
   }

   static public void main(String args[])
   {
      testlock test = new testlock();
      synchronized (test.getClass())
      {
         new Thread(new trylock()).start();
      }
      System.out.println("Exiting.");
   }
}

class trylock implements Runnable
{
   public void run()
   {
      System.out.println("Should print 'hello'.");
      testlock.shouldNotHang();
      System.out.println("It worked. Program should now hang.");
      testlock.shouldHang();
   }
}

The relevant portion of the trace follows:

Full thread dump:
    "Thread-1" (TID:0xe63098, sys_thread_t:0x77b300, Win32ID:0xfffd83c7, state:MW) prio=5
        trylock.run(testlock.java:31)
        java.lang.Thread.run(Thread.java:336)
    "Finalizer thread" (TID:0xe60180, sys_thread_t:0x774e80, Win32ID:0xfffd974f, state:CW) prio=2
    "main" (TID:0xe60150, sys_thread_t:0x77d8a0, Win32ID:0xfffdadb3, state:R) prio=5
        java.lang.Thread.suspend(Thread.java:443)
        testlock.main(testlock.java:21)
Monitor Cache Dump:
         java.lang.Class@E63078/EAC530 (key=0xe63078): "main"
         java.lang.Class@E630A0/EAC5F0 (key=0xe630a0): "Thread-1"

company - 601 Inc. , email - ###@###.###
======================================================================
From: ###@###.###

Synopsis: Corrected bug report: All static methods treated as if synchronized.
Severity Impact: (internal)
Severity Functionality: (internal)
Priority: (internal)
Description: My previous bug report omitted a line of code crucial to reproducing the problem. Here is the corrected code (note the suspend() call to ensure that the lock is maintained):

public class testlock
{
   synchronized static public void shouldHang()
   {
      System.out.println("Didn't hang, it should've.");
   }

   static public void shouldNotHang()
   {
      System.out.println("Hello.");
   }

   static public void main(String args[])
   {
      testlock test = new testlock();
      synchronized (test.getClass())
      {
         new Thread(new trylock()).start();
         Thread.currentThread().suspend(); // forgot this line
      }
      System.out.println("Exiting.");
   }
}

class trylock implements Runnable
{
   public void run()
   {
      System.out.println("Should print 'hello'.");
      testlock.shouldNotHang();
      System.out.println("It worked. Program should now hang.");
      testlock.shouldHang();
   }
}

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