possible threading problem

[Daniel Fisher]

On Wed, 02 Jun 2004 21:42:59 +0200
Ronald Klop <ronald at cs.vu.nl> wrote:

> On Wed, 2 Jun 2004 09:52:45 -0400, Daniel Fisher <daniel.fisher at vt.edu>  
> wrote:
> 
> > On Wed, 02 Jun 2004 10:04:38 +0300
> > Panagiotis Astithas <past at noc.ntua.gr> wrote:
> >
> >> Daniel Fisher wrote:
> >> > I'm experiencing a weird threading problem with jdk-1.4.2p6_3 that I  
> >> don't
> >> > see on Linux.
> >> > It looks like the BSD JDK is not honoring sychronize statements.
> >> > Has anyone seen this before?
> >> > If not, who should I send sample code to?
> >>
> >> Um, the list?
> >> --
> >> Panagiotis Astithas
> >
> > Alrighty then....
> > attached is a tarball with the sample classes in it.
> > Untar and cd into the directory.
> > Execute: java -jar prop.jar
> > These classes monitor the main.properties file and echo the changes to  
> > stdout.
> > Edit main.properties while the java job is running.
> > FreeBSD JVM throws an InterruptedIOException, Linux JVM does not throw an
> > exception.
> 
> Add debugging like, so you can make sure synchronized is (not) working.
> synchronized (a) {
> 	System.out.println("In a 1");
> 	...
> 	System.out.println("Out a 1");
> }
> 
> If I recompile your program I get other results after modifying the  
> properties file.
> java.lang.NoClassDefFoundError: prop/PropEvent
>          at prop.PropSingleton.removeProperties(PropSingleton.java:74)
>          at prop.PropMonitor.run(PropMonitor.java:71)
>          at java.lang.Thread.run(Thread.java:534)
> 
> PropMonitor interrupts itself. Why? it's useless.
> By the way if you don't do this your program works.
> 
> Offtopic:
> In PropMonitor you catch Exception. So you will mis all other possible  
> error messages from java.
> If this is not just a test class I would rewrite it.
> Why this:
> try {
> 	throw Exception();
> } catch (Exception) {
> 	break;
> }
> 
> You can also just do break in stead of the exception.
> And you can remove all the interrupt/interrupted calls. Only keep the  
> boolean run.
> And even nicer than the break is setting run = false to end the while.
> 
> But only removing the stopMonitor call from PropMonitor.run() will also  
> make it work. :-)
> 
> Ronald.
> 

I think you've missed the point.
The question is, why does the BSD JVM behave differently and does it need
fixing?

-- 
Daniel Fisher