RFR(S): 8194482: Fix SIGSEGV in print_threads_compiling.

[Lindenmaier, Goetz]

Hi Vladimir, 

thanks for reviewing and sponsoring this change!  

Best regards,
  Goetz.

> -----Original Message-----
> From: hotspot-compiler-dev [mailto:hotspot-compiler-dev-
> bounces at openjdk.java.net] On Behalf Of Vladimir Kozlov
> Sent: Mittwoch, 3. Januar 2018 23:42
> To: hotspot-compiler-dev at openjdk.java.net
> Subject: Re: RFR(S): 8194482: Fix SIGSEGV in print_threads_compiling.
> 
> Looks good.
> 
> I will sponsor it and push into JDK 10.
> 
> Thanks,
> Vladimir
> 
> On 1/3/18 4:37 AM, Lindenmaier, Goetz wrote:
> > Hi,
> >
> > print_threads_compiling prints the tasks compiler threads are working on.
> > It gets the task from the thread, checks it for NULL, and then reads the task
> again from the
> > thread. in the meantime, the compiler thread can set the task back to
> > NULL so that the check was pointless.
> >
> > The task must be read only once.  The field _task must be volatile, so that
> > the C-compiler can't re-introduce the read.
> >
> > Please review this change. I please need a sponsor. I think this should be
> fixed
> > in 10.
> > http://cr.openjdk.java.net/~goetz/wr18/8194482-
> fixPrintCompThr/webrev.01/
> >
> > Best regards,
> >    Goetz.
> >