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From "Weldon Washburn" <weldon...@gmail.com>
Subject Re: [drlvm][threading] taking a closer look at Harmony-2803 (stress.Mix hangs on rhel4)
Date Fri, 05 Jan 2007 21:09:16 GMT
Rana,

Can you try MegaSpawn.java that I attached to harmony-2803?  Its basically a
version of stress.Mix with all the non-essential stuff removed.  I would
like to know if it faithfully reproduces the bug(s) in your environment.  It
would be great if this is indeed true since we would have a simple test that
always breaks the jvm.  This makes for much easier debug.

I also see what you observe below.  I also like the idea of killing the
"occupy" thread.  It seems there might be some notion of memory quota --
something for which I have been waiting a long time.

>From the below, the hang is observed on both winxp and linux.  If this is
correct, we can focus on the OS independent code  :)



On 1/5/07, Rana Dasgupta <rdasgupt@gmail.com> wrote:
>
> HI Weldon,
>   On a 2 cpu smp RHEL4 box:
>     - on RI the modified test always passes
>     - DRLVM always fails with OOME when trying to spawn threads
>
> On a 2 cpu XP box:
>    - RI kills the "occupy" thread( I thought this is really smart ), but
> passes
>   - DRLVM sometimes passes, sometimes hangs, occassionally reports invalid
> memory references, VM launcher errors etc. etc.
>
>
> Rana
>
> On 1/5/07, Weldon Washburn <weldonwjw@gmail.com> wrote:
> >
> > All,
> >
> > An update.  I think I can cause the bug(s) we are discussing in this
> email
> > chain to surface 100% of the time on 2 cpu rhel4.  Hacking stress.Mixsuch
> > that it only runs the "spawn" method seems to do it.   This hack always
> > fails on 2 cpu rhel4 and never fails on 1 cpu winxp.  It would be
> > interesting to try on 1 cpu rhel4 and 2 cpu winxp.  If anyone has this
> > combination, please try it.  This would tell us if the bug is sensitive
> to
> > OS.
> >
> > When I run the below patch on RI, it completes successfully every time.
> > Curiously it looks like the RI kills the "occupy" thread.  It prints on
> > the
> > console output, "occupy terminated by java.lang.OutOfMemoryError..
> .".  But
> > I
> > don't see occupy terminate when running drlvm.  I will run more
> > tests.  This
> > may actually be compounding the problems we are seeing.
> >
> > Naveen, Rana,
> > Can you try the below patch on your hardware to see if you can reproduce
> > what I describe above?  Does the output look the same as Harmony-2803?
> >
> >
> > Below is an svn diff that makes the hard failure happen on 2 cpu rhel4:
> >
> > Index: Mix.java
> > ===================================================================
> > --- Mix.java    (revision 491852)
> > +++ Mix.java    (working copy)
> > @@ -93,6 +93,8 @@
> >
> >     static Random random = new Random(0);
> >     static String selectThreadType(int i) {
> > +               return "spawn";
> > +               /*
> >         switch (i % 9) {
> >             case 0: return "uncontended";
> >             case 1: return "contended";
> > @@ -105,6 +107,7 @@
> >             case 8: return "exceptions";
> >         }
> >         return "nothing";
> > +               */
> >     }
> >
> >     static int thread_number = 60;
> >
> >
> >
> > On 1/4/07, Naveen Neelakantam <neelakan@uiuc.edu> wrote:
> > >
> > >
> > > On Jan 4, 2007, at 4:28 PM, Weldon Washburn wrote:
> > >
> > > > I see it hang consistently when running automated mode (build
> > > > test).  I have
> > > > seen it hang once when running manually from a linux terminal
> > > > window.  It
> > > > actually printed out "PASSED" then hung.  This leads me to suspect
> > > > there
> > > > might be problems with how System.out.flush() is working when there
> > > > are
> > > > multiple threads running on SMP.  Are you running on an SMP box?
> > > > Can you
> > > > give me the exact command line you are using?  I would like to try
> > > > it on my
> > > > box.
> > >
> > > Ok, cool.  I was seeing the exact same behavior (i.e. the test prints
> > > PASSED and then hangs).  So it sounds like you are on the right
> > > track, to me anyway.
> > >
> > > But to answer your questions: I am running RHEL4 update 4 on a core2
> > > duo.  The command line I am using is "java -cp . stress.Mix" (with my
> > > path and JAVA_HOME set appropriately).
> > >
> > > Naveen
> > >
> >
> >
> >
> > --
> > Weldon Washburn
> > Intel Enterprise Solutions Software Division
> >
> >
>
>


-- 
Weldon Washburn
Intel Enterprise Solutions Software Division

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