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From "Alexey Varlamov" <alexey.v.varla...@gmail.com>
Subject Re: [drlvm] HARMONY-1582 - invocation API for DRLVM CHECKPOINT
Date Fri, 29 Sep 2006 03:50:33 GMT
+1 for commit.
I didn't see any major flaw in the patch; at the same time this
functionality is vital for further progress in many areas. And due to
large scale of the patch it will become stale quite soon.
We certainly should avoid this style in future: need to discuss design
earlier and split changes to smaller chanks when possible. But now I
vote for faster progress.

--
Regards,
Alexey


2006/9/28, Evgueni Brevnov <evgueni.brevnov@gmail.com>:
> I suppose two days silence means that there is no objects (maybe
> interest) against proposed patch. I would suggest to commit it ASAP.
> It really works! There are some cases when current VM crashes but the
> patch fixes it. I can work on bringing cunit tests to live as soon as
> the patch is committed.... This is just my understanding.
>
> Thanks
> Evgueni
>
> On 9/28/06, Geir Magnusson Jr. <geir@pobox.com> wrote:
> > So where are we here?
> >
> > On Sep 28, 2006, at 12:41 AM, Evgueni Brevnov wrote:
> >
> > > On 9/28/06, Weldon Washburn <weldonwjw@gmail.com> wrote:
> > >> On 9/26/06, Evgueni Brevnov <evgueni.brevnov@gmail.com> wrote:
> > >> >
> > >> > On 9/27/06, Andrey Chernyshev <a.y.chernyshev@gmail.com> wrote:
> > >> > > (3)
> > >> > > One more lock is added - hythread_lib_lock. How is that differ
> > >> from
> > >> > > the hythread_global_lock that we already have? Each extra lock
> > >> to the
> > >> > > system may add more possibilities for deadlocks, as well as can
> > >> > > negatively impact the scalability (unless some of the existing
> > >> locks
> > >> > > are split).
> > >> > hythread_lib_lock acquires exactly the same lock as
> > >> > hythread_global_lock. Probably I miss something but we need to be
> > >> > compatible with IBM threading library now. This library has such
> > >> > function. That's why I added it. Sounds right?
> > >>
> > >>
> > >> Well,  this sort of, kind of sounds right but not quite.  Its a
> > >> little more
> > >> subtle than being compatible with IBM threading library.  The
> > >> first goal is
> > >> to identify the parts of IBM threading library that are JVM
> > >> independent.  It
> > >> makes sense for DRLVM to be compatible with the independent
> > >> parts.   This
> > >> should be a nobrainer.
> > >>
> > >> The parts of IBM threading library that assume a specific JVM
> > >> implementation
> > >> will be a problem.  We will need to find a solution that is
> > >> endorsed by all
> > >> the stakeholders (including J9 folks).  The hythread_global_lock
> > >> falls into
> > >> this category.  For starts, I would like to see a concise
> > >> description from
> > >> the portlib owners on what hythread_global_lock protects, which
> > >> locks have
> > >> to be held before grabbing this lock, are there any restrictions
> > >> on what
> > >> system calls can be made while holding this lock (like sleep or
> > >> wait), etc.
> > >
> > > Weldon, I completely agree with what your are saying. It's common
> > > problem of current hythread that should be resolved some how. I just
> > > go inline with current implementation and added two missing functions.
> > > Missing these can lead to the same problems as with hythread_exit
> > > discussed  in another thread "[drlvm] [launcher] Executable hangs".
> > >
> > >>
> > >> To get a better idea what's in the patch.diff, I printed it out.
> > >> Its 120+
> > >> pages.  Quite a big patch!  Most of it looks like straight forward
> > >> JNI
> > >> interface glue.  There are some tricky parts.  I would like to
> > >> know the
> > >> design review process for these parts.  Using grep, I found 20
> > >> locations
> > >> where ...suspend_enable... and ...suspend_disable... have been
> > >> added.  And
> > >> 25 locations where enable/disable have been removed.  Failure in
> > >> this logic
> > >> can lead to incorrect reference pointer enumeration.  These are
> > >> probably the
> > >> hardest bugs to find.  Please tell us who has looked at this code
> > >> in depth.
> > > Only me and you :-) Honetsly I think it happpens now....
> > >
> > >> Are there any known design flaws in it?
> > > I can think of two possible problems we may want to discuss.
> > > 1) Should native threads have "daemon" status or its completely java
> > > notion? This is TM related thing.
> > > 2) Should we attach thread to VM before attaching it to TM by calling
> > > jthread_atatch OR jthread_attach should callback VM to attach a thread
> > > to it? I didn't change original design of TM here ...... it implements
> > > second choice.
> > >
> > >>
> > >> I also notice APIs called tmn_suspend_enable(),
> > >> hythread_suspend_enable()
> > >> -- are these simply different names for the same binary
> > >> executible.  Or
> > >> different binaries that do the same thing??
> > >
> > > No, this is not just different names. tm_suspend_enable asserts that
> > > thread is in disabled state before calling hythread_suspend_enable (in
> > > debug mode only).
> > >
> > > Thanks
> > > Evgueni
> > >>
> > >>
> > >> --
> > >> > Weldon Washburn
> > >> > Intel Middleware Products Division
> > >>
> > >>
> > >
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