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From "Alexey Varlamov" <alexey.v.varla...@gmail.com>
Subject Re: [dlrvm] ClassCircularityError in recursive compilation (Was: Re: [drlvm] smoke test : gc PhantomReferenceQueueTest is really unstable)
Date Thu, 12 Oct 2006 07:38:08 GMT
12.10.06, Pavel Pervov<pmcfirst@gmail.com> написал(а):
> Alexey,
>
> The main issue here is why classloading (?) calls to GC under native lock.
> All the rest is just a consequences.
> Could you, please, show the point (file:line) where gc_alloc is called under
> lock?

Oh, probably you are right. The faulty method is
Java_java_lang_VMClassRegistry_getSystemPackages()
vm\vmcore\src\kernel_classes\native\java_lang_VMClassRegistry.cpp 389-414

Will fix.
--
Alexey

>
> Thanks,
>     Pavel.
>
> On 10/12/06, Alexey Varlamov <alexey.v.varlamov@gmail.com> wrote:
> >
> > Guys,
> >
> > I've found another deadlock scenario recently, see HARMONY-1833 [1]:
> >
> > "deadlocks happening between main thread (MT) and finalizer thread (FT):
> > 1) MT performs classloading, it grabs ClassLoader::_lock;
> > 2) GC happens, FinalizerThread.startFinalization() is called, FT
> > activates;
> > 3) FT invokes some finalize() method, compilation starts and grabs
> > g_compileLock;
> > 4) FT waits for ClassLoader::_lock to allocate code_chunk_info;
> > 5) MT proceeds to compilation of FinalizerThread.spawnBalanceThreads()
> > and waits for g_compileLock;
> >
> > I believe this scenario can be fixed via separating locks for
> > classloading and loader-pool allocations."
> >
> > [1] http://issues.apache.org/jira/browse/HARMONY-1833
> >
> > --
> > Alexey
> >
> > 12.10.06, Gregory Shimansky<gshimansky@gmail.com> написал(а):
> > > On Wednesday 11 October 2006 16:15 Pavel Pervov wrote:
> > > > (Branching from original thread as this is different problem than in
> > the
> > > > root message.)
> > >
> > > Wasn't it the same problem, just happening on classlib initialization? I
> > think
> > > the scenario is the same.
> > >
> > > > The following scenario will fail:
> > > >
> > > > 1) JIT compiles some method and resolves some class "A" through user
> > > > defined class loader
> > > > 2) user define class loader loads class "A" and triggers compilation
> > of
> > > > some of its methods
> > > > 3) this method happens to depend on class "A", and, thus, JIT resolves
> > the
> > > > class "A" through the same class loader
> > > >
> > > > Voila! We have the described situation.
> > >
> > > A synthetic test for drlvm could really help to emphasize the problem.
> > Then we
> > > can run this test on all other VMs with possible modifications. BTW
> > sun's
> > > hotspot should compile a method if it is called several times, so user
> > > defined class loader could do something like calling this method many
> > times
> > > to trigger its compilation.
> > >
> > > --
> > > Gregory Shimansky, Intel Middleware Products Division
> > >
> > > ---------------------------------------------------------------------
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> > >
> >
>
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