i saw the bug you have opened, the behavior is pretty interesting, which is out
of my expectation. thank you for the information.
.Hzj_jie
> Subject: Re: [Mono-dev] a set of tests to find out the difference between
> .Net and Mono implementation
> From: jonpr...@vt.edu
> Date: Tue, 16 Sep 2014 12:31:37 -0400
> CC: mono-devel-list@lists.ximian.com
> To: hzj_...@hotmail.com
>
> On Sep 16, 2014, at 6:10 AM, 何子杰Hzj_jie <hzj_...@hotmail.com> wrote:
> > 1. GC
> > thought GC.Collect() does not guarantee all the inaccessible objects are
> > finalized and reclaimed, .Net implementation usually be able to delete all
> > the inaccessible objects.
> > impacts, delegate_pinning_test, it make sure the delegate / event in .net
> > will release the object after itself has been released.
> > weak_pointer_test, weak_pointer is a simple wrapper of WeakReference, which
> > is strong-typed.
> > event_disposer_test, event_disposer is a strong-typed pointer, which
> > provide disposing event when disposing.
> > lifetime_binder_test, lifetime_binder is a collection to avoid the object
> > to be finalized.
>
> Developers need to write tests for finalizers, and writing tests for
> finalizers can be tricky for a variety of reasons. As such, it is quite
> possible that a GC-related test that "works" on .NET won't work on Mono w/o
> change.
>
> If you want to test your class' finalizer, then you need to use two threads +
> WeakReference:
>
> WeakReference r = null;
> var t = new Thread (() => {
> var v = new ClassToTest ();
> r = new WeakReference (t);
> });
> t.Start ();
> t.Join ();
> GC.Collect ();
> GC.WaitForPendingFinalizers ();
>
> // can now [0] check r.IsAlive, etc.
>
> The reason you create the instance + WeakReference on another thread is
> because Mono's GC will *conservatively* scan the thread's heap looking for
> valid references. By using a new thread *which exits*, the conservative stack
> scan will "skip" the exited thread, and thus won't find any valid references
> to the allocated instance. This in turn allows you to use the WeakReference
> to determine if the instance has in fact been collected. (Or not, if your
> ClassToTest registers itself with some static collection or something...)
>
> - Jon
>
> [0]: https://bugzilla.xamarin.com/show_bug.cgi?id=20503
>
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