Amir Shitrit <AmirShitrit@discussions.microsoft.com> wrote:
> In what cases is it possible that the GC will collect an object while a
> member of that object is still running?

> Could it happen when I create an object without referencing it and then
> invoking one of its members?
> For example: (new Instance()).Invoke(); // there's no reference to the
> Instance object.

> Hi.
> In what cases is it possible that the GC will collect an object while a
> member of that object is still running?

> Could it happen when I create an object without referencing it and then
> invoking one of its members?

> For example: (new Instance()).Invoke(); // there's no reference to the
> Instance object.

Chitrsen wrote:

> 1. GC will not recollect the memory assigned to running object.

> 2. if you open IL of code '(new Instance()).Invoke();', you can see clr
> gives a random generated name for this instance. use ildasm.exe to verify it.

> I hope this answers your question

"Jon Skeet [C# MVP]" <skeet@pobox.com> wrote in message
news:MPG.20b8326cc9c8494d128@msnews.microsoft.com...
> Chitrsen <Chitrsen@discussions.microsoft.com> wrote:
>> 1. GC will not recollect the memory assigned to running object.
>
> Yes it can.
>
>> 2. if you open IL of code '(new Instance()).Invoke();', you can see clr
>> gives a random generated name for this instance. use ildasm.exe to
>> verify it.
>
> It can still be garbage collected before Invoke() has finished
> executing. Here's an example:
>
> using System;
> using System.Threading;
>
> class Test
> {
> ~Test()
> {
> Console.WriteLine ("Finalizer");
> }
>
> void Invoke()
> {
> Console.WriteLine ("Start of method");
> GC.Collect();
> GC.WaitForPendingFinalizers();
>
> Console.WriteLine ("Called GC");
>
> Thread.Sleep(1000);
> Console.WriteLine ("End of method");
> }
>
>
> static void Main()
> {
> new Test().Invoke();
> }
> }
>
> On my box that prints:
> Start of method
> Finalizer
> Called GC
> End of method
>
> --
> Jon Skeet - <skeet@pobox.com>
> http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet
> If replying to the group, please do not mail me too

"Jon Skeet [C# MVP]" <skeet@pobox.com> wrote
> Chris Mullins [MVP] <cmullins@yahoo.com> wrote:

>> I'll have to save that one off as an Interview question one day. "What
>> will
>> this print out?"
>
> I wouldn't use these as interview questions to see whether the
> candidate knows the answer. They are, however, quite good questions to
> see how *interested* the candidate is in little bits of obscure
> knowledge.

Chitrsen <Chitrsen@discussions.microsoft.com> wrote:
> 1. GC will not recollect the memory assigned to running object.

> 2. if you open IL of code '(new Instance()).Invoke();', you can see clr
> gives a random generated name for this instance. use ildasm.exe to verify it.

Chris Mullins [MVP] <cmullins@yahoo.com> wrote:
> That's a pretty evil example.
>
> I wouldn't have thought of it...
>
> I'll have to save that one off as an Interview question one day. "What will
> this print out?"

"Barry Kelly" wrote:

> Chitrsen wrote:
>
> > 1. GC will not recollect the memory assigned to running object.
>
> Actually, it can, if the remaining code path in methods of the instance
> don't access the 'this' reference.
>
> > 2. if you open IL of code '(new Instance()).Invoke();', you can see clr
> > gives a random generated name for this instance. use ildasm.exe to verify it.
>
> This doesn't mean anything. The JIT needs to allocate a register or a
> stack slot and store a reference where the GC can find it, in order to
> prevent collection. If the code doesn't access the reference, the JIT
> compiler can optimize the reference away. The IL is just input to the
> JIT compiler.
>
> > I hope this answers your question
>
> Be careful that your answers are correct!
>
> Check out the following program (compile with 'csc test.cs' if saved to
> test.cs):
>
> ---8<---
> using System;
>
> class C
> {
> ~C()
> {
> Console.WriteLine("Collected!");
> }
>
> static void Main()
> {
> new C().Use();
> }
>
> void Use()
> {
> GC.Collect();
> GC.WaitForPendingFinalizers();
> Console.WriteLine("Used!");
> }
> }
> --->8---
>
> Run it and it results in:
>
> ---8<---
> Collected!
> Used!
> --->8---
>
> -- Barry
>
> --
> http://barrkel.blogspot.com/