Object Lifetimes (GC) Event Subscriptions

On 11/15/06, Robert Rolls <robertronetspace.net.au> wrote:
> Does A need to keep B around for the lifetime of A or
as B has registered
> for an event will it live for the duration of A's
existence (i.e., the
> object reference is in the delegate call chain)?

The delegate chain is not implemented as a weakreference
chain,
therefor, the chain MUST keep a *normal* ref to B.

Exactly due to this behaviour, people are *leaking* winforms
instances
in their programs. The instances of winforms (or other
controls) are
kept alive through their event subscribers without notice...

// Ryan

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So is there something I need to do to tell B to undo the
event subscription?

When A is eventually ready for collection the GC won't be
able to reclaim A
because of this reference?
From what you say below eventually there should be a memory
allocation
failure?

Thanks
Rob.

-----Original Message-----
From: Discussion of development on the .NET platform using
any managed
language [mailtoOTNET-CL
RDISCUSS.DEVELOP.COM] On Behalf Of Ryan Heath
Sent: Thursday, November 16, 2006 2:01 AM
To: DOTNET-CLRDISCUSS.DEVELOP.COM
Subject: Re: [DOTNET-CLR] Object Lifetimes (GC) Event
Subscriptions

On 11/15/06, Robert Rolls <robertronetspace.net.au> wrote:
> Does A need to keep B around for the lifetime of A or
as B has
> registered for an event will it live for the duration
of A's existence
> (i.e., the object reference is in the delegate call
chain)?

The delegate chain is not implemented as a weakreference
chain, therefor,
the chain MUST keep a *normal* ref to B.

Exactly due to this behaviour, people are *leaking* winforms
instances in
their programs. The instances of winforms (or other
controls) are kept alive
through their event subscribers without notice...

// Ryan

===================================
This list is hosted by DevelopMentorR  http://www.develop.com

View archives and manage your subscription(s) at http://discuss.develop.com


===================================
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View archives and manage your subscription(s) at http://discuss.develop.com