FW: [jreed@xxxxxxxxxxxx: Csharp module and memory pressure on GC]

-----Original Message-----
From: Joel Reed [mailto:jreed@xxxxxxxxxxxx]
Sent: 22 September 2004 22:12
To: Fulton, William
Subject: [jreed@xxxxxxxxxxxx: Csharp module and memory pressure on GC]


William, another msg caught by swig's spam traps. Thought you
might be interested since it is C# related.

----- Forwarded message from Joel Reed <jreed@xxxxxxxxxxxx> -----

> From: Joel Reed <jreed@xxxxxxxxxxxx>
> Subject: Csharp module and memory pressure on GC
> 
> This is a complicated issue involving the .Net garbage
> collector, and swigCPtr's.
> 
> Problem: 
> 
> 1) create two c++ classes where 1 class uses
> the facilities of another. eg:
> 
> class o_dbc {
> };
> 
> class o_dim {
>   public: o_dim(o_dbc& db);
> };
> 
> 2) generate csharp wrappers for these classes 
> 
> 3) use these classes while creating enough memory
> pressure on the garbage collector such that one of the
> objects is reclaimed, even though the other object
> still has a swigCPtr reference to the just reclaimed object.
> (we generated this reclaimation with 6 to 10 65k strings)
> 
> 4) as soon as the still-live object tries to use
> the swigCPtr to the reclaimed object, an exception occurs.
> 
> I'm wondering if swig's outputted csharp code could be 
> augmented such that an object which uses getCPtr from another 
> object could setup a HandleRef or GCHandle so that the CLR
> would be informed that the objects depend upon each other,
> preventing either from being prematurely reclaimed. 
> 
> I changed by hand the swig *.cs files and using HandleRef 
> does fix the problem. My only concern now is if I know 
> enough swig internals to make a patch...
> 
> jr

-- 
------------------------------------------------------------
Joel W. Reed                                    412-257-3881
----------   http://home.comcast.net/~joelwreed/  ----------

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