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Re: [perl #98204] Shared objects not destoryed

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Jerry D. Hedden
September 2, 2011 08:35
Re: [perl #98204] Shared objects not destoryed
Message ID:
Jerry wrote:
> threads::shared objects stored inside other
> threads::shared structures are not properly destroyed.
>  When a threads::shared object is 'removed' from a
> threads::shared structure (e.g., a hash), the object's
> DESTROY method is not called.  The attached script shows
> the cases when this occurs.

Father Chrysostomos replied:
> Caused by this commit, but that doesn’t look like very
> useful information.  Does the branch from which the
> threads changes were merged still exist, so I can try and
> find a description of the change (it added
> Perl_shared_object_destroy)?
> commit c07fbe7b8c333dbc876f7736f826d90e30b1a68b
> Author: Jerry D. Hedden <>
> Date:   Wed Dec 19 05:17:46 2007 -0500
>    [ 32658]
>    Subject: [PATCH] threads::shared 1.15
>    From: "Jerry D. Hedden" <>

When PL_destroyhook and Perl_shared_object_destroy were
added, the problem they were overcoming was that the
destruction of each threads::shared proxy was causing the
underlying shared object's DESTROY method to be called.  The
fix provided a refcount check on the shared object so that
the DESTROY method was only called with the shared object
was no longer in use.

The above works fine when delete() and pop() are used,
because a proxy is created for the stored shared object that
is being deleted (i.e., the value returned by the delete()
call), and when the proxy is destroyed, the object's DESTROY
method is called.

However, when the stored shared object is 'removed' in some
other manner (e.g., setting the storage location to
'undef'), there is no proxy involved, and hence DESTROY does
not get called for the object.

I have no idea how to fix this problem, but I will at least
document it in the next release of threads::shared.

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