Re: [Boost-bugs] [Boost C++ Libraries] #11638: stored weak_ptr of track object will prevent the track object memory being freed

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #11638: stored weak_ptr of track object will prevent the track object memory being freed
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2015-09-10 17:24:51

#11638: stored weak_ptr of track object will prevent the track object memory being
freed
-------------------------------------+-------------------------------------
  Reporter:  Lutts Cao               |      Owner:  fmhess
  <lutts.cao@…>                      |     Status:  closed
      Type:  Bugs                    |  Component:  signals2
 Milestone:  To Be Determined        |   Severity:  Problem
   Version:  Boost 1.56.0            |   Keywords:  signals2 weak_ptr
Resolution:  invalid                 |  memory leak
-------------------------------------+-------------------------------------
Changes (by fmhess):

 * status:  new => closed
 * resolution:   => invalid

Comment:

 You may be happier with signals2 from boost 1.59.  It deletes slot objects
 inside the signal (and their tracked weak_ptrs) ASAP after slot
 disconnection, rather than putting it off for the signal to garbage
 collect at some later point.

 While weak_ptr causing a delay in the deallocation of memory for
 shared_ptr created with allocate_shared is interesting, it is an issue
 with allocate_shared, not signals2.  My guess is allocate_shared allocates
 a single block of memory to contain both the pointed-at object and the
 shared reference count, in order to minimize the number of memory
 allocations.  Thus the memory cannot be freed until both the pointed-at
 object and the shared reference count are destroyed.  Since the weak_ptr
 has a handle to the shared reference count, it delays the deallocation.

 I'm closing this ticket, if there is still a need for an added cleanup API
 when using signals2 from 1.59, please open a separate ticket for that
 feature request.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/11638#comment:2>
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