Re: [Boost-users] [interprocess] Memory deallocation doesn't seem to work

Subject: Re: [Boost-users] [interprocess] Memory deallocation doesn't seem to work
From: Ion Gaztañaga (igaztanaga_at_[hidden])
Date: 2009-09-23 12:40:15

Stephan Menzel escribió:
> Just an update
> 
> On Wed, Sep 23, 2009 at 3:43 PM, Stephan Menzel
> <stephan.menzel_at_[hidden]> wrote:
>> ptr = m_segment->allocate_aligned(static_cast<size_t>(rawsize), 128);
>>
>> Now after a while the segment will have no more room for further
>> blocks. So I delete some of them to gain more room:
>>
>> m_segment->deallocate(raw.get());
> ...
> 
>> This makes me believe that either deallocate didn't do a good job...
> 
> Actually it just turned out this is the case. I tried among many other
> things replacing the allocate_aligned() with an ordinary allocate()
> and this works. So I'm afraid this looks a lot like a bug in
> interprocess to me. Pointers returned by allocate_aligned are aligned
> but cannot be deallocated. At least not in a way that would have the
> mem actually available afterwards.

Can you give me a use case to reproduce the problem? This seems to work 
in may windows machine:

#include <vector>
#include <boost/interprocess/managed_windows_shared_memory.hpp>

int main()
{
    using namespace boost::interprocess;
    typedef boost::interprocess::
       managed_windows_shared_memory  shared_segment;

    std::vector<void *> ptrs;
    shared_segment m_segment(create_only, "shmem", 4096*16);
    try{
       while(1){
          //Now I have several allocate_aligned operations:
          ptrs.push_back(m_segment.allocate_aligned(128, 128));
       }
    }
    catch(...){
       m_segment.deallocate(ptrs.back());
       ptrs.pop_back();
       ptrs.push_back(m_segment.allocate_aligned(128, 128));
    }
    return 0;
}

Ion