Re: [Boost-users] custom allocators, pool_alloc release_memory() seems to be broken

Subject: Re: [Boost-users] custom allocators, pool_alloc release_memory() seems to be broken
From: B Hart (bhartsb_at_[hidden])
Date: 2010-03-18 16:48:20

nope, continued upwards and release_memory() always returns false.
Also, I would say that release_memory is broken, or needing revision,
if one has to guess what the pool size is.

On Thu, Mar 18, 2010 at 7:14 AM, Steven Watanabe <watanabesj_at_[hidden]> wrote:
> AMDG
>
> B Hart wrote:
>>
>> I tried contacting Stephen the pool_allocator author, but his e-mail
>> is invalid (shouldn't the docs be updated?)
>>
>> Here is what I wrote in case someone else here can offer some help:
>>
>> I'm trying unsuccessfully to use your Boost::pool_alloc.  In the
>> documentation at the boost website:
>> http://www.boost.org/doc/libs/1_42_0/libs/pool/doc/interfaces.html
>> it says:
>>
>> // Exiting the function does NOT free the system memory allocated by
>> the pool allocator
>>  // You must call
>>  //  boost::singleton_pool<boost::pool_allocator_tag,
>> sizeof(int)>::release_memory()
>>  // in order to force that
>>
>> release_memory() does not seem to work.  Not sure why.  I called a
>> function in my code to verify my processes memory usage, and see that
>> indeed memory was not being released.  I also google searched and
>> found that others experienced the same:
>>
>
> The problem is not release_memory per se.  The problem
> is the interaction between singleton_pool, pool_allocator
> and std::set.  The example is using vector, which (probably)
> allocates exactly the type that you give it.  std::set is allocating
> a different type.  pool_allocator uses multiple singleton_pools,
> one for each size of object.  release_memory would work if
> you could find the size of the object that std::set is actually allocating.
> Without knowing that, the best you can do is something like
>
> // assume that the sizes are multiples of 4 bytes.
> boost::singleton_pool<boost::pool_allocator_tag, 4>::release_memory();
> boost::singleton_pool<boost::pool_allocator_tag, 8>::release_memory();
> boost::singleton_pool<boost::pool_allocator_tag, 12>::release_memory();
> boost::singleton_pool<boost::pool_allocator_tag, 16>::release_memory();
> boost::singleton_pool<boost::pool_allocator_tag, 20>::release_memory();
> boost::singleton_pool<boost::pool_allocator_tag, 24>::release_memory();
> boost::singleton_pool<boost::pool_allocator_tag, 28>::release_memory();
> boost::singleton_pool<boost::pool_allocator_tag, 32>::release_memory();
> // hope that's enough...
>
> In Christ,
> Steven Watanabe
>
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