[CppAD] possible memory leak

[Jochen Siehr]

Thanks!

Am 30.07.2011 16:02, schrieb Brad Bell:
> CppAD has been modified so that if multiple threads are not used, the
> user does not need to deal with the more complex memory management
> aspects of omp_alloc. To be specific, if the function
> CppAD::omp_alloc::set_max_num_threads
> is not called, the memory management (from the users point of view) has
> not changed. I think that this satisfied the request below.
>
> See the documentation for return_memory
> http://www.coin-or.org/CppAD/Doc/return_memory.htm
> and the whats new headings 07-28 and 07-29 on
> http://www.coin-or.org/CppAD/Doc/whats_new_11.htm#07-28
>
> Note that the function max_num_threads has been replaced by
> set_max_num_threads and the function get_max_num_threads has been added
> to the user API.
>
>
> On 7/15/2011 9:36 AM, schattenpflanze at arcor.de wrote:
>> Brad,
>>
>>> [snip]
>>> So there seems to be a memory leak. It would be nice, if this could be
>>> fixed.
>> I had a look into this. The "memory leak" is due to the fact that
>> free_available(0) is never called. Thus, the omp_alloc memory manager
>> never really frees the memory, but rather stores it for possible future
>> use. Moreover, even if free_available(0) is called before the end of
>> main(), the created ADFun object is still in scope. Thus, its memory
>> cannot yet be freed.
>> If I define the ADFun object within a block scope and call
>> free_available(0) after that block closes (see attachment), no memory
>> leak is detected by valgrind.
>>
>> We should definitely find a way to free all memory automatically at the
>> end of a program. I suggest calling free_available() for every thread
>> (up to the number set in max_num_threads) in the destructor of some
>> auxiliary class A, and including an object of that type as a static
>> class member of AD<Base>  (or any other class).
>>
>> In addition, we could also think about deleting returned memory by
>> default, and only activating the current behaviour (storing returned
>> memory as "available") on user request. Something like
>> omp_alloc::keep_memory_available(bool setting).
>>
>>
>> Best regards,
>> Peter
>>
>>
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>
>
>
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-- 
Jochen Siehr
http://www.siehr.net