Re: [Boost-users] [Wave] effect of allocation of data structures oncopying data structures
Andreas Sæbjørnsen wrote:
I need some advice regarding how I should copy the boost data structures I get from 'advanced_preprocessing_hooks.h'. The task at hand is to copy some of the data structures from Wave and store it separate form the memory Wave allocates so that after the Wave preprocessing step has finished all it's memory can be freed.
Example: e.g making a copy of the 'std::vector<std::list<PreprocessingInfo::token_type,boost::fa st_pool_allocator<PreprocessingInfo::token_type> > >' representing the arguments in the expansion of a macro in the function 'expanding_function_like_macro'.
Syntactically it would be gre at to be able to make a copy using the operator=, but as far as I can see this is only possible if I am also using the fast_pool_allocator. If I use the fast_pool_allocator I am afraid that my copies will be put into the memory pool allocated by Wave and therefore that memory cannot be safely freed. Is this corect?
I'm not sure here. My (unverified) guess is, that the memory pool will be free'd only after the last item allocated from it got free'd. This shouldn't be a problem as long as the memory pool doesn't live in a shared library which gets unloaded prematurely.
After looking at the code and the docs again I discovered the following: the boost::fast_pool_allocator is build on top of a thread local singleton pool. This pool gets allocated before entering main and gets free'd after main exits. Same should be true for shared libraries. So yes, you're running into problems only: 1) if you have your Wave application compiled into a shared library and 2) if you use data from the allocator used by Wave in a different module after the first shared library was explicitely unloaded from memory. HTH Regards Hartmut
But anyway, doesn't using std::copy() for the embedded list<>'s allow to change to any adequate data structure?
Regards Hartmut
My scenario is number 1) here, so I have to be very careful with the memory use. I should then probably use the std::copy using the inserter to copy the values into a data structure allocated using the standard allocator. When trying to free the memory allocated by Wave when I use it as a shared library, is it enough to delete the variable declaration of type context_type? Regards Andreas On 5/10/06, Hartmut Kaiser < hartmut.kaiser@gmail.com> wrote:
Andreas Sæbjørnsen wrote:
I need some advice regarding how I should copy the boost data structures I get from 'advanced_preprocessing_hooks.h'. The task at hand is to copy some of the data structures from Wave and store it separate form the memory Wave allocates so that after the Wave preprocessing step has finished all it's memory can be freed.
Example: e.g making a copy of the 'std::vector<std::list<PreprocessingInfo::token_type,boost::fa st_pool_allocator<PreprocessingInfo::token_type> > >' representing the arguments in the expansion of a macro in the function 'expanding_function_like_macro'.
Syntactically it would be gre at to be able to make a copy using the operator=, but as far as I can see this is only possible if I am also using the fast_pool_allocator. If I use the fast_pool_allocator I am afraid that my copies will be put into the memory pool allocated by Wave and therefore that memory cannot be safely freed. Is this corect?
I'm not sure here. My (unverified) guess is, that the memory pool will be free'd only after the last item allocated from it got free'd. This shouldn't be a problem as long as the memory pool doesn't live in a shared library which gets unloaded prematurely.
After looking at the code and the docs again I discovered the following: the boost::fast_pool_allocator is build on top of a thread local singleton pool. This pool gets allocated before entering main and gets free'd after main exits. Same should be true for shared libraries.
So yes, you're running into problems only: 1) if you have your Wave application compiled into a shared library and 2) if you use data from the allocator used by Wave in a different module after the first shared library was explicitely unloaded from memory.
HTH Regards Hartmut
But anyway, doesn't using std::copy() for the embedded list<>'s allow to change to any adequate data structure?
Regards Hartmut
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Andreas Sæbjørnsen wrote:
My scenario is number 1) here, so I have to be very careful with the memory use. I should then probably use the std::copy using the inserter to copy the values into a data structure allocated using the standard allocator.
I don't think so. The problems _may_ happen, when you're going to explicitly unload the Wave shared library before your actual application exits (or while you're still using the memory allocated there - bad programming style anyways). This is very unlikely to occur.
When trying to free the memory allocated by Wave when I use it as a shared library, is it enough to delete the variable declaration of type context_type?
Could you elaborate, please? I have not been able to understand your question. Regards Hartmut
When trying to free the memory allocated by Wave when I use it as a shared library, is it enough to delete the variable declaration of type context_type?
Could you elaborate, please? I have not been able to understand your question.
I am going to use some tools to profile the memory usage so that I can better understand what is happening and/or if I need to be worried about any memory deallocation issues. After that I will probably be able to ask more specific questions if there are some issues. Thanks for all your help! Regards Andreas
participants (2)
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Andreas Sæbjørnsen -
Hartmut Kaiser