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den_jekk
Beginner
75 Views

Does tbb:concurrent_queue grow like std::vector? How to release its buffers?

Hello, I'm wondering if tbb:concurrent_queue can grow its internal buffers when it's under high load, and then not release the buffers?

How to obtain any information about the buffers and/or release them?

In the vector, you have methods like .reserve() to allocate and .swap(vector()) to completely release any buffers.


Regards,
Denis

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Anton_M_Intel
Employee
75 Views

pop() deallocates free pages as well as clear() and assign(). Do you have any experimental evidence that tbb::concurrent_queue keeps free buffers allocated? Can it be tbb_allocator/scalable_allocator instead which doesn't return the memory to the system immediately?

A small addition regarding vector, it also has shrink_to_fit() in C++0x and TBB, formerly known as compact() in tbb::concurrent_vector.
den_jekk
Beginner
75 Views

Is the scalable_allocator used by default? I will now investigate the case, but maybe you have already the information. Is it possible to get total amount of memory occupied by a scalable allocator?
Anton_M_Intel
Employee
75 Views

Yes, because default allocator for concurrent_queue<> is cache_aligned_allocator<> which uses scalable_allocator by default if tbbmalloc.dll is in the paths. BTW, it can be [mostly] changed by template argument:
concurrent_queue >

No, I guess there is no way to query such an information from scalable allocator. But actually you can reuse this memory anyway by using it for next allocations ;-)
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