How do I use polymorphic_allocator with containers in high-performance C++?

In high-performance C++, memory management plays a critical role, especially when using standard containers. The polymorphic_allocator is a powerful tool that allows for customizable memory allocation strategies, enhancing performance by reducing fragmentation and improving cache locality.

To utilize polymorphic_allocator with standard containers such as std::vector or std::map, follow these general steps:

  1. Define a custom allocator that derives from std::pmr::polymorphic_allocator.
  2. Create a memory resource to back your allocator.
  3. Use your custom allocator in the container's template argument.

Here is an example demonstrating how to use polymorphic_allocator with a std::vector:

#include <iostream> #include <vector> #include <memory_resource> int main() { // Create a memory pool. std::pmr::monotonic_buffer_resource pool; // Create a polymorphic allocator using the pool. std::pmr::polymorphic_allocator alloc(&pool); // Create a vector using the custom allocator. std::pmr::vector<int> vec(alloc); // Adding elements to the vector. vec.push_back(1); vec.push_back(2); vec.push_back(3); // Display elements. for (const auto& element : vec) { std::cout << element << " "; } return 0; }

C++ polymorphic_allocator memory management high-performance C++ standard containers custom allocator cache locality

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