What is std::pmr (polymorphic memory resource)?

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**std::pmr** — custom memory allocators for STL containers. ```cpp #include // Monotonic buffer (fast, no individual deallocation) char buffer[1024]; std::pmr::monotonic_buffer_resource pool{ buffer, sizeof(buffer) }; std::pmr::vector vec(&pool); vec.push_back(1); vec.push_back(2); // Pool allocator (reuse freed memory) std::pmr::pool_options opts; opts.max_blocks_per_chunk = 100; std::pmr::unsynchronized_pool_resource pool2(opts); std::pmr::vector vec2(&pool2); // Performance benefit // Game engines, databases, network servers // where many small allocations are needed ``` **Resource types:** - monotonic_buffer_resource — arena-style, fast. - synchronized_pool_resource — thread-safe pool. - unsynchronized_pool_resource — single-thread pool. - null_memory_resource — no allocation.

C++: What is std::pmr (polymorphic memory resource)?