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

std::pmr — custom allocators for containers.

1#include <memory_resource>
2
3std::pmr::monotonic_buffer_resource pool;
4std::pmr::vector<int> v(&pool);
5
6// Fast allocation from pool
7for (int i = 0; i < 1000; i++) {
8    v.push_back(i); // allocates from pool
9}
10// All memory freed at once when pool is destroyed

Resources:

• monotonic_buffer_resource: fast, no deallocation
• pool_resource: reusable memory pool
• new_delete_resource: default (heap)

Benefits:

• Faster allocation for many small objects
• Batch deallocation
• Cache-friendly allocation patterns
• Useful for game engines, parsers