Memory allocation can be avoided by using preallocated buffers for storage. Yeah, that limits the number of maximum elements and could waste memory like hell, b

Memory allocation can be avoided by using preallocated buffers for storage. Yeah, that limits the number of maximum elements and could waste memory like hell, but have to live with that and get performance in return. Race could be eliminated by using separate dirty and free lists (circular buffers, probably implemented as arrays, with the same number of elements as the data storage has). Like declare your storage as a global array, add all of its indexes to the freelist. When adding data to the storage, pop an index from the front of the freelist, fill the given slot of the array, push the index to the back of the dirty list. When processing data, pop an index from the front of the dirty list, process the slot, push the index to the back of the freelist.