Allocate a block of size s. First tries to allocate from the existing
list of already-created allocators. If neither can satisfy the request,
creates a new allocator by calling make(s) and delegates the request
to it. However, if the allocation fresh off a newly created allocator
fails, subsequent calls to allocate will not cause more calls to make.
Allocate a block of size s. First tries to allocate from the existing list of already-created allocators. If neither can satisfy the request, creates a new allocator by calling make(s) and delegates the request to it. However, if the allocation fresh off a newly created allocator fails, subsequent calls to allocate will not cause more calls to make.