I disagree entirely on the 'reasonable' implementation part. If something was that big the memory was already allocated, and it's not unlikely to grow again. Sh

I disagree entirely on the 'reasonable' implementation part. If something was that big the memory was already allocated, and it's not unlikely to grow again. Shifting memory/resources within a lifespan of a particular instance (likely used as a queue) to another resource (and staying unchanged afterwards) is a rare occurrence in practice.