Well, you might want to read up on how OSs handle memory under the hood, and that virtual memory != physical, and that task manager and stuff like that can't show the real memory usage.

Nonetheless, tracing GCs do have some memory overhead in exchange for better throughput. This is basically the same concept as using a buffer.

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And can you tell which of these websites use Java from "the feel"? AWS cloud infra, a significant chunk of Google, Apple's backends, Alibaba, Netflix?