02-26-2015
Quote:
C does have a "virtual machine".
It has a real machine.
Quote:
The C virtual machine has a call stack and a heap formed at opposite ends of the same memory block. The stack may have a fixed size, but the heap is everything else.
It's not really a block of memory. It's all translated from virtual addresses to real addresses. Both the stack and the heap are automatically "sized" through the magic of virtual memory. The kernel itself, behind the scenes, cares very little about which is which -- it just assigns memory in fixed-sized blocks from the pile. See
The Paging Game for a general explanation on how paging works.
Quote:
If you need memory you use it and hand it back when done.
Agreed. There's no java VM to worry about, only the kernel itself. You use it, and the kernel either lets you or not.
It doesn't get "handed back", though. Your program keeps it for later, just in case you need to allocate again -- this makes it faster, and probably why he wanted to preallocate, but the kernel handles this for you.
Quote:
There's no portable way to put an upper limit on the heap.
Check out
setrlimit.
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