Rust for C++ programmers – part 4: unique pointers

Re:Rust for C++ programmers – part 4: unique pointers by twic on Tuesday April 29, 2014 @01:22PM (#7668506)

I think the real problem is the move from manual memory management to garbage collection. Garbage collection has immense advantages, and is indisputably the right choice for most application programming, but it only goes fast if you feed it lots of memory.

See figure 3 of this wonderful but terrifying paper:

http://people.cs.umass.edu/~emery/pubs/gcvsmalloc.pdf

(Caveat: that was published in 2005, and garbage collection has improved since then. However, i doubt it has improved enough to invalidate its conclusions.)

The best collector there needed ~3x as much memory as a (admittedly superhumanly perfect) manually memory management to get to a competitive speed.

There are plenty of problems where that memory is available. But there are plenty where it is not. I can justify giving loads of memory to the application that makes my company money. I can't justify giving it to some tiny little log shipper or message forwarder or other random system utility that i want to run on every machine in my infrastructure.

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Re:Rust for C++ programmers – part 4: unique pointers by pjmlp on Tuesday April 29, 2014 @02:15PM (#7668920)

What does it have to do with VMs, though?

There are lots of languages with native code generation compilers that have GC[1] support.

Since the Xerox PARC days there have been system programming languages with automatic memory management (Cedar, Interlisp, Modula-3, Oberon, ....).

They were just ignored by the mainstream OS vendors, that were busy creating UNIX System V and VMS clones.

[1] RC is usually GC chapter 1 in CS books.

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Re:Rust for C++ programmers – part 4: unique pointers by twic on Tuesday April 29, 2014 @04:52PM (#7669896)

What does it have to do with VMs, though?

It doesn't. I think the point about VMs and JITs is a red herring.

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