Re: Garbage Collection - The Trash Begins To Pile Up

"Le Chaud Lapin" <>
8 Jan 2007 15:27:38 -0500
{ beware, links can get broken into multiple lines. -mod }

James Kanze wrote:

Mirek Fidler wrote:

James Kanze wrote:

Again: bad programmers will write bad code, and good programmers
will write good code. The only significant difference is the
amount of effort it will take them to do it; garbage collection
offers good programmers an additional tool, to use WHEN

Do you honestly believe that, in a commercial environment, programmers
who choose to use GC will be able to use it as they wish without regard
for what those who choose not to use it, and vice-versa?

GC doesn't absolutely prevent memory leaks; I don't know where
you got that idea from. [snippage]

58 Google hits on exact match of following string:
"garbage collection prevents memory leaks"

The first link is interesting. Erik Poupaert writes:
"I may also have fallen victim to the myth that automatic garbage
collection prevents memory leaks"

It gets even more interesting if the double-quotes are removed from the
search string. 760,000 hits. And the links that show are up are very

Java In A Nutshell writes:
"At first glance, it might seem that garbage collection prevents all
memory leaks because it reclaims all unused objects."

Microsoft writes:
"In Microsoft Visual Studio 2005 or in Microsoft Visual Studio .NET, a
comprehensive garbage collection package and managed memory can stop
memory leaks, but, under some circumstances, a program may appear to be
leaking memory.

Interesting. A technology that works but appears to be not, like a

"Because of the garbage collection package that is implemented in the
Microsoft .NET Framework, it is not possible to have a memory leak in
managed code. This suggests two questions: How then can a memory leak
occur? Why does it appear that you have a memory leak? "

There it is again. It works, yes it does not.

M.Shoaib Khan. writes about his C++ garbage collector at The Code
" This simple garbage collector de-allocates memory when an object is
no longer referenced, hence preventing memory leaks.

Comparing C++ and Java writes:
"Automatic garbage collection prevents memory leaks."

But that's beside the point. Garbage collection isn't, IMHO,
about preventing memory leaks per se; your code shouldn't leak
memory, even without garbage collection. It's about reducing
the programmer effort necessary to prevent them, or more
generally, the programmer effort necessary to impose a
deterministic lifetime on objects which don't need it (but do
need a lifetime which cannot be modeled on scope).

Tim Murray writes:
I am developing a console application in Managed C++
with Visual Studio .Net. I am trying to learn how to
correctly destroy variables. When I run my program, with
every added action, the memory usage increases but the
only memory being allocated in each function is for
temporary local variables, and should not persist.
Calling the garbage collector does not seem to do anything
to clean up the memory usage. I am currently setting each
variable back to NULL upon leaving the functions, but it
does not seem to be working. Are variables in Managed C++
not cleaned up when they go out of scope? Am I supposed
to take extra precautions to get them to be released? Is
there any way for me to find out what is leaking?"

Jeffrey Richter writes:
"Garbage collection in the Microsoft .NET common language runtime
environment completely absolves the developer from tracking memory
usage and knowing when to free memory."

Dan Kalev writes:
"We can conclude that a GC-enabled programming language necessitates a
different design of classes. Therefore, if C++ were to incorporate a
built-in GC, its Standard Library would have to be rewritten from
scratch; worse yet, C++ programmer would have to learn different
resource management idioms. Forget about smart pointers such as
auto_ptr, or RAII in general."

"Is this the worst thing that can happen? Not quite. Many believe that
the solution to the wholesale redesign problem is by making GC
optional. I suspect that doing so would complicate matters even

I did a Google search for "garbage" collection and "difficult", and
there were so many hits, decided to stop here.

-Le Chaud Lapin-

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