Re: SmartPointer & Inheritance & Explicit Constructors

 James Kanze <>
Sat, 09 Jun 2007 21:59:25 -0000
On Jun 9, 10:16 am, Gianni Mariani <> wrote:

Most of my applications since then have not been anywhere near as
complex from a lifetime management point of view and judicious use of
reference counting smart pointers eliminated all (yes - all) issues with
resource leaks. The most recent project I worked on came to life with
no memory leaks (a few handle leaks tho) to the astonishment of many of
the old timer engrs.

I'd say that this is actually fairly typical. The key word
above being "judicious". With garbage collection, there are
many cases where you don't even have to think about it. Doing
it right without garbage collection is far from impossible, but
doing it right with garbage collection is less work.

Garbage collection is not free, it can be somewhat expensive
in compute resources.

Which explains why programs using garbage collection are
typically faster than those without.

For short lived applications, it may be better since it is
likely that the collector never runs. For long running
applications, it can introduce unwanted timing issues.

That depends on the collector used. There are collectors which
give hard real-time guarantees (which malloc and free typically
don't); I've never needed one, however, so I don't know much
more than that they exist. A good incremental collector,
however, will generally not cause any problems, and it's usually
easier to tune the application (by explicitly collecting when
the system is otherwise idle, for example) with a collector than
with manual management. Of course, this depends at least
partially on memory use patterns; programs with lots of small,
short-lived allocations generally run faster with the garbage
collector; programs with very few, very long lived allocations
run slower.

The main cost of the Boehm collector is in total memory usage,
and at least at times, in locality.

I have no used the Bohem collector, I hope it becomes a standard feature
personally but I also would not support it becoming a mandatory
requirement for all C++ code.

There's no proposal for it to be mandatory; it's well recognized
that there are times when it isn't appropriate.

James Kanze (Gabi Software) email:
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