Re: Argument scope
Peter Duniho wrote:
All parameters in Java are passed by value. See my other reply.
BGB wrote:
except references, which are the value of the reference.
Actually, that's *including* references, whose value is a pointer.
This is a question I got wrong the first time I took a practice Java test.
All parameter passing in Java is pass-by-value. Period. Passing a reference
by value is not the same thing as passing by reference.
well, then presumably the value-type is inlined within the class or
similar, rather than being placed on the stack. this is no big issue.
Currently, in the present, likely on your very computer, the (commercial) JVM
(at least in "-server" mode) will inline some things, enregister others, and
convert references into stack-based primitive values. It's already doing the
implementation strategies that have been mentioned here.
...
in my VM at least, garbage objects can easily end up sitting around for
many minutes or more with the GC never realizing that they have become
garbage (my GC basically just uses concurrent mark/sweep, and garbage
will usually sit around until whenever is the next GC pass).
Currently, in the present, likely on your very computer, the (commercial) JVM
supports a number of GC strategies that address the issues you raise, all
important issues in the GC world.
There are a number of white papers related to the subject available on the
Oracle, erst Sun, site.
The generational strategy deployed by default doesn't require the GC to
"realize that [objects] have become garbage". True, collected objects may
never be finalized or released, but that's only if they needn't be.
Otherwise, GC only cares about live objects for the most part, and for the
most part in an idiomatic Java program those constitute somewhere around one
in twenty.
Java's GC is triggered by a need for memory rather than an observation of end
of life for some objects. Also, Java offers a smorgasbord of GC
implementations to leverage, say, multi-core platforms.
--
Lew