Re: How to give selective access to the methods in a class?
Chris Smith wrote:
toton <abirbasak@gmail.com> wrote:
setting an object null, when it is no more in use anyway helps gc?
I'll just respond to this. No, except in specific circumstances or
unless you've done something else wrong, setting a reference to null
doesn't help garbage collection.
I'm surprised, and curious about this statement. On the face of it, Java
garbage collection is prevented by an object being reachable, and
assigning null to a reference may transition an object from reachable to
unreachable.
For example, one of my Java programs was a simulation of a computer
processor-memory interconnect. The main objects were representations of
transactions and of hardware components, such as processors and memory
modules, and queues connecting components. There are relatively few
components and queues, but they exist for the whole duration of the
simulation. There are many transactions, but each should exist for only
a relatively short time.
At times, a simulated component can go idle for an extended period. In
an attempt to aid garbage collection, I made sure that as soon as a
component had finished its work on a transaction, it set its current
transaction reference to null.
Similarly, the queue implementation did some null reference assignments
to ensure that each queue only had references to transactions that were
actually on the queue, not to transactions that had been on it.
The invariant I was aiming for was that a long lived object should have
a reference to a Transaction if, and only if, it still had work to do on
the Transaction.
Was I wasting my time? It seemed to reduce memory use.
Patricia