How the GC distinguishes code from data
schveiguy at yahoo.com
Wed Jan 5 14:03:38 PST 2011
On Wed, 05 Jan 2011 16:56:47 -0500, Simen kjaeraas
<simen.kjaras at gmail.com> wrote:
> %u <wfunction at hotmail.com> wrote:
>> If I have a large uint, it's practically guaranteed to have data that
>> looks like pointers, and that might cause memory leaks.
> If you have allocated a large uint, most likely ìt will be flagged
> NO_SCAN, meaning it has no pointers in it, and the GC will ignore it.
There is another problem that I recently ran into. If you allocate a
large memory block, even one marked as not containing pointers, there is a
medium probability that a 'fake' pointer exists that points *at* that
block, not from it. This means that uint may never get collected unless
you manually free it.
>> Furthermore, if the GC moves
>> things around, it would corrupt my data. How is this handled?
> The current GC does not move things. One could write such a GC for D (I
> believe), and in such a case data would be marked NO_MOVE if for whatever
> reason it cannot be moved.
A moving GC cannot exist without precise scanning. Anything that is
marked from a conservative block (one that has no pointer map) would not
be able to move.
More information about the Digitalmars-d-learn