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Re: Memory leaks - what causes them?
by Gregg Liming
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Gregg Liming wrote:
> David Norwood wrote:
>
>> To tell you the truth, I've seen this question asked many times but
>> never seen an example of code that causes a memory leak in misterhouse.
>
> It's always been unbounded arrays that I've seen be the culprit.
> Specifically, shoving the same value or object into an array w/o
> checking on its existence first (if appropriate). An example here of
> proper bounding is Base_Item::add_item_if_not_present. If memory leaks
> happen on reload, then it's usually non-object arrays that I've seen in
> both common code and libs.
>
> Also, consuming memory doesn't necessarily mean a "leak" (where the
> occurrence is accidental) since some code/objects "accumulate"
> data/objects over time.
>
> I don't see my own mh instance grow by more than 10M over a week. So, I
> attribute that to either "slow leaks" or just normal object "accumulated
> bloat". And, since I routinely develop libs, then I have to restart
> usually far more frequently. Any time I've seen memory leaks grow by
> more than that, tracking it down requires you to know a great deal about
> what your specific environment/config is implying as well as detailed
> knowledge of the code. Unfortunately, no "magic bullets" for easy
> detection (unless good "gut intuition" counts).
I forgot one thing... folks that don't understand using # noloop or the
# noloop=start and # noloop=end "blocks" on methods/statements that do
not inherently perform bounding are just asking for trouble. If you
have much personal user code, then that's the first place I'd look.
Since I don't always want to have to scrutinize the code, I tend to
"over-use" # noloop even when I know it's pointless (e.g., on "add"
methods).
Gregg
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> David Norwood wrote:
>
>> To tell you the truth, I've seen this question asked many times but
>> never seen an example of code that causes a memory leak in misterhouse.
>
> It's always been unbounded arrays that I've seen be the culprit.
> Specifically, shoving the same value or object into an array w/o
> checking on its existence first (if appropriate). An example here of
> proper bounding is Base_Item::add_item_if_not_present. If memory leaks
> happen on reload, then it's usually non-object arrays that I've seen in
> both common code and libs.
>
> Also, consuming memory doesn't necessarily mean a "leak" (where the
> occurrence is accidental) since some code/objects "accumulate"
> data/objects over time.
>
> I don't see my own mh instance grow by more than 10M over a week. So, I
> attribute that to either "slow leaks" or just normal object "accumulated
> bloat". And, since I routinely develop libs, then I have to restart
> usually far more frequently. Any time I've seen memory leaks grow by
> more than that, tracking it down requires you to know a great deal about
> what your specific environment/config is implying as well as detailed
> knowledge of the code. Unfortunately, no "magic bullets" for easy
> detection (unless good "gut intuition" counts).
I forgot one thing... folks that don't understand using # noloop or the
# noloop=start and # noloop=end "blocks" on methods/statements that do
not inherently perform bounding are just asking for trouble. If you
have much personal user code, then that's the first place I'd look.
Since I don't always want to have to scrutinize the code, I tend to
"over-use" # noloop even when I know it's pointless (e.g., on "add"
methods).
Gregg
------------------------------------------------------------------------------
Create and Deploy Rich Internet Apps outside the browser with Adobe(R)AIR(TM)
software. With Adobe AIR, Ajax developers can use existing skills and code to
build responsive, highly engaging applications that combine the power of local
resources and data with the reach of the web. Download the Adobe AIR SDK and
Ajax docs to start building applications today-http://p.sf.net/sfu/adobe-com
________________________________________________________
To unsubscribe from this list, go to: http://sourceforge.net/mail/?group_id=1365
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