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Re: Memory leaks - what causes them?
by Gregg Liming
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David Norwood wrote:
> Gregg 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.
>
> I've narrowed my memory leak problem down to the rss_file_process subroutine
> in my mh/code/common/rss_subscriber.pl script. Each of the arrays and
> hashes are defined locally to the subroutine in "my ..." statements.
> Doesn't that mean the memory they take up is freed when the subroutine
> returns?
I can't think of a reason why they wouldn't be.
> Would you mind taking a look at the rss_file_process subroutine in
> mh/code/common/rss_subscriber.pl and see if you find a problem?
Nothing immediately "jumps out". But a couple of questions:
1) Do you ever see "Process Eval results: ... " displayed? If so, then
I wonder if there is a problem if the untie is never reached (line 210
in rss_subscribed.pl).
2) Have you tried uncommenting exit and commenting out exec 'true' in
Process_Item (lines 193 and 196)? You'd have to assess whether doing so
might cause issues elsewhere. Given the comments there about DESTROY, I
wonder if there's missing garbage collection.
3) Is there any purpose to $list and @itemslist in rss_file_process?
(this is more a "housekeeping" question than anything else).
I'll stare at it some more; but, am quite curious about #1 and #2.
Gregg
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> Gregg 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.
>
> I've narrowed my memory leak problem down to the rss_file_process subroutine
> in my mh/code/common/rss_subscriber.pl script. Each of the arrays and
> hashes are defined locally to the subroutine in "my ..." statements.
> Doesn't that mean the memory they take up is freed when the subroutine
> returns?
I can't think of a reason why they wouldn't be.
> Would you mind taking a look at the rss_file_process subroutine in
> mh/code/common/rss_subscriber.pl and see if you find a problem?
Nothing immediately "jumps out". But a couple of questions:
1) Do you ever see "Process Eval results: ... " displayed? If so, then
I wonder if there is a problem if the untie is never reached (line 210
in rss_subscribed.pl).
2) Have you tried uncommenting exit and commenting out exec 'true' in
Process_Item (lines 193 and 196)? You'd have to assess whether doing so
might cause issues elsewhere. Given the comments there about DESTROY, I
wonder if there's missing garbage collection.
3) Is there any purpose to $list and @itemslist in rss_file_process?
(this is more a "housekeeping" question than anything else).
I'll stare at it some more; but, am quite curious about #1 and #2.
Gregg
------------------------------------------------------------------------------
Open Source Business Conference (OSBC), March 24-25, 2009, San Francisco, CA
-OSBC tackles the biggest issue in open source: Open Sourcing the Enterprise
-Strategies to boost innovation and cut costs with open source participation
-Receive a $600 discount off the registration fee with the source code: SFAD
http://p.sf.net/sfu/XcvMzF8H
________________________________________________________
To unsubscribe from this list, go to: http://sourceforge.net/mail/?group_id=1365
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