Re: valgrind errors

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От Shachar Shemesh
Тема Re: valgrind errors
Дата
Msg-id 4087F1DC.6050009@shemesh.biz
обсуждение исходный текст
Ответ на Re: valgrind errors  (Shachar Shemesh <psql@shemesh.biz>)
Ответы Re: valgrind errors  ("Min Xu (Hsu)" <xu@cs.wisc.edu>)
Список pgsql-hackers
Shachar Shemesh wrote:

> Tom Lane wrote:
>
>> I suspect valgrind is complaining because XLogInsert is memcpy'ing a
>> struct that has allocation padding in it.  Which of course is a bogus
>> complaint ...
>>  
>>
> As far as I remember (couldn't find modern documentation on the 
> matter) Valgrind is resitant to this problem. When a block of memory 
> is copied, the initialized/uninitialized status is copied along. It 
> only complains when an actual operation is performed using 
> uninitialized memory. This was developed for the explicit reason of 
> avoiding the problem you describe.
>
>          Shachar
>
Found it:
http://developer.kde.org/~sewardj/docs-2.0.0/mc_main.html, section 3.3.2

> It is important to understand that your program can copy around junk 
> (uninitialised) data to its heart's content. Memcheck observes this 
> and keeps track of the data, but does not complain. A complaint is 
> issued only when your program attempts to make use of uninitialised data.


What IS possible, however, is that there is a bug in one of the 
underlying libraries.

-- 
Shachar Shemesh
Lingnu Open Source Consulting
http://www.lingnu.com/



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