Re: Info message

On 12/15/2021 12:34 AM, Domenico Panella wrote:
> Hi ,
>
> I'm getting this message when I run :
>
> valgrind --leak-check=full ./MyProg
>
> ==4189== HEAP SUMMARY:
> ==4189==     in use at exit: 192 bytes in 12 blocks
> ==4189==   total heap usage: 21 allocs, 9 frees, 3,513 bytes allocated
> ==4189==
> ==4189== LEAK SUMMARY:
> ==4189==    definitely lost: 0 bytes in 0 blocks
> ==4189==    indirectly lost: 0 bytes in 0 blocks
> ==4189==      possibly lost: 0 bytes in 0 blocks
> ==4189==    still reachable: 192 bytes in 12 blocks
> ==4189==         suppressed: 0 bytes in 0 blocks
> ==4189== Reachable blocks (those to which a pointer was found) are not shown.
> ==4189== To see them, rerun with: --leak-check=full --show-leak-kinds=all
> ==4189==
> ==4189== For lists of detected and suppressed errors, rerun with: -s
> ==4189== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)
>
> I don't see errors but some still reachable blocks.
> Now, If i run :
>
> valgrind --leak-check=full --show-leak-kinds=all -s ./MyProg
>
> ==7209== HEAP SUMMARY:
> ==7209==     in use at exit: 192 bytes in 12 blocks
> ==7209==   total heap usage: 21 allocs, 9 frees, 3,513 bytes allocated
> ==7209==
> ==7209== 48 bytes in 6 blocks are still reachable in loss record 1 of 2
> ==7209==    at 0x48437B5: malloc (in /usr/libexec/valgrind/vgpreload_memcheck-
> amd64-linux.so)
> ==7209==    by 0x4D9FC20: ??? (in /usr/lib64/libgcrypt.so.20.3.4)
> ==7209==    by 0x4D2235C: ??? (in /usr/lib64/libgcrypt.so.20.3.4)
> ==7209==    by 0x4D197E7: ??? (in /usr/lib64/libgcrypt.so.20.3.4)
> ==7209==    by 0x4012A6D: call_init (in /usr/lib64/ld-linux-x86-64.so.2)
> ==7209==    by 0x4012B6B: _dl_init (in /usr/lib64/ld-linux-x86-64.so.2)
> ==7209==    by 0x40030C9: ??? (in /usr/lib64/ld-linux-x86-64.so.2)
> ==7209==
> ==7209== 144 bytes in 6 blocks are still reachable in loss record 2 of 2
> ==7209==    at 0x48437B5: malloc (in /usr/libexec/valgrind/vgpreload_memcheck-
> amd64-linux.so)
> ==7209==    by 0x4D9FC20: ??? (in /usr/lib64/libgcrypt.so.20.3.4)
> ==7209==    by 0x4D2235C: ??? (in /usr/lib64/libgcrypt.so.20.3.4)
> ==7209==    by 0x4D197DA: ??? (in /usr/lib64/libgcrypt.so.20.3.4)
> ==7209==    by 0x4012A6D: call_init (in /usr/lib64/ld-linux-x86-64.so.2)
> ==7209==    by 0x4012B6B: _dl_init (in /usr/lib64/ld-linux-x86-64.so.2)
> ==7209==    by 0x40030C9: ??? (in /usr/lib64/ld-linux-x86-64.so.2)
> ==7209==
> ==7209== LEAK SUMMARY:
> ==7209==    definitely lost: 0 bytes in 0 blocks
> ==7209==    indirectly lost: 0 bytes in 0 blocks
> ==7209==    possibly lost: 0 bytes in 0 blocks
> ==7209==    still reachable: 192 bytes in 12 blocks
> ==7209==    suppressed: 0 bytes in 0 blocks
> ==7209==
> ==7209== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)
>
> Could you help me to understand if I'm wronging something ?
A system library (in this case libgcrypt.so) is allocating memory but 
not releasing it (keeping the memory for the life of the program).  
There are pointers to those memory blocks, so strictly speaking they are 
not lost memory.  Even this is not the fault of your code, so don't 
worry about it.  Your code does not have a memory leak.

-- 
     David Chapman      [email protected]
     Chapman Consulting -- San Jose, CA
     EDA Software Developer, Expert Witness
     www.chapman-consulting-sj.com
     2018-2019 Chair, IEEE Consultants' Network of Silicon Valley



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