CODEWITHSUNDEEP
c++memory-leaksvalgrind
Sam Gomari
Sam Gomari

Reputation: 765

Summary of Valgrind : is there a memory leak in the output?

My program is written in C++, i ran valgrind to check for memory issues. However, i am not quite sure, what happens when you have more allocated memory than freed, yet the summary says there is no leak. Here is the output of the following command:

valgrind --leak-check=full  ./myprogram

The output (Centos 6):

==28196== 
==28196== HEAP SUMMARY:
==28196==     in use at exit: 66,748 bytes in 1 blocks
==28196==   total heap usage: 7 allocs, 6 frees, 67,964 bytes allocated
==28196== 
==28196== LEAK SUMMARY:
==28196==    definitely lost: 0 bytes in 0 blocks
==28196==    indirectly lost: 0 bytes in 0 blocks
==28196==      possibly lost: 0 bytes in 0 blocks
==28196==    still reachable: 66,748 bytes in 1 blocks
==28196==         suppressed: 0 bytes in 0 blocks
==28196== Reachable blocks (those to which a pointer was found) are not shown.
==28196== To see them, rerun with: --leak-check=full --show-leak-kinds=all
==28196== 
==28196== For counts of detected and suppressed errors, rerun with: -v
==28196== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 2 from 2)
Profiling timer expired

Can somebody elaborate on the suppression issue?

Thank you

Upvotes: 1

Views: 861

Answers (1)

dbeer
dbeer

Reputation: 7193

Still reachable means that you have pointers to the memory but you didn't free it before shutdown. In most cases, this means that there isn't a problematic memory leak because most of the time this is a data structure you filled in but didn't free before shutdown.

This question Still Reachable Leak detected by Valgrind has more explanation in the top answer.

EDIT: To elaborate on suppression, valgrind can read files to suppress certain errors, and this note that is suppressed 2 from 2 means that 2 errors from the list of suppressed errors were also found. Errors are often suppressed because they are in a third party library or are known to not cause issues. For more information about suppressing errors, please check valgrind's explanation of error suppression.

Upvotes: 2

Related Questions