Valgrind does not throw errors, but not all heap allocations have been freed

Question

This is what I get after running my program with Valgrind:

1    jscherman@jscherman:~/ClionProjects/algo2-t4-tries$ g++ Set.hpp tests.cpp DiccString.hpp && valgrind --leak-check=yes --show-leak-kinds=all ./a.out                      
2    ==6823== Memcheck, a memory error detector
3    ==6823== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
4    ==6823== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info
5    ==6823== Command: ./a.out
6    ==6823== 
7    test_empty_dicc...ok
8    test_copy_constructor...ok
9    test_define_defined...ok
10    test_get..ok
11    test_remove...ok
12    test_remove_tiny...ok
13    test_keys...ok
14    ==6823== 
15    ==6823== HEAP SUMMARY:
16    ==6823==     in use at exit: 72,704 bytes in 1 blocks
17    ==6823==   total heap usage: 282 allocs, 281 frees, 275,300 bytes allocated
18    ==6823== 
19    ==6823== 72,704 bytes in 1 blocks are still reachable in loss record 1 of 1
20    ==6823==    at 0x4C2DC10: malloc (vg_replace_malloc.c:299)
21    ==6823==    by 0x4EC3EFF: ??? (in /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.21)
22    ==6823==    by 0x40104E9: call_init.part.0 (dl-init.c:72)
23    ==6823==    by 0x40105FA: call_init (dl-init.c:30)
24    ==6823==    by 0x40105FA: _dl_init (dl-init.c:120)
25    ==6823==    by 0x4000CF9: ??? (in /lib/x86_64-linux-gnu/ld-2.23.so)
26    ==6823== 
27    ==6823== LEAK SUMMARY:
28    ==6823==    definitely lost: 0 bytes in 0 blocks
29    ==6823==    indirectly lost: 0 bytes in 0 blocks
30    ==6823==      possibly lost: 0 bytes in 0 blocks
31    ==6823==    still reachable: 72,704 bytes in 1 blocks
32    ==6823==         suppressed: 0 bytes in 0 blocks
33    ==6823== 
34    ==6823== For counts of detected and suppressed errors, rerun with: -v
35    ==6823== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

There seems to be no leaks, as the last line of output says. However, we have this line too:

17    ==6823==   total heap usage: 282 allocs, 281 frees, 275,300 bytes allocated

How do I have no errors, but still have a selection that has not been freed? Is something wrong with my program, or maybe Valgrind did something behind the scenes?

Answer 1

The backlink provided by valgrind shows that the corresponding memory allocation was made in the initialization function of one of the shared libraries loaded by the application, apparently by the C ++ library itself.

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