title: Valgrind possibly lost memory
body: <p>When running valgrind with <code>--leak-check=full</code> the generated reports include information about memory "possibly lost".</p>
  
  <p>There is some information on this in the valgrind manual, as well as some example reports.</p>
  
  <p><a href="http://valgrind.org/docs/manual/mc-manual.html" rel="nofollow noreferrer">http://valgrind.org/docs/manual/mc-manual.html</a></p>
  
  <pre><code>LEAK SUMMARY:
     definitely lost: 4 bytes in 1 blocks
     indirectly lost: 0 bytes in 0 blocks
       possibly lost: 0 bytes in 0 blocks
     still reachable: 95 bytes in 6 blocks
                        of which reachable via heuristic:
                          stdstring          : 56 bytes in 2 blocks
                          length64           : 16 bytes in 1 blocks
                          newarray           : 7 bytes in 1 blocks
                          multipleinheritance: 8 bytes in 1 blocks
          suppressed: 0 bytes in 0 blocks
  </code></pre>
  
  <p>In my own system, i get plenty of "possibly" lost memory when executing my multi-threaded test binary with valgrind.</p>
  
  <p>What exactly does it mean that valgrind reports memory as "possibly lost"? Was it lost or wasn't it in this particular execution. Memory leakage should be more black and white than "possibly lost" in my opinion.</p>