title: *** glibc detected *** double free or corruption (fasttop):
body: <p>A call to clear on a QByteArray generates the following exception:</p>
  
  <p><strong>* glibc detected *</strong> /home/yan/FPS2/FPS2: double free or corruption (fasttop): </p>
  
  <p>0 ?? 
  1 ?? <br>
  2 free <br>
  3 QByteArray::clear() <br>
  4 FPSengine::getDatagrams <br> 
  5 FPSengine::xmitData <br>
  6 FPSengine::getData <br>
  7 threadDatalog::run <br>
  8 ?? <br>
  9 start_thread <br>
  10 clone <br>
  11 ?? 0</p>
  
  <p>is this a qt bug or could it have something to do with my code? I know QObjects arent thread safe (QT definition not multiple threads calling the same function of the same object instance)but my function has mutexes.  Also I very rarely get this error even though the same function is called frequently. P.S.  A way to prevent this is to env var MALLOC_CHECK_ 0</p>
  
  <p>this url relates a similar problem and some posts seems to imply its caused by an incompatible version of glibc. </p>
  
  <p><a href="https://stackoverflow.com/questions/882422/glibc-detected-perl-double-free-or-corruption-prev-0x0c2b7138">*** glibc detected *** perl: double free or corruption (!prev): 0x0c2b7138 ***</a></p>