Moved the locking around the right function :-/. (Race reproduced in about 25% of cases so far).

castor/exception/Backtrace.cpp

@@ -30,10 +30,11 @@
 
 castor::exception::Backtrace::Backtrace(): m_trace() {
   void * array[200];
+  g_lock.lock();  
   size_t depth = ::backtrace(array, sizeof(array)/sizeof(void*));
   g_lock.lock();
   char ** strings = ::backtrace_symbols(array, depth);
-  g_lock.unlock();
+
   if (!strings)
     m_trace = "";
   else {