Fixed ==25829== Thread #1: pthread_cond_{signal,broadcast}: dubious: associated lock is not held by any thread

==25829== at 0x4C2A1D5: pthread_cond_broadcast_WRK (hg_intercepts.c:891)
==25829== by 0x654A758: std::condition_variable::notify_all() (in /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.17)
==25829== by 0x132305A: ProducerConsumerQueue<SQLOperation*>::Cancel() (ProducerConsumerQueue.h:100)
==25829== by 0x13229A7: DatabaseWorkerPool<WorldDatabaseConnection>::~DatabaseWorkerPool() (DatabaseWorkerPool.h:70)
==25829== by 0x6C6CB21: __run_exit_handlers (exit.c:78)
==25829== by 0x6C6CB74: exit (exit.c:100)
==25829== by 0x6C54EF3: (below main) (libc-start.c:276)

src/server/shared/Threading/ProducerConsumerQueue.h

@@ -82,7 +82,7 @@ public:
 
     void Cancel()
     {
-        _queueLock.lock();
+        std::unique_lock<std::mutex> lock(_queueLock);
 
         while (!_queue.empty())
         {
@@ -95,8 +95,6 @@ public:
 
         _shutdown = true;
 
-        _queueLock.unlock();
-
         _condition.notify_all();
     }