Improved Partitioned File Creation Synchronization

When creating new file partitions, a separate temporary thread is spawned to enforce an independent transaction. It was possible in some cases that the synchronization of the new file creation thread and the subsequent file open was not properly coordinated. In the worst case, a memory free operation could take place twice causing an abnormal server termination that was noted in extensive QA testing. The synchronization of these events is now properly managed avoiding any potential errors or exceptions.