Always ensure that the QDB has a threadpool with more threads than will be required by the MME synchronization threads 
plus any other processes that may lock the MME database. The characteristics of the QDB threadpool can be set with the -
o thread options; for more information, see the QDB Developer's Guide chapter Starting QDB.

Testing of the MME has revealed that increasing the MME's maximum number of synchronization threads (<MaxThreads> in the
 MME configuration file) without also increasing the maximum number of threads available to the QDB can result in the 
QDB and MME locking up.

If multiple MME synchronization threads that need to lock the database exhaust the number of available threads, the QDB 
can find itself without the thread it requires to unlock the database, thus causing a deadlock with the MME waiting for 
the QDB to unlock the database while the QDB is waiting for the MME to release the thread it needs in order to unlock 
the database.

Deadlocks like the one described above have been observed in scenarios where the MME has attempted to synchronize 
multiple and large mediastores at the same time; for example, a USB stick with eight partitions.