Deletion Prevention

Regions require careful programming to avoid deadlocks.

A thread controlling a region should not suspend itself or it might hold the region indefinitely
When threads need to control more than one region, waiting for all processes must always be done in the same order and released in the reverse order or else a dead lock may occur.

A thread that controls a region only is deleted once it gives up control of the region. A region that is controlled by a thread only is deleted once the thread gives up control of this region. This may result in unexpectedly long delays in executing the delete operations – even in deadlocks if the application is implemented in an awkward way.