4.1.3 Restartable Actors and Persistent Memory

As explained in "2.1.2 Memory Requirements and Design Considerations", the system uses persistent memory to store the following data for each executing restartable actor:

• The actor's actor image: a copy of the actor's text and initialized data segments from which the actor will be loaded after a restart.

• The actor's executing image: a copy of the actor's text and data from which the actor is executed.

This data is stored in three persistent memory blocks: one memory block for the actor image, one memory block for the executed text and one memory block for the actor data. These blocks are allocated and freed by requests from the Hot Restart Controller to the Persistent Memory Manager. Other actors cannot access or free these persistent memory blocks, although restartable actors can place additional blocks which they allocate under the control of the Hot Restart Controller. This is described in "4.2.3 Freeing Persistent Memory".