maat/docs/concurrency.md

Maat concurrency

Safe Points

• Creation of shared upvalues
• Marking a collectable object shared

Synchronization Points

(if more than one thread to execute Maat code)

• Check environment type(single or multi-threaded?)
• Shared short strings
• Cached strings
• Int -> Str cache
• Propagating over shared collectable objects.
• Insertion of shared objects into LSOs
• Shared memory operations (READ, WRITE, READ-MODIFY-WRITE(RMW))

Memory shared accross maatines are via global symbols and upvalues, Maat attemps to automatically synchronize concurrent access to shared memory either through mutexes or atomic operations.

Suppose we are in a multi-threaded environment and that variable x is accessible to all maatines, having more than one threads to execution maat code implies more then one maatine, let us determine all the synchronization points in each of the operations below.

1. Write operation

   x = 20
   

2. Read operation

   say x + 100
   

3. RMW (Read-Modify-Write) operation

   x = x + 1
   

   x = [1, 2]
   
   x.push(3)
   

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