Concurrent Constraint-Based Memory Machines: A Framework for Java Memory Models

A central problem in extending the von Neumann architecture to petaflop computers with millions of hardware threads and with a shared memory is defining the memory model [Lam79,AG95,APP99]. Such a model must specify the behavior of concurrent (conditional) reads and writes to the same memory locations. We present a simple, general framethe specification of memory models based on an abstract machine that uses sets of (interdependent) order and value constraints to communicate between threads and main memory. The separation of order constraints allows a parametric treatment of different order consistency models such as sequential consistency, location consistency, happens-before consistency (HB-consistency), etc. The use of value constraints allows a simple formulation of the semantics of concurrent dependent reads and writes in the presence of look-ahead and speculative computation. Memory is permitted to specify exactly those linkings (mappings from read events to write events) wh...

• Type: Conference
• Year: 2004
• Where: ASIAN
• Authors: Vijay A. Saraswat
• Keywords: ASIAN 2004, Memory Model, Order Consistency Models, Value Constraints