Asynchronous Point-To-Point Communication

Abstract

Point-to-point synchronous communication provides a uniform model to deal with both local and inter-process synchronization and communication. However, this model sometimes turns out to produce over-synchronization and useless context switching. Let us use the global completion checking algorithm (GC, see Chapter 6 for details) to illustrate this point. The algorithm consists of a probe process that checks global completion by sending message waves from root to leaves and back on a process virtual binary-tree. Each node in the tree (a process) runs the local component of the overall probe process as a concurrent thread whose behavior can be sketched out as follows:

• — wait for a message from father,

• — update and forward the message to each son,

• — wait for reply from each son,

• — integrate replies, and

• — send result to father.