Communicators

Communicators

• Communicators are used to create independent ``message universes''.
• Communicators are used to disambiguate message selection when an application calls a library routine that performs message passing. Nondeterminacy may arise
  • if processes enter the library routine asynchronously,
  • if processes enter the library routine synchronously, but there are outstanding communication operations.
• A communicator
  • binds together groups and contexts
  • defines the scope of a communication operation
  • is represented by an opaque object
  • is referenced by a handle