Abstract: An I/O control window is created on a user's terminal screen when a parallel program is executing. The I/O control window displays an array of graphical elements (preferably small colored squares), which are partitioned into groups of one or more such elements, each partition representing a task (or thread) of the parallel program. In each partition there is one graphical element which represents the I/O status of the task or thread represented by that partition and is called an I/O status indicator. Each I/O status indicator is capable of assuming any one of several different graphical states (each graphical state preferably being a color for the graphical element), one of which indicates that the corresponding task or thread has provided text output that has not been displayed to the user yet and another of which indicates that the corresponding task (or thread) is requesting text input from the user.

Abstract: A protocol for achieving atomic multicast in a parallel or distributed computing environment. The protocol guarantees concurrency atomicity with a maximum of m-1 message passes among the m server nodes of the system. Under one embodiment of the protocol, an access component message is transferred to the server nodes storing data to be accessed. The first server node of the plurality generates a token to be passed among the accessed nodes. A node can not process its request until it receives the token. A node may pass the token immediately upon ensuring that it is the current expected token.