Importance

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Abstract

In a computing environment containing a plurality of state machines that communicate by passing messages on connections, a construct called a clique controls access into a set of the state machines by worker threads that deliver the messages arriving on the connections. A clique is a collection of connections into the set of the state machines that have a common relationship for which concurrency isolation is required. Each clique has a message queue and a guard for marking the clique as busy or not busy, The guard prevents more than one thread at a time from delivering messages that arrive on connections in the clique to the set of state machines, thus ensuring concurrency isolation of the set of state machines. Messages that arrive on a connection in the clique while the clique is marked as busy are queued in the clique's message queue. The queued messages are delivered one at a time by a same worker thread that is currently busy in the clique. This operation can save a thread switch when a state machine generates an outgoing message that results in an immediate incoming message to the state machine, such as a buffer full message, and thus makes efficient use of the worker threads.

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First Claim