The \emph{group mutual exclusion (GME)} problem is a generalization of the classical mutual exclusion problem in which every critical section is associated with a \emph{type} or \emph{session}. Critical sections belonging to the same session can execute concurrently, whereas critical sections belonging to different sessions must be executed serially. The well-known read-write mutual exclusion problem is a special case of the group mutual exclusion problem.

In this work, we present a suite of GME algorithms for an asynchronous shared-memory system under the cache coherent (CC) model. Our GME algorithms have the feature that they do not require an \emph{a priori} knowledge of the set of processes in the system and all their important complexity measures depend only on the number of different sessions that can be requested by processes. This makes them especially suitable for a dynamic system in which the set of processes may change over time. To our knowledge, no existing GME algorithm satisfies this property. Our GME algorithms provide different trade offs between complexity and fairness.