A concurrency control scheme is proposed for object-oriented database management systems (OODBMS), called ISMGL, that not only exploits semantics regarding methods to enhance the concurrency degree, but also utilizes multigranularity locking rules to decrease locking overhead. The novel aspect of ISMGL is that it combines conventional multigranularity locking and nested transaction model with utilizing commutativity of methods. The scheme is applicable for realistic OODBMSs in the presence of complex objects with shared subobjects.