Abstract: A method is provided to virtualize a mutually exclusive lock of a shared immutable object. A determination is made whether any threads have locked the immutable shared object. If threads have not locked the immutable shared object, threads of different tasks are allowed to fast lock and unlock the immutable shared object. If a thread requests the lock of an immutable shared object and the object is fast locked by another thread when both threads are from an equivalent task, the lock of the immutable shared object is inflated and the requesting thread is blocked. If a thread requests the lock of an immutable shared object and the object is fast locked by another thread when both threads are from different tasks, the lock of the immutable shared object is virtualized and granted to the requesting thread.

Abstract: A method is provided enabling concurrent garbage collection of a young generation of a task with other tasks executing in a multi-tasking virtual machine. A first record is provided for each thread which has a value in an old generation memory after each thread successfully allocates an object in the old generation memory. A second record is provided for each thread which has a memory address value. Threads of a garbage-collecting task are stopped and an end of scan value for the task is calculated. Garbage collection on threads associated the garbage-collected task are permitted when one of two conditions involving either second records or second records and first records are met.

Abstract: Techniques have been developed whereby concurrency control mechanisms such as nested databases can be expressed in terms of operations implemented by various flexible transaction processing systems. For example, one such implementation of nested databases is particularly suitable for transaction processing systems that provides a lock delegation facility and which allow specification of ignore-conflict relationships between locking capabilities. By providing techniques that support movement of objects from a database to a subdatabase thereof, as well as termination (e.g., commit or abort) of transactions and databases (including subdatabases), transaction processing systems can provide advanced transaction models with unconventional concurrency control mechanisms. Some realizations allow specification of uses of parameters with lock modes and facilitate transformation of such uses into a form suitable for utilization in execution environments that support ignore-conflict relationships.