We propose a scheme within which parallel programs with potential synchronization bottlenecks run efficiently. In the straightforward implementations which use basic locking schemes, the execution time for the program parts with bottlenecks increases significantly when the number of processors increases. Our scheme makes the parallel performance for the bottleneck parts of programs close to the sequential performance while maintaining the e ciency with which the nonbottleneck parts run. Experiments with a 64-processor SMP and a 128-processor DSM machine confirmed that parallel programs implemented with our scheme perform much better than parallel programs implemented with other widely-used locking schemes.

. One typically defines a read-only method as a method that does not perform any write operations; however, with respect to a multi-threaded program, we augment this interpretation and let a read-only method be one that does not write to a memory location visible to more than one thread. Such a method can execute concurrently with other read-only methods. With the relaxation of mutual exclusion in mind, we present a read-write analysis that employs the ideas of shape analysis and escape analysis to identify readonly methods in Java. Approximately 31% of the methods in the JDK 1.2 core libraries meets this definition of read-only---nearly 50% more than those that do not perform any write operations. 1

This thesis is a description of a compiler and runtime technique for the efficient management of threads including their mutual exclusion. The target area for this work is parallel languages for shared-memory multiprocessors. The goal of this work is to achieve a situation in which the execution time either decreases or remains unchanged as the number of processors is increased. We call this performance model the satisfactory performance model. Existing parallel programming systems do not always perform according to this satisfactory model. This is the case when there are modules in the program such that concurrent invocations of the modules are serialized. We call these modules bottleneck modules. When bottleneck modules are present they prevent operation according to the satisfactory performance model since the overhead incurred because of bottleneck modules increases with the number of processors. This overhead includes communications with memory for the sharing of memory objects am...

This paper describes a mechanism for "fusing" concurrent invocations of exclusive methods. The target of our work is object-oriented languages with concurrent extensions. In the languages, concurrent invocations of exclusive methods are serialized; only one invocation executes immediately and the others wait for their turn. The mechanism fuses multiple waiting invocations to a cheaper operation such as a single invocation.