BARRIER-BASED ACCESS TO A SHARED RESOURCE IN A MASSIVELY PARALLEL COMPUTER SYSTEM

An apparatus, program product and method utilize a barrier-based mechanism for arbitrating access to a shared resource in a massively parallel computer system. In a first processor among a plurality of processors in a massively parallel computer system, the number of times a barrier has been entered by processors in the massively parallel computer system in association with attempting to access the shared resource may be monitored, and the shared resource may be accessed by the first processor once the number of times the barrier has been entered matches a priority value associated with the first processor. As such, on massively parallel computer systems where potentially thousands of processors may attempt to concurrently access the same shared resource, the access by such processors may be coordinated in a logical fashion to reduce the risk of overwhelming the shared resource due to an excessive number of concurrent access attempts to the shared resource.