Abstract: A method for checking program correctness may include executing a program on a main hardware thread in speculative execution mode on a hardware execution context on a chip having a plurality of hardware execution contexts. In this mode, the main hardware thread's state is not committed to main memory. Correctness checks by a plurality of helper threads are executed in parallel to the main hardware thread. Each helper thread runs on a separate hardware execution context on the chip in parallel with the main hardware thread. The correctness checks determine a safe point in the program up to which the operations executed by said main hardware thread are correct. Once the main hardware thread reaches the safe point, the mode of execution of the main hardware thread is switched to non-speculative. The runtime then causes the main thread to re-enter speculative mode of execution.

Abstract: A system and method for performing backfilling on an incoming flow of incoming parallel programs provided by a population of clients to a facility, the system comprising a computer-controlled prediction functionality operative to generate a current run-time prediction for at least some of the incoming parallel programs, a backfiller performing backfilling on the incoming flow of incoming parallel programs based at least partly on at least some of the run-time predictions; and a prediction updater operative, if the current run-time of an incoming parallel program currently in process exceeds the current run-time prediction, to generate an updated run-time prediction to exceed the current run-time, to re-define the current run time to equal the updated run-time prediction, thereby to allow the backfiller to continue performing backfilling based on the updated run-time prediction.