Functional programming abstractions for weakly consistent systems

In recent years, there has been a wide-spread adoption of both multicore and cloud computing. Traditionally, concurrent programmers have relied on the underlying system providing strong memory consistency, where there is a semblance of concurrent tasks operating over a shared global address space. However, providing scalable strong consistency guarantees as the scale of the system grows is an increasingly difficult endeavor. In a multicore setting, the increasing complexity and the lack of scalability of hardware mechanisms such as cache coherence deters scalable strong consistency. In geo-distributed compute clouds, the availability concerns in the presence of partial failures prohibit strong consistency. Hence, modern multicore and cloud computing platforms eschew strong consistency in favor of weakly consistent memory, where each task\u27s memory view is incomparable with the other tasks. As a result, programmers on these platforms must tackle the full complexity of concurrent programming for an asynchronous distributed system. ^ This dissertation argues that functional programming language abstractions can simplify scalable concurrent programming for weakly consistent systems. Functional programming espouses mutation-free programming, and rare mutations when present are explicit in their types. By controlling and explicitly reasoning about shared state mutations, functional abstractions simplify concurrent programming. Building upon this intuition, this dissertation presents three major contributions, each focused on addressing a particular challenge associated with weakly consistent loosely coupled systems. First, it describes A NERIS, a concurrent functional programming language and runtime for the Intel Single-chip Cloud Computer, and shows how to provide an efficient cache coherent virtual address space on top of a non cache coherent multicore architecture. Next, it describes RxCML, a distributed extension of MULTIMLTON and shows that, with the help of speculative execution, synchronous communication can be utilized as an efficient abstraction for programming asynchronous distributed systems. Finally, it presents QUELEA, a programming system for eventually consistent distributed stores, and shows that the choice of correct consistency level for replicated data type operations and transactions can be automated with the help of high-level declarative contracts

Non-blocking Synchronous Checkpointing Based On Rollback-dependency Trackability

This article proposes an original approach that applies the Rollback-Dependency Trackability (RDT) property to implement a new non-blocking synchronous checkpointing protocol, called RDT-NBS, that takes mutable checkpoints and efficiently supports concurrent initiators. Mutable checkpoints can be saved in non-stable storage and make it possible for non-blocking synchronous checkpointing protocols to save a minimal number of checkpoints in stable storage during the construction of a consistent global checkpoint. We prove that this minimality property does not hold in presence of concurrent checkpointing initiations. Even though, RDT-NBS uses mutable checkpoints to reduce the use of stable memory assuring the existence of a consistent global checkpoint in stable storage. We also present simulation results that compare RDT-NBS to quasisynchronous RDT. © 2006 IEEE.411420Baldoni, R., Helary, J., Mostefaoui, A., Raynal, M., A Communication-Induced Checkpoint Protocol that Ensures Rollback Dependency Trackability (1997) IEEE Symp. on Fault Tolerant ComputingCao, G., Singhal, M., On Coordinated Checkpointing in Distributed Systems (1998) IEEE Trans. on Parallel and Distributed Systems, 9 (12), pp. 1213-1225. , DecCao, G., Singhal, M., On the Impossibility of Min-process Non-blocking Checkpointing and an Efficient Checkpointing Algorithm for Mobile Computing Systems (1998) Proc. 27th Internat. Conf. on Parallel Processing, pp. 37-44. , New York, IEEE PressCao, G., Singhal, M., Checkpointing with Mutable Checkpoints (2003) Theoretical Computer Science, 290 (2), pp. 1127-1148. , janChandy, M., Lamport, L., Distributed Snapshots: Determining Global States of Distributed Systems (1985) ACM Transaction on Computing Systems, 3 (1), pp. 63-75. , FebE. N. Elnozahy and D. B. J. ad W. Zwaenepoel. The Performance of Consistent Checkpointing. In Proc. of the 11th Symposium on Reliable Distributed Systems, pages 86-95, Oct. 1992Garcia, I.C., Buzato, L.E., Progressive Construction of Consistent Global Checkpoints (1999) 19th IEEE International Conference on Distributed Computing Systems, , Austin, Texas, USA, JuneI. C. Garcia and L. E. Buzato. Using Common Knowledge to Improve Fixed-Dependency-After-Send. In II Workshop de Testes e Tolerância a Falhas, Curitiba, Paraná, July 2000. Available as technical report number IC-99-22 (http://www.dcc.unicamp.br/ic-tr-ftp/1999/99-22.ps.gz)Garcia, I.C., Buzato, L.E., An Efficient Checkpointing Protocol for the Minimal Characterization of Operational Rollback-Dependency Trackability (2004) 23rd Symposium on Reliable Distributed Computing Systems, , Florianópolis, Santa Catarina, OctKoo, R., Toueg, S., Checkpointing and RollbackRecovery for Distributed Systems (1987) IEEE Transaction on Software Engineering, 13, pp. 23-31. , JanKumar, P., Kumar, L., Chauhan, R., Gupta, V., A Non-intrusive Minimum Process Synchronous Checkpointing Protocol for Mobile Distributed Systems (2005) IEEE International Personal Wireless Communications, pp. 491-495. , janLamport, L., Time, Clocks, and the Ordering of Events in a Distributed System (1978) Commun. ACM, 21 (7), pp. 558-565. , JulyManivannan, D., Netzer, R.H.B., Singhal, M., Finding Consistent Global Checkpoints in a Distributed Computation (1997) IEEE Trans. on Parallel and Distributed Systems, pp. 623-627. , JuneMattern, F., Virtual Time and Global States of Distributed Systems (1989) Parallel and Distributed Algorithms, pp. 215-226. , Elsevier Science Publishers B.V, North-HollandNetzer, R.H.B., Xu, J., Necessary and Sufficient Conditions for Consistent Global Snapshots (1995) IEEE Transaction on Parallel and Distributed Systems, 6 (2), pp. 165-169Prakash, R., Singhal, M., Low-Cost Checkpointing and Failure Recovery in Mobile Computing Systems (1996) IEEE Transaction on Parallel and Distributed Systems, 7 (10), pp. 1035-1048. , OctSchmidt, F.P.R., Garcia, I.C., Buzato, L.E., Optimal Asynchronous Garbage Collection for RDT Checkpointing Protocols (2005) 25th IEEE International Conference on Distributed Computing Systems, , Columbus, Ohio, USA, JuneRandell, B., System Structure for Software Fault Tolerance (1975) IEEE Transaction on Software Engineering, 1 (2), pp. 220-232. , JuneSilva, L.M., Silva, J.G., Global Checkpointing for Distributed Programs (1992) Proc. of the 11th Symposium on Reliable Distributed Systems, pp. 155-162. , OctTsai, J., Kuo, S.-Y., Wang, Y.-M., Theoretical Analysis for Communication- Induced Checkpointing Protocols with Rollback-Dependency Trackability (1998) IEEE Transaction on Parallel and Distributed Systems, 9 (10), pp. 963-971. , OctVieira, G.M.D., Buzato, L.E., Distributed Checkpointing: Analysis and Benchmarks. Curitiba, Paraná (2006) Proceedings of Simpósio Brasileiro de Redes de Computadores, , May, To appear inWang, Y.M., Consistent Global Checkpoints that Contain a Given Set of Local Checkpoints (1997) IEEE Trans. on Computers, 46 (4), pp. 456-468. , Ap