One of the main reasons it is difficult to write multithreaded code is that current shared-memory multicore systems can execute code nondeterministically. Each time a multithreaded application runs, it can produce a different output even if supplied with the same input. This frustrates debugging efforts and limits the ability to properly test multithreaded code, becoming a major obstacle to widespread adoption of parallel programming.

Past efforts to address the problem of nondeterminism have primarily focused on deterministic replay and deterministic parallel programming models. The former is useful only for debugging, while the latter is typically domain-specific. In contrast, this project envisions that shared memory multiprocessor systems should always behave deterministically when executing any shared-memory parallel program. The core idea is to make inter-thread communication appear to be fully deterministic by guaranteeing equivalence to a deterministic serialized execution. This can be made efficient by employing speculation and exploiting properties of memory sharing behavior of applications.

This project includes: (1) developing an architecture for efficient deterministic multiprocessing, from mechanisms to the hardware/software interface, (2) addressing system issues, e.g., executing an operating system in deterministic multiprocessors, and (3) leveraging the deterministic multiprocessing hardware/software interface to create tools for debugging, testing and bug avoidance.

Current contacts: Luis Ceze, Dan Grossman, and Tom Bergan.

Publications

Input-Covering Schedules for Multithreaded Programs (WoDet 2013), Tom Bergan, Luis Ceze, and Dan Grossman.

DDOS: Taming Nondeterminism in Distributed Systems (ASPLOS 2013), Nick Hunt, Tom Bergan, Luis Ceze, and Steve Gribble.

The Case For Merging Execution- and Language-level Determinism with MELD (WoDet 2012), Joseph Devietti, Dan Grossman, and Luis Ceze.

The Deterministic Execution Hammer: How Well Does it Actually Pound Nails? (WoDet 2011), Tom Bergan, Joseph Devietti, Nicholas Hunt, and Luis Ceze.

RCDC: A Relaxed-Consistency Deterministic Computer (ASPLOS 2011), Joseph Devietti, Jacob Nelson, Tom Bergan, Luis Ceze, and Dan Grossman.

Deterministic Process Groups in dOS (OSDI 2010), Tom Bergan, Nick Hunt, Luis Ceze, and Steve Gribble.

CoreDet: A Compiler and Runtime System for Deterministic Multithreaded Execution (ASPLOS 2010), Tom Bergan, Owen Anderson, Joseph Devietti, Luis Ceze, and Dan Grossman.

DMP:Deterministic Shared Memory Multiprocessing (ASPLOS 2009), Joseph Devietti, Brandon Lucia, Luis Ceze, and Mark Oskin. (Selected for IEEE Micro Top Picks. An earlier version appeared in SHCMP'08 held with ISCA'08).

dOS+DDOS Source Code

The source code for dOS (OSDI 2010) and DDOS (ASPLOS 2013) is available here. The source is not currently maintained.

RCDC Simulator Source Code and Data

The source code for the RCDC simulator is available here. A README describing how to use the code, and its overall design, is here.

We have also posted interactive versions of the graphs from the paper.

CoreDet Source Code

Our lawyers want you follow this link to download the CoreDet source code: link. Source code is available for the original CoreDet paper (ASPLOS 2010), as well as the updated version of CoreDet used in the RCDC paper (ASPLOS 2011).