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Multi-Version eXecution (MVX) is a technique that deploys many equivalent versions of the same program — variants — as a single program, with direct applications in important fields such as: security, reliability, analysis, and availability. MVX can be seen as “online Record/Replay (RR)”, as RR captures a program’s execution as a log stored on disk that can later be replayed to observe the same execution. Unfortunately, current MVX techniques target programs written in C/C++ and do not support programs written in managed languages, which are the vast majority of code written nowadays. This paper presents the design, implementation, and evaluation of Jmvx— a novel system for performing MVX and RR on programs written in managed languages. Jmvx supports programs written in Java by intercepting automatically identified non-deterministic methods, via a novel dynamic analysis technique, and ensuring that all variants execute the same methods and obtain the same data. Jmvx supports multi-threaded programs, by capturing synchronization operations in one variant, and ensuring all other variants follow the same ordering. We validated that Jmvx supports MVX and RR by applying it to a suite of benchmarks representative of programs written in Java. Internally, Jmvx uses a circular buffer located in shared memory between JVMs to enable fast communication between all variants, averaging 5% |47% performance overhead when performing MVX with multithreading support disabled|enabled, 8% |25% when recording, and 13% |73% when replaying.
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Processor-Oblivious Record and Replay
Record-and-replay systems are useful tools for debugging non-deterministic parallel programs by first recording an execution and then replaying that execution to produce the same access pattern. Existing record-and-replay systems generally target thread-based execution models, and record the behaviors and interleavings of individual threads. Dynamic multithreaded languages and libraries, such as the Cilk family, OpenMP, TBB, etc., do not have a notion of threads. Instead, these languages provide a processor-oblivious model of programming, where programs expose task-parallelism using high-level constructs such as spawn/sync without regard to the number of threads/cores available to run the program. Thread-based record-and-replay would violate the processor-oblivious nature of these programs, as they incorporate the number of threads into the recorded information, constraining the replayed execution to the same number of threads. In this paper, we present a processor-oblivious record-and-replay scheme for such languages where record and replay can use different number of processors and both are scheduled using work stealing. We provide theoretical guarantees for our record and replay scheme --- namely that record is optimal for programs with one lock and replay is near-optimal for all cases. In addition, we implemented this scheme in the Cilk Plus runtime system and our evaluation indicates that processor-obliviousness does not cause substantial overheads.
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- Award ID(s):
- 1527692
- PAR ID:
- 10026255
- Date Published:
- Journal Name:
- Proceedings of the 22Nd ACM SIGPLAN Symposium on Principles and Practice of Parallel Programming
- Page Range / eLocation ID:
- 145 to 161
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1145/3018743.3018764
