A desktop 3D printer in safety-critical Java

Strøm, Tórur Biskopstø; Schoeberl, Martin

doi:10.1145/2388936.2388949

Cited by 10 publications

(6 citation statements)

References 17 publications

(15 reference statements)

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“…In our previous locking paper, we included the SCJ RepRap use case and argued that the CAM locking unit allowed us to expand the system to 4 cores and improve performance. However, the predicted performance numbers presented in our locking paper were not correct, as we ignored the delay owing to memory arbitration for a CMP system.…”

Section: Discussionmentioning

confidence: 99%

Hardware locks for a real‐time Java chip multiprocessor

Strøm

Puffitsch

Schoeberl

2016

Concurrency and Computation

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A software locking mechanism commonly protects shared resources for multithreaded applications. This mechanism can, especially in chip-multiprocessor systems, result in a large synchronization overhead. For real-time systems in particular, this overhead increases the worst-case execution time and may void a task set's schedulability. This paper presents 2 hardware locking mechanisms to reduce the worst-case time required to acquire and release synchronization locks. These solutions are implemented for the chipmultiprocessor version of the Java Optimized Processor. The 2 hardware locking mechanisms are compared with a software locking solution as well as the original locking system of the processor. The hardware cost and performance are evaluated for all presented locking mechanisms. The performance of the betterperforming hardware locks is comparable with that of the original single global lock when contending for the same lock. When several noncontending locks are used, the hardware locks enable true concurrency for critical sections. Benchmarks show that using the hardware locks yields performance ranging from no worse than the original locks to more than twice their best performance. This improvement can allow a larger number of real-time tasks to be reliably scheduled on a multiprocessor real-time platform.

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Section: Discussionmentioning

confidence: 99%

Hardware locks for a real‐time Java chip multiprocessor

Strøm

Puffitsch

Schoeberl

2016

Concurrency and Computation

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“…Below a description of the test cases can be found. scjreprap The scjreprap test case is an implementation of the controller software for a reprap 3D printer on top of the JOP/SCJ implementation as part of a master's project [13]. It was unknown whether this test case contained illegal assignments.…”

Section: Methodsmentioning

confidence: 99%

Private memory allocation analysis for safety-critical Java

Dalsgaard

Hansen

Schoeberl³

2012

Proceedings of the 10th International Workshop on Java Technologies for Real-Time and Embedded Systems

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Safety-critical Java (SCJ) avoids garbage collection and uses a scope based memory model. This memory model is based on a restricted version of RTSJ [3] style scopes. The scopes form a clear hierarchy with different lifetimes. Therefore, references between objects in different scopes are only allowed from objects allocated in scopes with a shorter lifetime to objects allocated in scopes with a longer lifetime.To ensure memory safety, programmers are required to either manually annotate the application with complex annotations, rely on a runtime test of each reference assignment, or statically analyze all reference assignments and avoid runtime checks when all assignments are proven to be correct. A violation of the assignment rule at runtime leads to an unchecked exception. For safety-critical code that needs to be certified, runtime exceptions must be avoided and the absence of illegal reference assignments needs to be proven. In this paper we present a static program analysis tool that automates the proof that no illegal assignments occur.

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“…A lack of SCJ use-cases motivated the development of a RepRap 3D printer in SCJ [48]. A RepRap printer melts plastic and extrudes it in 3 dimensional space according to printing instructions (G-codes).…”

Section: Reprapmentioning

confidence: 99%

Certifiable Java for Embedded Systems

Schoeberl

Dalsgaard

Hansen

et al. 2014

Proceedings of the 12th International Workshop on Java Technologies for Real-Time and Embedded Systems

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The Certifiable Java for Embedded Systems (CJ4ES) project aimed to develop a prototype development environment and platform for safety-critical software for embedded applications. There are three core constituents: A profile of the Java programming language that is tailored for safety-critical applications, a predictable Java processor built with FPGA technology, and an Eclipse based application development environment that binds the profile and the platform together and provides analyses that help to provide evidence that can be used as part of a safety case. This paper summarizes key contributions within these areas during the three-year project period. In the conclusion the overall result of the project is assessed.

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A desktop 3D printer in safety-critical Java

Cited by 10 publications

References 17 publications

Hardware locks for a real‐time Java chip multiprocessor

Hardware locks for a real‐time Java chip multiprocessor

Private memory allocation analysis for safety-critical Java

Certifiable Java for Embedded Systems

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