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第32届中国控制与决策会议

作者： Jian Wang Shihui Duan Jun Xu Song Wang Qiang Ling University of Science and Technology of China China Academy of Information and Communications Technology of MIIT Key Laboratory of Internet and industrial integration and innovation of MIIT

In some scenarios,we need to combine multiple video streams and pictures into a single *** this paper,we develop an application to synthesize two channel video stream and two channel *** application can be used for synthetic display of multiple network video streams and offline video synthetic *** the single thread decoding of multiple video streams takes a lot of time,we propose the use of a multithreading producer-consumer *** makes full use of the advantages of multi-core CPU and improves the programming *** our experiments,we compare video synthesis through single thread and *** is much faster than single threading.

关键词： Multiple video streams synthesis multithreading concurrent programming

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EXECUTION REPLAY WITH COMPACT LOGS FOR SHARED-MEMORY PROGRAMS

EXECUTION REPLAY WITH COMPACT LOGS FOR SHARED-MEMORY PROGRAM...

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IFIP WG10.3 Working Conference on Applications in Parallel and Distributed Computing

作者： LEVROUW, LJ AUDENAERT, KMR VANCAMPENHOUT, JM

ISBN: (纸本)0444818707

Execution replay is an essential part of debugging. Since explicitly parallel programs can be non-repeatable, trace and replay mechanisms have been proposed to support the debugging task. We introduce a novel trace and replay mechanism for shared-memory programs, based on Lamport clocks. We compare the new scheme with Leblanc's 'Instant Replay' and Netzer's 'optimal tracing'. Our approach produces (much) smaller traces than both existing approaches. Moreover, in comparison with Netzer's approach, our approach induces much less overhead during the recording phase.

关键词： concurrent programming TESTING AND DEBUGGING

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Automated Analysis of Weak Memory Models

Automated Analysis of Weak Memory Models

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作者： Artem Yushkovskiy Aalto University

学位级别：硕士

Software verification is considered to be a hard computational problem vul- nerable to the state explosion problem. concurrent software verification raises the complexity of the problem to a power determined by all the possible in- terleavings of states of the system. Moreover, the architecture of a modern shared-memory multi-core processor and optimisations performed by a com- piler can cause program behaviour that is unexpected from the point of view of traditional concurrency. The guarantees that an execution environment can provide to a programmer are formalised in its Weak Memory Model (WMM). Over the last decade, weak memory models were defined for multiple hard- ware architectures and programming languages. This opens new challenges in software verification with respect to a weak memory model. Most existing tools that perform memory model-aware software analysis tools examine behaviours of the program against a single memory model. The first tool that analyses the portability of a concurrent program from one platform to another is Porthos [PFH + 17a] released in April 2017. Porthos can verify that the program is portable from the source platform S to the target platform T by checking that the program has no extra states under T. For that, it performs an SMT-based bounded reachability analysis by encoding the constraints of the program and two memory models M S and M T into a single SMT-formula. Although the approach has been proven to be efficient, the tool accepts as input the small C-like toy language. Current thesis aims to rework Porthos by extending its input language, so that it is able to process real-world C programs. However, current implementation of Porthos can be considered hardly extensible, which raises the need to redesign its whole architecture in order to increase the robustness, transparency, efficiency and extensibility. The result of the work is PorthosC, a framework for SMT-based memory model-aware analysis.

关键词： Weak memory models concurrent programming software verification portability analysis bounded reachability analysis SMT-encoding

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React++: A Lightweight Actor Framework in C++

React++: A Lightweight Actor Framework in C++

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作者： Khan, Md Navid Alvee University of Waterloo

学位级别：硕士

Distributed software remains susceptible to data races and poor scalability because of the widespread use of locks and other low-level synchronization primitives. Furthermore, using this programming approach is known to break encapsulation offered by object-oriented programming. Actors present an alternative model of concurrent computation by serving as building blocks with a higher level of abstraction. They encapsulate concurrent logic in their behaviors and rely only on asynchronous exchange of messages for synchronization, preventing a broad range of concurrent issues by eschewing locks. Existing actor frameworks often seem to focus on CPU-bound workloads and lack an actor-oriented I/O infrastructure. The purpose of this thesis is to investigate the scalability of user-space I/O operations carried out by actors. It presents an experimental actor framework named React++, with an M: N runtime for cooperative scheduling of actors and an integrated I/O subsystem. Load distribution is policy-driven and uses a variant of the randomized work-stealing algorithm. The evaluation of the framework is carried out in three stages. First, the efficiency of message delivery, scheduling and load balancing is assessed by a set of micro-benchmarks, where React++ retains a competitive score against several well-known actor frameworks. Next, a web server built on React++ is shown to be on par with its fastest event-driven counterparts in the TechEmpower plaintext benchmark. Finally, the runtime of an existing messaging library (ZeroMQ) is augmented with React++, replacing the backend and delegating all network I/O to actors without incurring any substantial overhead.

关键词： C++ actor model concurrent programming work-stealing non-blocking I/O event-driven programming

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Development of a distributed web server utilizing Elixir

Development of a distributed web server utilizing Elixir

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作者： Ruokolainen, Timo LAPPEENRANTA UNIVERSITY OF TECHNOLOGY

学位级别：硕士

Elixir is a relatively new functional programming language, which is based on the Erlang programming language. This master's thesis takes a look at the tools provided by Erlang and Elixir, and examines what a functional and concurrency oriented programming language can offer for the development of distributed systems. Elixir runs on Erlang's virtual machine that simplifies the development of concurrent applications. A distributed web server is developed using Elixir, which illustrates the potential benefits gained from utilizing Elixir. The web server employs many of the tools and techniques described in this thesis to induce concurrency, distribution and fault tolerance to the system. It is concluded that Elixir is a strong option for this type of project.

关键词： functional programming Erlang Elixir distributed systems concurrent programming web server

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Dec :: Pdp11 :: Rt11 :: Micropowerpascal :: Aa-M388A-Tc Introtomicropowerpascal Jan82

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2016年

Dec :: Pdp11 :: Rt11 :: Micropowerpascal :: Aa-M388A-Tc Introtomicropowerpascal Jan82 by published by

关键词： aa-m388a-tc application concurrent concurrent programming file type introtomicropowerpascal jan82 kernel memory memory image micropowerpascal object module object modules pascal pdp11 process process control processes program semaphore source code static process target target system utility programs

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The Little Book of Semaphores

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2006年

作者： Allen B.Downey

Description: After each problem, the book offers a hint before showing a solution, giving students a better chance of discovering solutions on their own. The book covers the classical problems, including “Readers-writers,” “Producer-consumer”, and “Dining Philosophers.” In addition, it collects a number of not-so-classical problems, some written by the author and some by other teachers and textbook writers. Readers are invited to create and submit new problems

关键词： concurrent programming programming

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FGSCM: uma abordagem de omissão de lock transacional com granularidade fina na resolução de conflitos

FGSCM: uma abordagem de omissão de lock transacional com gr...

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作者： Sousa, Gustavo José Universidade Estadual Paulista

Omissão de lock é uma técnica onde operações de aquisição e liberação de lock são omitidas (especulação) de forma a permitir que regiões críticas c... 详细信息

Omissão de lock é uma técnica onde operações de aquisição e liberação de lock são omitidas (especulação) de forma a permitir que regiões críticas compartilhando um mesmo lock possam executar concorrentemente, permitindo assim se explorar um nível maior de concorrência em programas que utilizam esse método popular de sincronização. Para se manter o princípio de atomicidade, as modificações no estado do programa realizadas pela região crítica são mantidas em um buffer interno e são efetivadas apenas ao fim da mesma. Em caso de inconsistências, diferentes políticas em como proceder são possíveis, o que diferencia as diversas abordagens de omissão de lock encontradas na literatura. Por exemplo, a abordagem original, Speculative Lock Elision (SLE), que é implementada no nível microarquitetural, recorre a adquirir o lock de forma tradicional quando uma especulação falha. Em algumas situações, esta política conservadora acaba por restringir o ganho em desempenho originalmente pretendido por impor um volume de sincronização desnecessário (lemming effect). Uma forma de superar tal limitação é o emprego de omissão de lock transacional (Transactional Lock Elision, em inglês), onde a especulação de regiões críticas se dá por meio de transações e o controle de execução é devolvido ao software em eventos de transações abortadas, o que permite que diferentes estratégias sejam empregadas com o objetivo de permitir execução concorrente mesmo em presença de falha de especulação. Neste contexto, uma das abordagens possíveis é o esquema chamado Software-assisted Conflict Management (SCM), onde um lock auxiliar é utilizado para sincronizar transações abortadas e, assim, manter o lock original livre, permitindo que outras transações prossigam sua execução. No presente trabalho, uma extensão ao SCM é proposta, o esquema Fine-grained Software-assisted Conflict Management (FGSCM), onde múltiplos locks são utilizados para permitir que transações abortadas por conflitos em diferentes regiões

关键词： Programação Concorrente Omissão de Lock Memória Transacional concurrent programming Lock Elision Transactional Memory Dissertação de mestrado

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Transactions in the Era of Non Volatile Memory and Heterogeneous Memory Architectures 21

Transactions in the Era of Non Volatile Memory and Heterogen...

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ACM/SPEC International Conference on Performance Engineering (ICPE)

作者： Romano, Paolo Univ Lisbon Inst Super Tecn Lisbon Portugal INESC ID Lisbon Portugal

ISBN: (纸本)9781450383318

Transactions are a simple, yet powerful, abstraction that aims at masking programmers from the complexity of having to ensure correct and efficient synchronization of concurrent *** introduced in the domain of database systems, transactions have recently garnered significant interest in the broader domain of concurrent programming, via the Transactional Memory (TM) paradigm. Nowadays, hardware supports for TM are provided in commodity CPUs (e.g., by Intel and IBM) and, at the software level, TM has been integrated in mainstream programming languages, such as C/C++ and *** this talk I will present the novel challenges and research opportunities that arise in the area of TM due to the emergence of two recent hardware trends, namely Non-Volatile Memory (NVM) and heterogeneous computing *** the front of NVM, I will focus on the problem of how to allow the execution of transactions over NVM using unmodified commodity hardware TM (HTM) implementations. However, the reliance of commodity HTM implementations on CPU caches raises a crucial problem when applications access data stored in NVM from within a HTM transaction. Since CPU caches are volatile in today's systems, HTM implementations do not guarantee that the effects of a hardware transaction are atomically transposed to PM when the transaction commits --- although such effects are immediately visible to subsequent *** this talk, I will overview somoe recent approaches to tackle this problem and present experimental results highlighting the existence of several bottlenecks that hinder the scalability of existing solutions. Next, I will show how these limitations can be addressed by presenting SPHT. SPHT introduces a novel commit logic that considerably mitigates the scalability bottlenecks of previous alternatives, providing up to 2.6x/2.2x speedups at 64 threads in, resp., STAMP/TPC-C. Moreover, SPHT introduces a novel approach to log replay that employs cross-transaction log l

关键词： concurrent programming Transactional Memory Non-Volatile Memory Heterogeneous Architectures

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Pattern-Based Verification for Multithreaded Programs

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ACM TRANSACTIONS ON programming LANGUAGES AND SYSTEMS 2014年第3期36卷 9-9页

作者： Esparza, Javier Ganty, Pierre Poch, Tomas Tech Univ Munich Fak Informat D-80290 Munich Germany IMDEA Software Inst Madrid Spain Charles Univ Prague Fac Math & Phys CR-11636 Prague 1 Czech Republic

Pattern-based verification checks the correctness of program executions that follow a given pattern, a regular expression over the alphabet of program transitions of the form w(1)* ... w(n)*. For multithreaded programs, the alphabet of the pattern is given by the reads and writes to the shared storage. We study the complexity of pattern-based verification for multithreaded programs with shared counters and finite variables. While unrestricted verification is undecidable for abstracted multithreaded programs with recursive procedures and PSPACE-complete for abstracted multithreaded while-programs (even without counters), we show that pattern-based verification is NP-complete for both classes, even in the presence of counters. We then conduct a multiparameter analysis to study the complexity of the problem on its three natural parameters (number of threads+counters+variables, maximal size of a thread, size of the pattern) and on two parameters related to thread structure (maximal number of procedures per thread and longest simple path of procedure calls). We present an algorithm that for a fixed number of threads, counters, variables, and pattern size solves the verification problem in st(O(lsp+[log(pr+1)])) time, where st is the maximal size of a thread, pr is the maximal number of procedures per thread, and lsp is the longest simple path of procedure calls.

关键词： Algorithms Languages Verification Reliability concurrent programming context-free languages multithreaded programs safety underapproximation

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