Today's shared-memory parallel programming models are complex and error-prone.While many parallel programs are intended to be deterministic, unanticipated thread interleavings can lead to subtle bugs and nondeterministic semantics. In this paper, we demonstrate that a practical
type and effect system
can simplify parallel programming by
guaranteeing deterministic semantics
with modular, compile-time type checking even in a rich, concurrent object-oriented language such as Java. We describe an object-oriented type and effect system that provides several new capabilities over previous systems for expressing deterministic parallel algorithms.We also describe a language called Deterministic Parallel Java (DPJ) that incorporates the new type system features, and we show that a core subset of DPJ is sound. We describe an experimental validation showing thatDPJ can express a wide range of realistic parallel programs; that the new type system features are useful for such programs; and that the parallel programs exhibit good performance gains (coming close to or beating equivalent, nondeterministic multithreaded programs where those are available).
Background
The 2014 Surgeon General’s Report noted that high smoking rates in vulnerable populations such as the homeless have been a persistent public health problem; smoking prevalence among individuals experiencing homelessness exceeds 70%. Historically, service providers for the homeless have not enacted comprehensive tobacco control policies.
Method
We conducted a qualitative study of homeless housing programs in San Francisco. Administrators representing 9 of the city’s 11 homeless service agencies were interviewed to assess institutional smoking-related policies and cessation programs and perceived barriers and receptivity to instituting tobacco control interventions.
Results
Respondents indicated that although most programs had adopted smoke-free grounds and some had eliminated evidence of staff smoking, the smoking status of clients was assessed only when required by funders. None of the programs offered smoking cessation interventions. Most administrators were receptive to adopting policies that would promote a tobacco-free culture; however, they noted that their clients had unique challenges that made traditional smoking cessation programs unfeasible.
Conclusions
Homeless housing programs in San Francisco have not yet adopted a tobacco-free culture. Existing policies were created in response to external mandates, and smoking cessation programs may need to be modified in order to effectively reach clients.
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