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3. Which Concepts for Concurrent and Parallel Progr. does a VM need to Support?
The answers to Perf consider intuitive optimizations that become possible
with knowledge of full language semantics. For instance, knowledge
about immutability enables constant folding, and taking the semantics of critical
sections into account enables optimizations like lock elision [Rajwar and
Goodman, 2001]. Furthermore, the answers rely on the literature of proposed
implementation strategies that require changes to a VM.
The last categorization criterion is whether the concept is already common
to VMs that are used as multi-language platforms and should be regarded as
prior art (PA). When it is already available to the major multi-language VMs
identified in Sec. 3.1.1.2, i. e., the JVM or CLI, general VM support for the concept
is considered to be feasible and well understood, and therefore, does not
need to be included in further discussion. Only JVM and CLI are considered
here, because these two are specifically designed as multi-language VMs.
PA Is the concept already supported by a VM like the JVM or CLI?
3.2.1.2. Selecting Subjects and Identifying Concepts
The survey of Briot et al. [1998] of concurrent and distributed systems as well
as the survey of Skillicorn and Talia [1998] of parallel models and languages
are the main subjects to identify concurrent and parallel programming concepts.
They provide a broad foundation and an overview over a wide range of
concurrent and parallel programming concepts. Since concurrent and parallel
programming have been investigated for years in the field of logic programming
as well, two surveys for parallel logic programming [De Bosschere, 1997;
Gupta et al., 2001] complement the surveys from the imperative world. However,
since all four surveys are dated and lack coverage of recent work, a
number of languages used in research or industry and selected research papers
from recent years are included as subjects to cover current trends. The
full list of subjects is given in Tab. 3.3.
This survey identifies for each of these subject the basic concurrent and parallel
programming concepts it introduces, i. e., the concepts that are presented
by the paper or provided by the language. For languages, this includes concepts
from the language-level as well as the implementation-level. Note that
the identified concepts abstract necessarily from specific details that vary between
the different subjects. Thus, this analysis does not regard minor variations
of a concept separately. However, this leaves room for different interpretations
of the survey questions. Furthermore, the analysis of subjects such
as C/C++ and Java considers only the core language and standard libraries.
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