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3.2. A Survey of Parallel and Concurrent Programming Concepts
3.2.3. Threats to Validity
For the validity of the conclusions drawn from this survey, two of its properties
are of major interest: completeness and correctness. The completeness of this
study cannot be guaranteed since it did not cover all existing literature in the
field. Even if it would have covered all known literature, it would still suffer
from the completeness problem since an analysis requires manual work
in which certain concepts could be overlooked. However, since this study is
based on existing surveys and is complemented with programming languages
and a wide range of recent work, it covers a significant range of concepts and
includes all major trends.
The correctness of this survey might be reduced by the subsumption of concepts,
because relevant details may have been ignored that could have yielded
additional problems that need to be tackled by a VM. However, since the discarded
details are most likely specific to a single concept, they would not have
yielded problems that are as general as the ones already discussed in this survey.
Another aspect of the correctness of the results is their consistency with
the discussion in Sec. 3.1. To prevent such consistency issues, the data for the
survey is recorded in a machine readable format. Appendix A.2 details the
used templates for the survey and gives the full list of concepts identified for
each subject. By using a machine readable notation, it was possible to check
the consistency between the two surveys automatically. For instance, the automation
includes a cross-check of the assessment of the different surveys on
whether a concept is supported by a VM, and whether a library implementation
is possible. Thus, consistency between concepts and their implementation
and implementability is given between the two surveys.
3.2.4. Summary
This survey discusses a wide range of concepts for concurrent and parallel
programming. For each concept, it answers the question of whether the concept’s
semantics benefit from an enforcement in the VM and whether its performance
could benefit significantly from VM support.
A flexible optimization infrastructure and monitoring facilities can be beneficial
for performance. The first conclusion is that the various concepts
would benefit from a wide range of different optimizations. They all could
benefit from access to the JIT compiler infrastructure to improve optimization.
However, to use it properly they would require additional mechanisms
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