here - Stefan-Marr.de

3. Which Concepts for Concurrent and Parallel Progr. does a VM need to Support?
namic [Thalinger and Rose, 2010] or partial evaluation [Shali and Cook, 2011]
can reduce that overhead by enabling optimization of reflective calls.
Ownership The notion of object ownership is used in a number of concepts
such as Clojure agents, actors, and CSP to define policies that distinguish
between entities that access an object. The implementation of ownership in
a library would require an extension of every object to keep track of its
owner. Runtime support in the memory management system could optimize
the memory overhead by keeping track of the owner implicitly for instance
by splitting the heap in regions that can belong to different owners. Similar
optimizations have been proposed to keep track of meta data for garbage
collection, for instance whether objects contain pointers.[Jones et al., 2011]
Vector Operations VM support for vector operations enables efficient dataparallel
processing of homogenous data vectors. However, they are not yet
widely available in VM instruction sets, even though some argue that it would
provide performance benefits [Parri et al., 2011].
Conclusion From our perspective, the discussed concepts can benefit from
a wide range of different optimizations. The most notable commonality is
that they could benefit from VM infrastructure that provides feedback for
adaptive optimizations. This includes information on high-level communication
behavior, order of data accesses to high-level data structures, information
about low-level data access frequencies, and access to execution profiling data.
Furthermore, it would be beneficial to have a VM interface to inspect and manipulate
the runtime stack, control heap layout, and the location of objects.
Most of these optimizations would rely on a common access to the JIT
compiler and could benefit from solutions such as Graal [Würthinger, 2011].
However, it seems likely that they would also require a significant amount of
infrastructure to be added to a VM that is specific to a single programming
concept.
To conclude, these concepts can benefit from advanced infrastructure for
dynamic optimizations and the corresponding facilities for runtime feedback
and monitoring.
Enforcement of Semantics The following concepts require VM support for
enforcing correct semantics. Some of then could also show from improved
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