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3. Which Concepts for Concurrent and Parallel Progr. does a VM need to Support?
3.1. VM Support for Concurrent and Parallel
Programming
The goal of this section is to investigate the state of the art in VM support
for concurrent and parallel programming, in order to determine the requirements
for multi-language VMs. To this end, the survey identifies for thirteen
VMswhich concepts they support and how the VMs expose them. First, this
section details the survey design, i. e., the questions to be answered for each
VM, the VMs to be discussed, and the survey approach to be taken. Then
it categorizes the VMs based on the taxonomy used in Sec. 2.4.1 and reports
on the support they provide. Finally, it discusses the threats to validity and
presents the conclusions.
The main conclusion is that currently most VMs support only one or two
categories of concurrent programming concepts as part of the VM. Moreover,
the analyzed VMs support parallel programming in libraries only. Thus, the
vision of multi-language VMs that offer support for a wide range of different
approaches to concurrent and parallel programming is as yet not supported.
3.1.1. Survey Design
The survey is designed to answer the following question: How do today’s VMs
support parallel and concurrent programming?
Following the goal of this dissertation, this survey focuses on VMs that are
used as multi-language VMs, i. e., VMs that have been designed as platforms
for multiple languages or are contemporary targets for multiple language
implementations. To complement these VMs, the survey includes a number
of high-level language VMs that provide support for concurrent and parallel
programming concepts or are known for contributions to VM implementation
techniques.
3.1.1.1. Survey Questions
To focus and standardize the survey, the following concrete questions are
answered for each survey subject, i. e., VM:
Which concepts are supported by the language runtime system, i. e., VM?
How are the supported concepts exposed by the VM?
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