42,458 research outputs found
Debugging Scandal: The Next Generation
In 1997, the general lack of debugging tools was termed "the debugging scandal". Today, as new languages are emerging to support software evolution, once more debugging support is lagging. The powerful abstractions offered by new languages are compiled away and transformed into complex synthetic structures. Current debugging tools only allow inspection in terms of this complex synthetic structure; they do not support observation of program executions in terms of the original development abstractions. In this position paper, we outline this problem and present two emerging lines of research that ease the burden for debugger implementers and enable developers to debug in terms of development abstractions. For both approaches we identify language-independent debugger components and those that must be implemented for every new language. One approach restores the abstractions by a tool external to the program. The other maintains the abstractions by using a dedicated execution environment, supporting the relevant abstractions. Both approaches have the potential of improving debugging support for new languages. We discuss the advantages and disadvantages of both approaches, outline a combination thereof and also discuss open challenges
Reify Your Collection Queries for Modularity and Speed!
Modularity and efficiency are often contradicting requirements, such that
programers have to trade one for the other. We analyze this dilemma in the
context of programs operating on collections. Performance-critical code using
collections need often to be hand-optimized, leading to non-modular, brittle,
and redundant code. In principle, this dilemma could be avoided by automatic
collection-specific optimizations, such as fusion of collection traversals,
usage of indexing, or reordering of filters. Unfortunately, it is not obvious
how to encode such optimizations in terms of ordinary collection APIs, because
the program operating on the collections is not reified and hence cannot be
analyzed.
We propose SQuOpt, the Scala Query Optimizer--a deep embedding of the Scala
collections API that allows such analyses and optimizations to be defined and
executed within Scala, without relying on external tools or compiler
extensions. SQuOpt provides the same "look and feel" (syntax and static typing
guarantees) as the standard collections API. We evaluate SQuOpt by
re-implementing several code analyses of the Findbugs tool using SQuOpt, show
average speedups of 12x with a maximum of 12800x and hence demonstrate that
SQuOpt can reconcile modularity and efficiency in real-world applications.Comment: 20 page
An LLVM Instrumentation Plug-in for Score-P
Reducing application runtime, scaling parallel applications to higher numbers
of processes/threads, and porting applications to new hardware architectures
are tasks necessary in the software development process. Therefore, developers
have to investigate and understand application runtime behavior. Tools such as
monitoring infrastructures that capture performance relevant data during
application execution assist in this task. The measured data forms the basis
for identifying bottlenecks and optimizing the code. Monitoring infrastructures
need mechanisms to record application activities in order to conduct
measurements. Automatic instrumentation of the source code is the preferred
method in most application scenarios. We introduce a plug-in for the LLVM
infrastructure that enables automatic source code instrumentation at
compile-time. In contrast to available instrumentation mechanisms in
LLVM/Clang, our plug-in can selectively include/exclude individual application
functions. This enables developers to fine-tune the measurement to the required
level of detail while avoiding large runtime overheads due to excessive
instrumentation.Comment: 8 page
Using the DiaSpec design language and compiler to develop robotics systems
A Sense/Compute/Control (SCC) application is one that interacts with the
physical environment. Such applications are pervasive in domains such as
building automation, assisted living, and autonomic computing. Developing an
SCC application is complex because: (1) the implementation must address both
the interaction with the environment and the application logic; (2) any
evolution in the environment must be reflected in the implementation of the
application; (3) correctness is essential, as effects on the physical
environment can have irreversible consequences. The SCC architectural pattern
and the DiaSpec domain-specific design language propose a framework to guide
the design of such applications. From a design description in DiaSpec, the
DiaSpec compiler is capable of generating a programming framework that guides
the developer in implementing the design and that provides runtime support. In
this paper, we report on an experiment using DiaSpec (both the design language
and compiler) to develop a standard robotics application. We discuss the
benefits and problems of using DiaSpec in a robotics setting and present some
changes that would make DiaSpec a better framework in this setting.Comment: DSLRob'11: Domain-Specific Languages and models for ROBotic systems
(2011
Network Virtual Machine (NetVM): A New Architecture for Efficient and Portable Packet Processing Applications
A challenge facing network device designers, besides increasing the speed of network gear, is improving its programmability in order to simplify the implementation of new applications (see for example, active networks, content networking, etc). This paper presents our work on designing and implementing a virtual network processor, called NetVM, which has an instruction set optimized for packet processing applications, i.e., for handling network traffic. Similarly to a Java Virtual Machine that virtualizes a CPU, a NetVM virtualizes a network processor. The NetVM is expected to provide a compatibility layer for networking tasks (e.g., packet filtering, packet counting, string matching) performed by various packet processing applications (firewalls, network monitors, intrusion detectors) so that they can be executed on any network device, ranging from expensive routers to small appliances (e.g. smart phones). Moreover, the NetVM will provide efficient mapping of the elementary functionalities used to realize the above mentioned networking tasks upon specific hardware functional units (e.g., ASICs, FPGAs, and network processing elements) included in special purpose hardware systems possibly deployed to implement network devices
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