Debugging mixed‐environment programs with Blink

Programmers build large‐scale systems with multiple languages to leverage legacy code and languages best suited to their problems. For instance, the same program may use Java for ease of programming and C to interface with the operating system. These programs pose significant debugging challenges, because programmers need to understand and control code across languages, which often execute in different environments. Unfortunately, traditional multilingual debuggers require a single execution environment. This paper presents a novel composition approach to building portable mixed‐environment debuggers, in which an intermediate agent interposes on language transitions, controlling and reusing single‐environment debuggers. We implement debugger composition in Blink, a debugger for Java, C, and the Jeannie programming language. We show that Blink is (i) simple: it requires modest amounts of new code; (ii) portable: it supports multiple Java virtual machines, C compilers, operating systems, and component debuggers; and (iii) powerful: composition eases debugging, while supporting new mixed‐language expression evaluation and Java native interface bug diagnostics. To demonstrate the generality of interposition, we build prototypes and demonstrate debugger language transitions with C for five of six other languages (Caml, Common Lisp, C#, Perl 5, Python, and Ruby) without modifications to their debuggers. Using real‐world case studies, we show that diagnosing language interface errors require prior single‐environment debuggers to restart execution multiple times, whereas Blink directly diagnoses them with one execution. Copyright © 2014 John Wiley & Sons, Ltd.     

A database model of debugging

Debugging a program can be viewed as performing queries and updates on a database that contains program source information as well as the state of the executing program. This approach integrates the facilities of a traditional debugger into a programming environment by providing access to runtime information through normal database query operations. We are building a programming environment in which all program information is stored in a relational database system. This system will include capabilities to provide the programmer a simple yet powerful mechanism for describing debugging requests.     

Retargetability and Extensibility in a Parallel Debugger

This paper describes the design and implementation ofPanorama, a parallel debugger for MIMD message-passing computers. Programmers can readily adapt Panorama to new parallel platforms and extended it to include their ownviewsof a target program. The system comes with three built-in graphical program views, and it also includes a software tool to help programmers design and implement new views. Panorama avoids detailed dependence on target architectures by using thebase debuggersupplied by each hardware vendor to carry out low-level debugging tasks such as setting breakpoints and examining data. Since the interfaces and capabilities of base debuggers vary, we have developed a strategy that models interactions between Panorama and base debuggers. The model separates general-purpose code from the special-case functions that handle specific debugger characteristics. The resulting system is easy to adapt and free from the clutter of conditionally-executed, special-case code.     

Relative Debugging of Automatically Parallelized Programs

We describe a system that simplifies the process of debugging programs produced by computer-aided parallelization tools. The system uses relative debugging techniques to compare serial and parallel executions in order to show where the computations begin to differ. If the original serial code is correct, errors due to parallelization will be isolated by the comparison.One of the primary goals of the system is to minimize the effort required of the user. To that end, the debugging system uses information produced by the parallelization tool to drive the comparison process. In particular, the debugging system relies on the parallelization tool to provide information about where variables may have been modified and how arrays are distributed across multiple processes. User effort is also reduced through the use of dynamic instrumentation. This allows us to modify the program execution without changing the way the user builds the executable. The use of dynamic instrumentation also permits us to compare the executions in a fine-grained fashion and only involve the debugger when a difference has been detected. This reduces the overhead of executing instrumentation.     

Distributed debugging for mobile networks

Debuggers are an integral part, albeit often neglected, of the development of distributed applications. Ambient-oriented programming (AmOP) is a distributed paradigm for applications running on mobile ad hoc networks. In AmOP the complexity of programming in a distributed setting is married with the network fragility and open topology of mobile applications. To our knowledge, there is no debugging approach that tackles both these issues. In this paper we argue that a novel kind of distributed debugger that we term an ambient-oriented debugger, is required. We present REME-D (read as remedy), an online ambient-oriented debugger that integrates techniques from distributed debugging (event-based debugging, message breakpoints) and proposes facilities to deal with ad hoc, fragile networks – epidemic debugging, and support for frequent disconnections.     

一个基于Eclipse的通用Java程序插桩工具

插桩技术作为一种有效理解程序动态行为的手段,已经被广泛应用于程序分析、测试和验证中。然而,由于缺少通用的插桩工具,各种具体的应用往往需要从头开发特定的插桩程序,存在着大量的重复性工作。此外,由于在原始程序中插入了大量额外代码,致使调试过程变得更加复杂和困难。针对这些问题,提出了一个基于Eclipse的通用Java代码插桩工具,即通过规则定义匹配程序的执行点,从而定制针对各种分析、测试和验证插桩需求的支持。通过对插桩代码片段的显式/隐式切换实现其可见性管理,从而确保程序的理解和调试过程不受插桩代码影响。通过使用该工具,可以更好地将插桩技术应用于Java程序开发中。     

开源跨平台的图像可视化调试器设计

目的 在调试C/C++图像处理程序时,如何以可视化的形式观察被调试程序中的图像变量,对于调试过程尤为关键。目前尚未有跨多操作系统平台的图像可视化调试器可供使用,该款开源跨平台的图像可视化调试器的设计与实现弥补了此领域的不足。方法 利用GDB(GNU debugger)调试器的Python接口,将被调试程序中的图像变量对应的内存字节序列转化成Python下的2维数组,并采用Matplotlib库加以显示,整个图像显示线程独立于GDB的文本字符交互主线程。结果 在Windows、Linux、Mac系统中分别进行实验,均可实现图像变量的显示、缩放、平移、像素数值查看、保存等多种功能,并使得GDB的命令行保持非阻塞模式运行。结论 开源跨平台的图像可视化调试器的设计,满足了不同操作系统平台下图像程序的开发调试需求,弥补了当前GDB调试图像程序功能的不足,提高了图像处理程序的开发和调试效率。     

Java卡调试平台的研究及实现

从计算机语言源代码级调试的一般性原理和概念入手,深入分析了Java卡规范和Java平台调试体系规范,提供了一个合理的Java仁调试平台设计方案。此外,文章还详细描述了调试平台实施所涉及到的要点,包括运行时调试信息的组织方式和使用方法、断点实现技术、单步调试实现技术等。实验结果表明,该调试平台设计方案是可行的。     

基于方舟Ⅲ的可移植监测程序设计

针对已有嵌入式调试程序不支持动态设置断点的缺点,提出一种可移植的监测调试程序。基于国产新型高性能处理器方舟Ⅲ,阐述其监测程序设计过程,调试并实现方舟Ⅲ平台的引导装载程序,实验结果证明该设计具有较好的可移植性和实用价值。     

A debugger for concurrent programs

This paper reports on an experimental debugger for concurrent programs. Design objectives include a showing of greatest usefulness when dealing with multiprocess interactions, creation of a simplified more approachable interface for programmers, allowance for the systematic organization (and limitation) of debugging information by programmers, reflection of a natural view of concurrency, and portability. The design responds to a perceived need for debugging techniques applicable in systems of concurrent, communicating, asynchronous processes. During debugging sessions, a user is able to dynamically explore interprocess synchronization points, parallel actions and deadlock situations. The programmer interface is based on a transparent window multiplexer providing a set of windows for each concurrent process. The window manager interactively maps interesting windows to programmer-specified viewscreen locations, while relegating temporarily uninteresting windows to the background. In implementing a debugger for concurrent programs, a principal concern is the probe effect, or the possibility that the debugger itself masks synchronization errors in the program being debugged. For the examples explored, the probe effect was not observed to limit the localization of implanted synchronization errors.     

一种具有快速条件断点的并行程序调试器

快速条件断点是高性能并行程序调试器中进程控制必备的功能之一.分析了快速条件断点基本原理以及快速条件断点设计中需要考虑的代码生成、代码插装和源程序对应等问题.并针对上述问题,提出了预编译与运行时编译结合的代码生成方式、动态代码插装、源断点标识技术等解决方案.利用经过改进的动态补丁码工具Dyninst,设计实现了并行程序调试器XBUSTER,并实现了快速条件断点这一重要功能.测试表明,XBUSTER的执行效率比传统条件断点高.与现有的基于动态插装的系统,如Ceder,ldb和Dyner相比,XBUSTER具有功能性强、可移植性好等鲜明特点.     

Sequential debugging at a high level of abstraction

Efforts to build a better mousetrap for bugs in sequential programs are described. The resulting debugger, called Dalek, is intended to remedy limitations in conventional execution harnesses. Beyond the simple `stop and look' features offered by typical breakpoint debuggers, Dalek offers a rich control and query language. Dalek's linguistic capabilities for treating sequences of program events offer an improvement over scratch paper as a compensatory technology for human memory limitations. Example applications are given. The very interactive, dynamic style of debugging encouraged by Dalek is discussed     

Exact and Portable Profiling for the JVM Using Bytecode Instruction Counting

This paper presents a novel profiling approach, which is entirely based on program transformation techniques in order to enable exact profiling, preserving complete call stacks, method invocation counters, and bytecode instruction counters. We exploit the number of executed bytecode instructions as profiling metric, which has several advantages, such as making the instrumentation entirely portable and generating reproducible profiles. These ideas have been implemented as the JP tool. It provides a small and flexible API to write portable profiling agents in pure Java, which are periodically activated to process the collected profiling information. Performance measurements point out that JP causes significantly less overhead than a prevailing tool for the exact profiling of Java code.     

A debugger for Ada tasking

The capabilities needed in an Ada debugger are discussed in light of the language's tasking constructs, and the design for a debugger is presented which operates in concert with a single-processor Ada interpreter. This debugger design demonstrates the extensions to sequential debugging techniques that are necessary to handle concurrency, and shows that significant debugging functionality can be provided even without the inclusion of automatic error diagnosis methods. The issues considered include isolation of effects and display of the full dynamic execution status, both of which are essential to diagnosis of concurrent programs     

曙光机群系统并行调试器的设计与实现

介绍了为曙光机群系统设计实现的并行调试器DCDB。DCDB同时支持调试MPI或PVM、C或Fortran的并行应用程序，实现了记录／重放并行调试功能，支持循环调试，解决了并行调试时并行程序的不确定性问题。DCDB采用Client／server／Client结构，具有友好的图形用户界面，系统主要采用Java语言开发，具有良好的可移植性和可扩展性。     

JP2: Call-site aware calling context profiling for the Java Virtual Machine

Calling context profiling fulfills programmers’ information needs to obtain a complete picture of a program’s inter- and intra-procedural control flow, which are important for workload characterization, debugging, profiling, program comprehension, and reverse engineering. Many existing calling context profilers for Java, however, resort to sampling or other incomplete instrumentation techniques; thus, they collect incomplete profiles only. In this article we present JP2, a new calling context profiler for the Java Virtual Machine, which collects profiles that are not only complete but also call-site aware; that is, JP2 is able to distinguish between multiple call sites within a single method. JP2 supports selective profiling of the dynamic extent of chosen methods and supports profiling of native method invocations. Moreover, produced profiles contain execution statistics at the level of individual basic blocks of code, thereby preserving the intra-procedural control flow of the profiled applications. We rigorously evaluate the overhead incurred by JP2. This overhead is acceptable in tasks such as workload characterization. JP2 is freely available under an Open Source license.     

Guard: A Relative Debugger

A significant amount of software development is evolutionary, involving the modification of already existing programs. To a large extent, the modified programs produce the same results as the original program. This similarity between the original program and the development program is utilized by relative debugging. Relative debugging is a new concept that enables the user to compare the execution of two programs by specifying the expected correspondences between their states. A relative debugger concurrently executes the programs, verifies the correspondences, and reports any differences found. We describe our novel debugger, called Guard, and its relative debugging capabilities. Guard is implemented by using our library of debugging routines, called Dynascope, which provides debugging primitives in heterogeneous networked environments. To demonstrate the capacity of Guard for debugging in heterogeneous environments, we describe an experiment in which the execution of two programs is compared across Internet. The programs are written in different programming languages and executing on different computing platforms. © 1997 by John Wiley & Sons, Ltd.     

基于曙光5000并行机的远程并行调试器

并行调试对并行程序开发非常重要,然而传统的远程并行调试方式是采用登录(telnet)命令通过命令行的文本界面进行,非常繁杂。本文介绍了为曙光3000系统设计实现的远程并行调试器RPB(Remote Parallel Debugger)。RPB实现了完全并行调试等功能,并且具备图形用户界面,用户界面采用Java语言和Swing工具包实现,具备平台独立的特点。RPB采用客户端/服务器模式,客户端和服务器之间的通信采用当今流行的CORBA中间件技术。RPB支持通过局域网或广域网远程调试并行机上的程序,屏蔽了客户平台的差异和并行机地理位置上的差异,因而大大提高了并行机的好用性。     

Microprocessor debugging techniques and their application in debugger design

Every microprocessor-based system needs powerful debugging tools. Debugging power strongly depends on a mechanism of control exchange between the debugger and an application program. Several implementation methods of such a mechanism are briefly described and compared in this paper. It is shown that conditional breakpoints facilitate a semantics-oriented approach to program debugging. Some debugging techniques derived from elementary control-exchange mechanisms are proposed. Most of the techniques discussed are implemented in the MD-86 debugger designed for the Intel 8086 microprocessor. The debugger itself is also briefly described.