Dynamic Event Generation for Runtime Checking Using the JDI

Dynamic Event Generation for Runtime Checking Using the JDI

MARK BRÖRKENSOFFIS, GERMANY

Introduction Jassda Performance Summary

Dynamic Event Generation for Runtime Checking Using the JDI

Introduction Jassda Performance Summary

• Motivation

• Runtime Checking

• Architecture

• JDI

• Modules

• Logger

• Trace Checker

• Bubblesort -

Benchmark

• Conclusion

• Future Work

overview

Dynamic Event Generation for Runtime Checking Using the JDI

motivation

Software systems are getting more complex

Introduction Jassda Performance Summary

Formal methods are being researched to prove thecorrectness of a system

Successfully applied to domain specific areas in software engineering

Often restricted to experts

Dynamic Event Generation for Runtime Checking Using the JDI

runtime checking: design by contract

Introduction Jassda Performance Summary

client supplier

• Proposed by Bertrand Meyer for Eiffel• For Java: iContract, jContractor, Runtime Checker of

JML, Jass• Code is inserted for checking of assertions• Sequence of method invocations can’t be checked

Dynamic Event Generation for Runtime Checking Using the JDI

Introduction Jassda Performance Summary

init

start

stop

destroy

Applet

• Track the execution of an application• Decide, whether the current trace is correct

runtime checking

Dynamic Event Generation for Runtime Checking Using the JDI

Jassda – Java with Assertions Debugger Architecture

Introduction Jassda Performance Summary

LoggerTrace-

Checker

GUI Broker other corecomponents

Debuggee(1)

Debuggee(n)

JDI

core

jass

da

modules

Dynamic Event Generation for Runtime Checking Using the JDI

JDI - Features

Introduction Jassda Performance Summary

• remote access

• introspective access to a running virtual machine– loaded classes and their

variables, methods– bytecode of methods

• explicit control over a virtual machine's execution– suspend and resume threads– set breakpoints and

watchpoints– notification of

• method invocation• method termination• exceptions• class loading• vm died• breakpoint reached• variable read/changed

Dynamic Event Generation for Runtime Checking Using the JDI

JDI – Problems and Solutions

Introduction Jassda Performance Summary

For full functionality code has to be compiled with debug information

Add generic debug information in class files using the Byte Code Engineering Library (BCEL)

Direct access to return values of methods missing

Write return value into local variable and set breakpoint before method termination

Solution

Solution

Dynamic Event Generation for Runtime Checking Using the JDI

Configuraion of Event Generation

Introduction Jassda Performance Summary

modulebrokerdebuggee

get event types

get all classes

listens on event?

configure events

resume

{Applet}

{begin, end}

analyse class{init, start, ....}

true

suspend

configure basic events

Dynamic Event Generation for Runtime Checking Using the JDI

Module: Logger

Introduction Jassda Performance Summary

• Writes sequence of events into a file

• The set of events can be customized in an XML-based configuration-file

Dynamic Event Generation for Runtime Checking Using the JDI

Module: Logger

Introduction Jassda Performance Summary

<?xml version="1.0" encoding="UTF-8"?><logger> <file name="sequence.log"/> <event> <template>%method%(%arguments%) = %returnvalue%</template> </event> <include> <eventset class="de.jassda.core.event.GenericSet" field="class" argument="de.jassda.examples.*"/> </include> <exclude> <eventset class="de.jassda.core.event.GenericSet" field="class" argument=“de.jassda.examples.test.*"/> </exclude></logger>

Dynamic Event Generation for Runtime Checking Using the JDI

Module: TraceChecker

Introduction Jassda Performance Summary

• Check sequence of events against CSP-like specification (CSPjassda)

Dynamic Event Generation for Runtime Checking Using the JDI

TraceChecker: CSPjassda

Introduction Jassda Performance Summary

eventset applet { instanceof="java.applet.Applet" }eventset init { method="init" } .....

applets() { ||i:[instance] @ applet.i.init.begin -> applet.i.init.end -> appletrun(i)}

appletrun(i) { ( applet.i.start.begin -> applet.i.start.end -> applet.i.stop.begin -> applet.i.stop.end -> appletrun(i) ) [] appletdestroy(i)}appletdestroy(inst) { applet.inst.destroy.begin -> applet.inst.destroy.end -> STOP}

Alphabet: {applet.init.begin, applet.init.end, applet.start.begin, applet.start.end, applet.stop.begin, applet.stop.end, applet.destroy.begin, applet.destroy,end}

Dynamic Event Generation for Runtime Checking Using the JDI

Jassda: GUI

Introduction Jassda Performance Summary

Dynamic Event Generation for Runtime Checking Using the JDI

Performance

Introduction Jassda Performance Summary

Bubblesort • sort 10000 numbers• 2 implementations:

• 1 method invocation• 10001 method invocations

Platform• Windows 2000• Pentium 1.2GHz• jdk1.3 classic• jdk1.3 hotspot • jdk1.4

Scenarios• standalone• debug-mode enabled• jassda tool attached

1

10

100

1000

10000

1 method invocation

10001 method invocations

jdk1.3classic

jdk1.3hotspot

jdk1.4

seconds

Dynamic Event Generation for Runtime Checking Using the JDI

Conclusion

Introduction Jassda Performance Summary

• Using the JDI is a viable method to trace the execution of (distributed) Java applications

• No or little modification on code is necessary

• Jassda works fine for limited number of events

• The set of events that are generated can be changed during the debug run

Dynamic Event Generation for Runtime Checking Using the JDI

Future Work

Introduction Jassda Performance Summary

• Improve jassda– performance

– usability of GUI

– add modules e.g DbC

• Improve CSPjassda

• Case studies: expressiveness of CSPjassda, scalability and overhead of debug architecture

Dynamic Event Generation for Runtime Checking Using the JDI

http://jassda.sourceforge.net

Introduction Jassda Performance Summary