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The Delta Debugging project at Software Engineering Chair, Saarland University investigates an
automated debugging approach based on systematic
testing. With Delta Debugging, we can find failure-inducing
circumstances automatically—circumstances such as the
program input, changes to the program code, or program executions.
About Delta Debugging
- Delta Debugging automates the scientific method of
debugging. The basic idea of the scientific method is to
establish a hypothesis on why something does not work. You
test this hypothesis, and you refine or reject it depending on the
test outcome. When debugging, people are doing this all the time.
Manually. Delta Debugging automates this process.
Narrowing down possible failure
- The most exciting application so far is to isolate the entire
cause-effect chain of a failure: "Initially, variable v1 was
x1, thus variable v2 became x2, thus variable v3 became x3 ... and
thus the program failed." This explains failure causes
automatically and effectively, for programs as large as the GNU C
compiler. This paper won the
ACM SIGSOFT Distinguished Paper Award.
- The locations at which a cause-effect chain changes its variables
are actually likely defects. Thus allows us to locate defects that
cause a given failure automatically.
- As a simple application, consider a program that fails when given
some input. With Delta Debugging, you can isolate and minimize the
failure-inducing input automatically. For instance, if your browser
crashes on a 10,000-line WWW page, Delta Debugging can determine the
failure-inducing HTML tag.
- As another application, consider a program and a number of
changes to the program code. After applying the changes, the program
no longer works. With Delta Debugging, you can identify the
failure-inducing changes automatically. Read more...
- Yet another application is the isolation of failure-inducing
executed statements - that is, the events during execution which
were critical for producing the failure. This work is at an early
stage. Read more...
- Further applications are the identification of failure-inducing
schedules (e.g. race conditions due to nondeterministic
behavior) or the isolation of failure-inducing control
statements (i.e. which branches taken were relevant and which
- Isolating Relevant Component Interactions with JINSI. Alessandro Orso, Shrinivas Joshi, Martin Burger, and Andreas Zeller; Proc. 2006 International
Workshop on Dynamic Analysis (WODA 2006), Shanghai,
China, May 2006.
When a component in a large system fails, developers encounter two
problems: (1) reproducing the failure, and (2) investigating the
causes of such a failure. Our JINSI tool lets developers capture and
replay the interactions between a component and its environment, thus
allowing for reproducing the failure at will. In addition, JINSI uses
delta debugging to automatically isolate the subset of the
interactions that is relevant for the failure. In a first study, JINSI
has successfully isolated the relevant interaction of a JAVA
component: "Out of the 32 interactions with the VendingMachine
component, seven interactions suffice to produce the failure."
- Locating Causes of Program
Failures. Holger Cleve and Andreas Zeller; Proc. 27th International
Conference on Software Engineering (ICSE 2005), St. Louis,
Missouri, May 2005.
Which is the defect that causes a software failure? By comparing the
program states of a failing and a passing run, we can identify the
state differences that cause the failure. However, these state
differences can occur all over the program run. Therefore, we focus
in space on those variables and values that are relevant for
the failure, and in time on those moments where cause
transitions occur—moments where new relevant variables begin
being failure causes: “Initially, variable argc was 3;
therefore, at shell_sort(), variable a was 0, and
therefore, the program failed.” In our evaluation, cause
transitions locate the failure-inducing defect twice as well as
the best methods known so far.
- Isolating Cause-Effect
Chains from Computer Programs. Andreas Zeller;
Proc. ACM SIGSOFT 10th International
Symposium on the Foundations of Software Engineering (FSE-10),
Charleston, South Carolina, November 2002.
Consider the execution of a failing program as a sequence of program
states. Each state induces the following state, up to the failure.
Which variables and values of a program state are relevant for the
failure? We show how the Delta Debugging algorithm isolates
the relevant variables and values by systematically narrowing the
state difference between a passing run and a failing run - by
assessing the outcome of altered executions to determine wether a
change in the program state makes a difference in the test outcome.
Applying Delta Debugging to multiple states of the program
automatically reveals the cause-effect chain of the
failure - that is, the variables and values that caused the failure.
In a case study, our prototype implementation successfully narrowed
down the cause-effect chain for a failure of the GNU C compiler:
``Initially, the C program to be compiled contained an addition of
1.0; this caused an addition operator in the intermediate RTL
representation; this caused a cycle in the RTL tree - and this
caused the compiler to crash.''
- Isolating Failure-Inducing
Thread Schedules. Jong-Deok Choi and Andreas Zeller; Proc.
on Software Testing and Analysis (ISSTA 2002), Rome, Italy, July 2002.
Consider a multi-threaded application that occasionally fails due to
non-determinism. Using the DEJAVU capture/replay tool, it is
possible to record the thread schedule and replay the application in
a deterministic way. By systematically narrowing down the
difference between a thread schedule that makes the program pass and
another schedule that makes the program fail, the Delta Debugging
approach can pinpoint the error location automatically - namely, the
location(s) where a thread switch causes the program to fail. In a
case study, Delta Debugging isolated the failure-inducing schedule
difference from 3.8 billion differences in only 50 tests.
Automated Debugging: Are We
Close? Andreas Zeller; IEEE Computer, November 2001.
Debugging is still one of the hardest, yet least systematic activities
of software engineering. The Delta Debugging algorithm isolates
failure causes automatically - by systematically narrowing down
failure-inducing circumstances until a minimal set remains. Delta
Debugging has been applied to isolate failure-inducing program input
(e.g. a HTML page that makes a Web browser fail), failure-inducing
user interaction (e.g. the keystrokes that make a program crash), or
failure-inducing changes to the program code (e.g. after a failing
Delta Debugging is fully automatic; all it requires
is an automated test that detects whether the expected failure is
present or not. The method is introduced using real-life programs with
Generating and testing hypotheses
Simplifying and Isolating
Failure-Inducing Input. Andreas Zeller and Ralf
Transactions on Software Engineering 28(2), February 2002,
Given some test case, a program fails. Which circumstances of the
test case are responsible for the particular failure? The
Delta Debugging algorithm generalizes and simplifies some
failing test case to a minimal test case that still produces
the failure; it also isolates the difference between a
working and a failing test case.
In a case study, the Mozilla web browser crashed after 95 user
actions. Our prototype implementation automatically simplified the
input to 3 relevant user actions. Likewise, it simplified 896 lines
of HTML to the single line that caused the failure. The case study
required 139 automated test runs, or 35 minutes on a 500 MHz PC.
Finding Failure Causes through
Automated Testing. Holger Cleve, Andreas Zeller;
Proc. Fourth International Workshop on Automated Debugging, Munich,
Germany, 28-30 August 2000.
Abstract. A program fails. Under which
circumstances does this failure occur? One single algorithm, the
delta debugging algorithm, suffices to determine these
failure-inducing circumstances. Delta debugging applies the
scientific method of debugging to narrow down the set of
failure-inducing circumstances automatically - circumstances such as
the program input, changes to the program code, or executed
Yesterday, my program
worked. Today, it does not. Why? Andreas Zeller;
Proc. ESEC/FSE 99, Toulouse, France,
September 1999, Vol. 1687 of LNCS, pp. 253-267.
Abstract. Imagine some program and a
number of changes. If none of these changes is applied
(``yesterday''), the program works. If all changes are applied
(``today''), the program does not work. Which change is responsible
for the failure? We present an efficient algorithm that determines the
minimal set of failure-inducing changes. Our delta debugging prototype
tracked down a single failure-inducing change from 178,000 changed GDB
lines within a few hours.
We do our best to make all of our software available to the general public.
Be aware, though, that they are prototypes. Here are some packages you
can play with:
- We are building a set of delta debugging
plug-ins for the Eclipse programming environment.
- The AskIgor debugging
service is a public Web service around an extended HOWCOME
prototype, isolating cause-effect chains from failing Linux programs.
- Igor is also available for
(written in Python + licensed under the GPL)
demonstrator. This demonstrator shows how to isolate cause-effect
chains from computer programs. ZIP archive for Linux PCs.
- DD.py, the Delta Debugging core module, realizes the
Delta Debugging algorithm as a Python class. By providing your own
subclass with its own _test method, you can realize arbitrary
applications. See the tutorial for details.
- XLAB-980917, the last public
snapshot of Marc Vertes' XLAB. This is used for recording and playing
back X user input.
Keep me posted
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<email@example.com> · http://www.st.cs.uni-saarland.de//dd/ · Stand: 2018-04-05 13:40