This document describes a technique for mining software version archives to identify lines of code that frequently change together between versions (co-changed lines). It presents an example of identifying co-changed lines in two files where the minor version number was changed in both files between versions. The technique aims to help programmers understand how changes in one area of the system can impact other areas.

1. Mining Version Archives
for Co-changed Lines
Tom Zimmermann • Saarland University, Saarbrücken
Sunghun Kim • University of California, Santa Cruz
Andreas Zeller • Saarland University, Saarbrücken
E. James Whitehead, Jr • University of California, Santa Cruz

2. Annotating Lines
Tx12 Tx23 Tx42 Tx79
1: 1: 1: 1:
ADD
2: 2: 2: 2:
3: 3: 3: 3:
4: 4: 4: 4:
5: 5: 5: 5:
CHG DEL
6: 6: 6: 6:
7: 7: 7: 7:
8: 8: 8: 8:
9: 9: 9: 9:
10: 10: 10: 10:
11: 11: 11: 11:
CHG
12: 12: 12: 12:
CHG
13: 13: 13:
14: 14: 14:
15: 15:
16: 16:

3. Annotating Lines
Tx12 Tx23 Tx42 Tx79 Annotation
1: 1: 1: 1: 1: 12
ADD
2: 2: 2: 2: 2: 12
3: 3: 3: 3: 3: 23
4: 4: 4: 4: 4: 23
5: 5: 5: 5: 5: 23
CHG DEL
6: 6: 6: 6: 6: 12
7: 7: 7: 7: 7: 12
8: 8: 8: 8: 8: 12; 23
9: 9: 9: 9: 9: 12; 23
10: 10: 10: 10: 10: 12; 23; 79
11: 11: 11: 11: 11: 12
CHG
12: 12: 12: 12: 12: 12
CHG
13: 13: 13: 13: 12
14: 14: 14: 14: 12
15: 15:
16: 16:

4. Frequently Changed Lines
org.eclipse.jdt.doc.isv/jdtOptions.txt
1: -charset quot;iso-8859-1quot;
2: -sourcepath [...]
3: -d reference/api
4: -classpath @rt@;../org.apache.ant/lib/ant.jar;../org.eclipse.debug.core/@dot;../org.eclipse.compare/@dot;../org.ec
lipse.help/@dot;../org.eclipse.help.ui/@dot;../org.eclipse.core.resources/@dot;../org.eclipse.core.runtime/@dot;..
/org.eclipse.core.filebuffers/@dot;../org.eclipse.core.expressions/@dot;../org.eclipse.swt.win32.win32.x86/@dot;.
./org.eclipse.ui/@dot;../org.eclipse.jdt.debug/jdi.jar;../org.eclipse.debug.ui/@dot;../org.eclipse.search/@dot;../org.e
clipse.jface/@dot;../org.eclipse.jface.text/@dot;../org.eclipse.text/@dot;../org.eclipse.ui.editors/@dot;../org.eclips
e.ui.views/@dot;../org.eclipse.ui.workbench/@dot;../org.eclipse.ui.workbench.texteditor/@dot;../org.eclipse.core
.variables/@dot;../org.eclipse.ui.ide/@dot;../org.eclipse.jdt.junit/@dot;../org.eclipse.osgi/@dot;../org.eclipse.osgi.s
ervices/@dot;../org.eclipse.osgi.util/@dot;../org.eclipse.ui.forms/@dot;../org.eclipse.core.commands/@dot;../org.
eclipse.ltk.core.refactoring/@dot;../org.eclipse.ltk.ui.refactoring/@dot;../org.eclipse.core.filesystem/@dot;../org.e
clipse.core.jobs/@dot;../org.eclipse.equinox.registry/@dot;../org.eclipse.equinox.common/@dot;../org.eclipse.co
re.contenttype/@dot;../org.eclipse.equinox.preferences/@dot;../org.eclipse.equinox.supplement/@dot;../org.ecli
pse.core.runtime.content/@dot;../org.eclipse.core.runtime.jobs/@dot;../org.eclipse.core.runtime.preferences/@
dot
5: -breakiterator
6: -use

5. Frequently Changed Lines
org.eclipse.jdt.doc.isv/jdtOptions.txt
1: -charset quot;iso-8859-1quot;
2: -sourcepath [...]
3: -d reference/api
4: -classpath @rt@;../org.apache.ant/lib/ant.jar;../org.eclipse.debug.core/@dot;../org.eclipse.compare/@dot;../org.ec
lipse.help/@dot;../org.eclipse.help.ui/@dot;../org.eclipse.core.resources/@dot;../org.eclipse.core.runtime/@dot;..
/org.eclipse.core.filebuffers/@dot;../org.eclipse.core.expressions/@dot;../org.eclipse.swt.win32.win32.x86/@dot;.
ED
./org.eclipse.ui/@dot;../org.eclipse.jdt.debug/jdi.jar;../org.eclipse.debug.ui/@dot;../org.eclipse.search/@dot;../org.e
NG
HA
clipse.jface/@dot;../org.eclipse.jface.text/@dot;../org.eclipse.text/@dot;../org.eclipse.ui.editors/@dot;../org.eclips
C
e.ui.views/@dot;../org.eclipse.ui.workbench/@dot;../org.eclipse.ui.workbench.texteditor/@dot;../org.eclipse.core
.variables/@dot;../org.eclipse.ui.ide/@dot;../org.eclipse.jdt.junit/@dot;../org.eclipse.osgi/@dot;../org.eclipse.osgi.s
ES
TIM
ervices/@dot;../org.eclipse.osgi.util/@dot;../org.eclipse.ui.forms/@dot;../org.eclipse.core.commands/@dot;../org.
28
eclipse.ltk.core.refactoring/@dot;../org.eclipse.ltk.ui.refactoring/@dot;../org.eclipse.core.filesystem/@dot;../org.e
clipse.core.jobs/@dot;../org.eclipse.equinox.registry/@dot;../org.eclipse.equinox.common/@dot;../org.eclipse.co
re.contenttype/@dot;../org.eclipse.equinox.preferences/@dot;../org.eclipse.equinox.supplement/@dot;../org.ecli
pse.core.runtime.content/@dot;../org.eclipse.core.runtime.jobs/@dot;../org.eclipse.core.runtime.preferences/@
dot
5: -breakiterator
6: -use

6. Co-change on Lines
j2me/Library.java
...
25: static int MINOR_VERSION = 215;
...
version.txt
1: version 3.215
j2se/Library.java
...
25: static int MINOR_VERSION = 215;
...

7. Co-change on Lines
j2me/Library.java
...
25: static int MINOR_VERSION = 215;
ED
...
NG
HA
C
ES
version.txt
TIM
71
1
1: version 3.215
ER
TH
GE
TO
j2se/Library.java
...
25: static int MINOR_VERSION = 215;
...