Polkadot JAM Slides - Token2049 - By Dr. Gavin Wood
When do changes induce fixes?
1. When
Do Changes Induce Fixes?
On Fridays.
Jacek Śliwerski, Thomas Zimmermann, Andreas Zeller
Saarland University
2. The Risk of Change
Which changes go wrong?
How do we find such “bad” changes?
What can we do with them?
Idea:
combine bug databases + version archives
=> locate fix-inducing changes
3. The Risk of Change
Which changes go wrong?
How do we find such “bad” changes?
What can we do with them?
Idea:
combine bug databases + version archives
=> locate fix-inducing changes
4. Fix-Inducing Changes
Fix-Inducing Changes are
Changes that lead to problems as
indicated by later fixes.
Later:
Example:
... ...
if (foo==null) { if (foo!=null) {
foo.bar(); foo.bar();
FIX-INDUCING FIX
10. Large Transactions
are Risky
Average Number of Changed Files
Bug- Not Bug-
All
Inducing Inducing
Fix
Not a Fix
All 3.52
ECLIPSE, for MOZILLA the average is 3.58.
11. Large Transactions
are Risky
Average Number of Changed Files
Bug- Not Bug-
All
Inducing Inducing
Fix 2.73
Not a Fix 3.81
All 3.52
ECLIPSE, for MOZILLA the other way round.
12. Large Transactions
are Risky
Average Number of Changed Files
Bug- Not Bug-
All
Inducing Inducing
Fix 2.73
Not a Fix 3.81
All 7.49 2.61 3.52
ECLIPSE, for MOZILLA the same tendency.
13. Large Transactions
are Risky
Average Number of Changed Files
Bug- Not Bug-
All
Inducing Inducing
Fix 3.82 2.08 2.73
Not a Fix 11.30 2.77 3.81
All 7.49 2.61 3.52
ECLIPSE, for MOZILLA a different distribution.
14. Fridays are Risky,
Tuesdays are not ;-)
Frequency
11.3%
Monday 18.4%
20.9% of all changes
10.4%
Tuesday
on Tuesday are fixes,
20.9%
11.1%
10.4% induce bugs.
Wednesday 20.0%
12.1%
Thursday 22.3%
12.2%
Friday 24.0%
11.7%
Saturday 14.7%
11.6%
Sunday 16.9%
0% 5% 10% 15% 20% 25% 30% 35% 40%
Fixes
ECLIPSE
Bug-Inducing Changes
15. Fixes are very Risky
Likelihood
8.2%
Monday 25.1%
that a Change
7.1%
Tuesday 22.9%
is Bug-Inducing
8.1%
Wednesday 23.3%
22.9% of all fixes on
8.8%
Thursday
Tuesday induce bugs,
23.5%
only 7.1% of changes
8.7%
Friday 23.2%
for new features do.
8.4%
Saturday 30.3%
8.6%
Sunday 26.4%
0% 5% 10% 15% 20% 25% 30% 35% 40%
ECLIPSE Fixes New Features, Refactoring
16. Is MOZILLA broken?
Fix transactions are larger than regular
transactions (4.39 vs 3.05 files).
48.5% of all revisions are fixes,
41.5% induce later bugs.
A fix induces in 45.2% a later bugs,
regular changes in “only” 38.1%.
17. For earthquakes and crime rates...
Risk depends on Locations
The same with risk of changes!
18. resolveClasspath()
/* (non-Javadoc)
* @see org.eclipse.jdt.launching.IRuntimeClasspathProvider#resolveClasspath
* (org.eclipse.jdt.launching.IRuntimeClasspathEntry[], org.eclipse.debug.core.ILaunchConfiguration)
*/
public IRuntimeClasspathEntry[] resolveClasspath(IRuntimeClasspathEntry[] entries, ILaunchConfiguration configuration)
throws CoreException {
List all = new ArrayList(entries.length);
for (int i = 0; i < entries.length; i++) {
switch (entries[i].getType()) {
case IRuntimeClasspathEntry.PROJECT:
// a project resolves to itself for source lookup (rather than the class file output locations)
all.add(entries[i]);
break;
9 changes,
case IRuntimeClasspathEntry.OTHER:
IRuntimeClasspathEntry2 entry = (IRuntimeClasspathEntry2)entries[i];
if (entry.getTypeId().equals(DefaultProjectClasspathEntry.TYPE_ID)) {
all of them fixes
// add the resolved children of the project
IRuntimeClasspathEntry[] children = entry.getRuntimeClasspathEntries(configuration);
8 bug-inducing changes
IRuntimeClasspathEntry[] res = JavaRuntime.resolveSourceLookupPath(children, configuration);
for (int j = 0; j < res.length; j++) {
all.add(res[j]);
one re-implementation
}
}
break;
default:
IRuntimeClasspathEntry[] resolved =JavaRuntime.resolveRuntimeClasspathEntry(entries[i], configuration);
for (int j = 0; j < resolved.length; j++) {
all.add(resolved[j]);
}
break;
}
}
return (IRuntimeClasspathEntry[])all.toArray(new IRuntimeClasspathEntry[all.size()]);
}
22. Conclusion
Fix- and Bug-inducing changes are an
measure for (past) risk.
We make this risk visible for developers.
HATARI will be released in August 2005
http://www.st.cs.uni-sb.de/softevo/
Until then: Don’t program on Fridays! ;-)
