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From Igor Wiese <igor.wi...@gmail.com>
Subject Can you help us Hbase Community
Date Tue, 15 Dec 2015 12:06:46 GMT
Hi, Hbase Community.

My name is Igor Wiese, phd Student from Brazil. I sent an email a week
ago about my research. We received some visit to inspect the results
but any feedback was provided.

I am investigating two important questions: What makes two files
change together? Can we predict when they are going to co-change

I've tried to investigate this question on the Hbase project. I've
collected data from issue reports, discussions and commits and using
some machine learning techniques to build a prediction model.

I collected a total of 8492 commits in which a pair of files changed
together and could correctly predict 71% commits. These were the most
useful information for predicting co-changes of files:

- sum of number of lines of code added, modified and removed,

- number of words used to describe and discuss the issues,

- median value of closeness, a social network measure  obtained from
issue comments,

- median value of effective size, a social network measure obtained
from issue comments, and

-  median value of hierarchy, a social network measure obtained from
issue comments.

To illustrate, consider the following example from our analysis. For
release 1.1, the files "util/HBaseFsck.java" and
"hbase/util/HBaseFsckRepair.java" changed together in 13 commits. In
another 40 commits, only the first file changed, but not the second.
Collecting contextual information for each commit made to first file
in previous release, we were able to predict 9 commits in which both
files changed together in release 1.1, and we only issued two false
positives and two wrong predictions. For this pair of files, the most
important contextual information was the number of developers that
commented in an each issue and the social network metric (efficiency)
obtained from issue comments.

- Do these results surprise you? Can you think in any explanation for
the results?

- Do you think that our rate of prediction is good enough to be used
for building tool support for the software community?

- Do you have any suggestion on what can be done to improve the change

You can visit a webpage to inspect the results in details:

All the best,
Igor Wiese

Phd Candidate

Igor Scaliante Wiese
PhD Candidate - Computer Science @ IME/USP
Faculty in Dept. of Computing at Universidade Tecnológica Federal do Paraná

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