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from the logs and replaced with standardized text. We refer to the process of |
enforcing these requirements and delineating the log into events as |
the \emph{abstraction} step. This enables SBLD to treat events |
like ``2019-04-05 19:19:22.441 CEST: Alice calls Bob'' and ``2019-04-07 |
13:12:11.337 CEST: Alice calls Bob'' as two instances of the same |
generic event "Alice calls Bob". The appropriate degree of abstraction |
and how to meaningfully delineate a log will be context-dependent |
and thus we require the user to perform these steps before using SBLD. |
In the current paper we use an abstraction mechanism |
and dataset generously provided by \CiscoNorway{our industrial partner}. |
\renewcommand{\Ncf}{\ensuremath{\text{N}_\text{FI}}} % |
\renewcommand{\Nuf}{\ensuremath{\text{N}_\text{FE}}} % |
\renewcommand{\Ncs}{\ensuremath{\text{N}_\text{PI}}} % |
\renewcommand{\Nus}{\ensuremath{\text{N}_\text{PE}}} % |
\head{Computing coverage and event relevance} SBLD requires an assumption about what makes an event \emph{relevant} |
and a method for computing this relevance. Our method takes inspiration |
from Spectrum-Based Fault Localization (SBFL) in which the suspiciousness |
or fault-proneness of a program statement is treated as a function of |
the number of times the statement was activated in a failing test case, |
combined with the number of times it is skipped in a passing test case~\cite{Jones2002,Abreu2007,Abreu2009}. |
The four primitives that need to be computed are shown on the right-hand side in Table~\ref{table:measures}. |
We treat each abstracted event as a statement and study their occurrences |
in the logs like Fault Localization tracks the activation of statements in test cases. |
We compute the analysis primitives by devising a binary |
\emph{coverage matrix} whose columns represent every unique event |
observed in the set of failing and successful logs while each row $r$ |
represents a log and tracks whether the event at column $c$ occurred in |
log $r$ (1), or not (0), as shown in Figure~\ref{fig:approach}. |
By computing these primitives, we can rank each event by using an |
\emph{interestingness measure} (also referred to as ranking |
metric, heuristic, or similarity coefficient~\cite{Wong2016}). |
The choice of interestingness measure |
is ultimately left to the user, as these are context dependent and |
there is no generally optimal choice of interestingness measure~\cite{Yoo2014}. |
In this paper we consider a |
selection of nine interestingness measures prominent in the literature |
and a simple metric that emphasizes the events that exclusively occur |
in failing logs in the spirit of the \emph{union model} discussed |
by Renieres et al.~\cite{renieres2003:fault}. We |
report on the median performance of these interestingness measures with the intention of providing a |
representative, yet unbiased, result. The ten measures considered are |
precisely defined in Table~\ref{table:measures}. |
\begin{table*} |
\centering |
\begin{tabular}{c@{\hspace{10mm}}c} |
{\renewcommand{\arraystretch}{1.7} % |
\begin{tabular}{lc} |
\toprule |
measure & formula \\\midrule |
Tarantula \cite{Jones2001,Jones2002} & % |
\( \frac{ \frac{ \cef{} }{ \cef{} + \cnf{} } }{ \frac{ \cef{} }{ \cef{} + \cnf{} } + \frac{ \cep{} }{ \cep{} + \cnp{} } } \) |
\\ |
Jaccard \cite{Jaccard1912,Chen2002} & % |
\( \frac{ \Ncf }{ \Ncf + \Nuf + \Ncs } \) |
\\ |
Ochiai \cite{Ochiai1957,Abreu2006} & % |
\( \frac{ \Ncf }{ \sqrt{ ( \cef + \cnf ) \times ( \cef + \cep ) } } \) |
\\ |
Ochiai2 \cite{Ochiai1957, Naish2011} & % |
\( \frac{ \Aef \times \Anp }{ \sqrt{ ( \Aef + \Aep ) \times ( \Anf + \Anp ) \times ( \Aef + \Anf) \times ( \Aep + \Anp ) } } \) |
\\ |
Zoltar \cite{Gonzalez2007} & % |
\( \frac{ \Ncf }{ \Ncf + \Nuf + \Ncs + \frac { 10000 \times \Nuf \times \Ncs }{ \Ncf } } \) |
\\ |
D$^\star$ \cite{Wong2014} (we use $\star = 2$) & % |
\( \frac{ (\cef)^\star }{ \cnf + \cep } \) |
\\ |
O$^p$ \cite{Naish2011} & % |
\( \Aef - \frac{ \Aep }{ \Aep + \Anp + 1} \) |
\\ |
Wong3 \cite{Wong2007,Wong2010} & |
\( \Aef - h, \text{where~} h = \left\{ |
\scalebox{.8}{\(\renewcommand{\arraystretch}{1} % |