title: Is there a log file analyzer for log4j files?
body: <p>I am looking for some kind of analyzer tool for log files generated by log4j files. I am looking something more advanced than <em>grep</em>? What are you using for log file analysis?</p>
  
  <p>I am looking for following kinds of features:</p>
  
  <ul>
  <li>The tool should tell me how many time a given log statement or a stack trace has occurred, preferably with support for some kinds of patterns (eg. number of log statements matching 'User [a-z]* logged in'). </li>
  <li>Breakdowns by log level (how many INFO, DEBUG lines) and by class that initiated the log message would be nice.</li>
  <li>Breakdown by date (how many log statements in given time period)</li>
  <li>What log lines occur commonly together?</li>
  <li>Support for several files since I am using log rolling</li>
  <li>Hot spot analysis: find if there is a some time period when there is unusually high number of log statements</li>
  <li>Either command-line or GUI are fine</li>
  <li>Open Source is preferred but I am also interested in commercial offerings</li>
  </ul>
  
  <p>My log4j configuration uses org.apache.log4j.PatternLayout with pattern <code>%d %p %c - %m%n</code> but that could be adapted for analyzer tool.</p>