title: log4j not printing the stacktrace for exceptions
body: <p>I am using log4j with tomcat. When I log exceptions in my JSPs, servlets:</p>
  
  <pre><code>private Logger _log = Logger.getLogger(this.getClass());
  ...
  try{...} catch (Exception e) {
      _log.error("Error refreshing all prices", e);
  }
  </code></pre>
  
  <p>I only get the first line of the exception, without a stacktrace. </p>
  
  <blockquote>
    <p>17-Feb 17:37:45 ERROR AutoContrib:175 - Exception while publishing csv file:
    java.lang.ArrayIndexOutOfBoundsException</p>
  </blockquote>
  
  <p>Not very helpful at all!</p>
  
  <p>My log4j.properties file (/tomcat/common/classes/log4j.properties) looks like this:</p>
  
  <pre><code>log4j.appender.stdout=org.apache.log4j.ConsoleAppender
  log4j.appender.stdout.Target=System.out
  log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
  log4j.appender.stdout.layout.ConversionPattern=%d{dd-MMM HH:mm:ss} %5p %c{1}:%L - %m%n
  log4j.appender.stdout.threshold=info
  
  log4j.appender.file=org.apache.log4j.RollingFileAppender
  log4j.appender.file.maxFileSize=5000KB
  log4j.appender.file.maxBackupIndex=10
  log4j.appender.file.File=${catalina.home}/logs/web.log
  log4j.appender.file.layout=org.apache.log4j.PatternLayout
  log4j.appender.file.layout.ConversionPattern=%d{dd-MMM HH:mm:ss} %5p %c{1}:%L - %m%n
  log4j.appender.file.threshold=info
  
  log4j.rootLogger=debug, stdout, file
  </code></pre>