Hello,
I'm seeing a difference in the way Tomcat handles logging exceptions thrown by
a servlet, and I wonder if it's a configuration change or if this is simply how
Tomcat is expected to behave.
Tomcat versions tested: 5.5.26, 6.0.35, 7.0.25
OS: Windows 7
Java: 1.5.0_22 for Tomcat 5.5.26 and 6.0.35, 1.6.0_24 for Tomcat 7.0.25
To test, I created a webapp with a single servlet, ExceptionServlet, that
simply throw a ServletException in its service() method, e.g.:
public class ExceptionServlet extends HttpServlet {
protected void service(HttpServletRequest arg0, HttpServletResponse
arg1)
throws ServletException, IOException {
throw new ServletException("HEY SERVLET EXCEPTION");
}
}
Further, the webapp uses log4j (1.2.16) and commons-logging (1.1.1). The
log4j.properties for the webapp looks like this:
log4j.rootLogger=INFO,A
log4j.appender.A=org.apache.log4j.RollingFileAppender
log4j.appender.A.file=/opt/personal/logs/ex/ex.info.log
log4j.appender.A.layout=org.apache.log4j.PatternLayout
log4j.appender.A.layout.conversionPattern=%m%n
log4j.appender.A.maxFileSize=10MB
log4j.appender.A.maxBackupIndex=10
In a default deployment of Tomcat 5.5.26, I drop the webapp in the webapps
directory, start up Tomcat, and call the ExceptionServlet. The resultant
exception message and stack trace appear in the log file specified by the
webapp's log4j.properties file, as I would expect.
Servlet.service() for servlet ex threw exception
javax.servlet.ServletException: HEY SERVLET EXCEPTION
at personal.ExceptionServlet.service(ExceptionServlet.java:17)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:269)
...
However, in a default deployment of Tomcat 6.0.35 or Tomcat 7.0.25, when I drop
the webapp in the webapps directory, start up the respective Tomcat, and invoke
the ExceptionServlet, the resultant exception message and stack trace appear in
the Tomcat's log file, e.g. $TOMCAT_HOME/logs/localhost.2012-02-09.log. It's
pretty much the same log message as above:
# from Tomcat 7.0.25
SEVERE: Servlet.service() for servlet [ex] in context with path [/et] threw
exception [HEY SERVLET EXCEPTION] with root cause
javax.servlet.ServletException: HEY SERVLET EXCEPTION
at personal.ExceptionServlet.service(ExceptionServlet.java:17)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
...
I made no configuration changes to any of the Tomcat installations.
So I guess my questions are:
1. Is it correct to expect that exceptions thrown by a servlet should be logged
in the webapp's log files?
2. If so, what changed between Tomcat 5.5 and Tomcat 6.0/7.0 that would cause
exceptions thrown by a servlet to be logged in Tomcat's log files, or what
configuration change do I need to make so that the exception appears in the
webapp's logs?
Thanks in advance for any insights into my problem!
Chris
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