[jetty-users] Servlet Filter is Called Twice in Embedded Jetty

["Igal @ Lucee.org" <igal@xxxxxxxxx>]

I have written a very simple test Filter, and am running it in an embedded Jetty 9.2.18.v20160721 in debug mode in IntelliJ IDEA:

        System.out.println(TestFilter.class.getSimpleName()       // line 12
                + " > "
                + ((HttpServletRequest)servletRequest).getRequestURL()
                + ": IP "+ servletRequest.getRemoteAddr()
                + "; at "
                + new Date().toString());

        // Pass request back down the filter chain
        filterChain.doFilter(servletRequest, servletResponse);    // line 20
    }

and added it to web.xml:

<filter>
    <filter-name>TestFilter</filter-name>
    <filter-class>net.twentyonesolutions.TestFilter</filter-class>
</filter>

<filter-mapping>
    <filter-name>TestFilter</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>

When running in debug mode in IntelliJ IDEA, the Filter's doFilter() method is called twice, and the output from line 12 is written twice.  You can see the stack trace at the 2nd call below.

When I deploy the Filter to regular Jetty (same version), or Tomcat, the output from line 12 is only written once, as expected.

Why is this happening in debug/embedded mode?  TIA

I posted this question with a bit more detail at http://stackoverflow.com/questions/39337962/why-does-my-servlet-filter-run-twice

Stack trace at 2nd call:

[net.twentyonesolutions.TestFilter.doFilter(TestFilter.java:20)
    ,org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1652)
    ,net.twentyonesolutions.TestFilter.doFilter(TestFilter.java:20)
    ,org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1652)
    ,org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:585)
    ,org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143)
    ,org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:577)
    ,org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:223)
    ,org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1127)
    ,org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:515)
    ,org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:185)
    ,org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1061)
    ,org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141)
    ,org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:97)
    ,org.eclipse.jetty.server.Server.handle(Server.java:497)
    ,org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:310)
    ,org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:245)
    ,org.eclipse.jetty.io.AbstractConnection$2.run(AbstractConnection.java:540)
    ,org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:635)
    ,org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:555)
    ,java.lang.Thread.run(Thread.java:745)]

--

Igal Sapir
Lucee Core Developer
Lucee.org