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From Brian Cook <>
Subject Tomcat5.5 stops responding after sevral days
Date Fri, 16 Sep 2005 22:49:20 GMT

I am running Tomcat 5.5 and about every 2 - 5 days it stops fully 
responding.  Meaning that nothing will load in a browser when accessing 
Tomcat but the browser will never time out either.  It will just sit 
there waiting forever.  It happens to all of the modules loaded in 
webapps as well as to the admin and deployment modules.  Nothing in 
Tomcat will respond.  Stopping and then restarting Tomcat resolves the 
problem for 2 -5 days until it happens again.

Catalina.out does not show any errors, exceptions, or warnings before it 
happens.  Netstat only shows 5 - 10 connections well under the max set 
for any of the modules.  Top shows the processor 0% userd with 50 - 100 
MB of RAM and lots of swap space available.  The database logs also do 
not report any errors.

Usually when I see the symptom of Tomcat not responding but not timing 
out either.  It is caused by an in accessible data base.  But in those 
instances the connection failure is logged in catalina.out, it only 
effects the one module that can not get to its data base.  This lead me 
to wonder if Tomcat was some how losing its connection to the data base 
that stores the realm user data.(NOTE:  This instance of Tomcat is 
configured to access MySQL to get user realm info)  But if that were the 
case I would have assumed the failed connection would be logged in 
Catalina.out.  Just in case I added "?autoReconnect=true" to all of the 
DB URLs but it has not helped.

I could use some ideas of other things I should be looking into and or 
options I should be setting to log more details.  Thoughts any one?

I have included system details and the server.xml file below

OS :  Redhat 9.0
JVM :  1.5.3
Tomcat : 5.5
MySQL : 4.1.8

<!-- Example Server Configuration File -->
<!-- Note that component elements are nested corresponding to their
     parent-child relationships with each other -->

<!-- A "Server" is a singleton element that represents the entire JVM,
     which may contain one or more "Service" instances.  The Server
     listens for a shutdown command on the indicated port.

     Note:  A "Server" is not itself a "Container", so you may not
     define subcomponents such as "Valves" or "Loggers" at this level.

<Server port="8005" shutdown="SHUTDOWN">

  <!-- Comment these entries out to disable JMX MBeans support used for the
       administration web application -->
className="org.apache.catalina.mbeans.ServerLifecycleListener" />
className="org.apache.catalina.mbeans.GlobalResourcesLifecycleListener" />

  <!-- Global JNDI resources -->

    <!-- Test entry for demonstration purposes -->
    <Environment name="simpleValue" type="java.lang.Integer" value="30"/>

    <!-- Editable user database that can also be used by
         UserDatabaseRealm to authenticate users -->
    <!-- <Resource name="UserDatabase"
                description="User database that can be updated and saved"
                pathname="conf/tomcat-users.xml" /> -->

   <!--  <Resource name="UserDatabase"
                description="User database that can be updated and saved"
                maxActive="6" maxIdle="2" />

  <!-- A "Service" is a collection of one or more "Connectors" that share
       a single "Container" (and therefore the web applications visible
       within that Container).  Normally, that Container is an "Engine",
       but this is not required.

       Note:  A "Service" is not itself a "Container", so you may not
       define subcomponents such as "Valves" or "Loggers" at this level.

  <!-- Define the Tomcat Stand-Alone Service -->
  <Service name="Catalina">

    <!-- A "Connector" represents an endpoint by which requests are received
         and responses are returned.  Each Connector passes requests on 
to the
         associated "Container" (normally an Engine) for processing.

         By default, a non-SSL HTTP/1.1 Connector is established on port 
         You can also enable an SSL HTTP/1.1 Connector on port 8443 by
         following the instructions below and uncommenting the second 
         entry.  SSL support requires the following steps (see the SSL 
         HOWTO in the Tomcat 5 documentation bundle for more detailed
         * If your JDK version 1.3 or prior, download and install JSSE 
1.0.2 or
           later, and put the JAR files into "$JAVA_HOME/jre/lib/ext".
         * Execute:
             %JAVA_HOME%\bin\keytool -genkey -alias tomcat -keyalg RSA 
             $JAVA_HOME/bin/keytool -genkey -alias tomcat -keyalg RSA  
           with a password value of "changeit" for both the certificate and
           the keystore itself.

         By default, DNS lookups are enabled when a web application calls
         request.getRemoteHost().  This can have an adverse impact on
         performance, so you can disable it by setting the
         "enableLookups" attribute to "false".  When DNS lookups are 
         request.getRemoteHost() will return the String version of the
         IP address of the remote client.

    <!-- Define a non-SSL HTTP/1.1 Connector on port 8080 -->
    <Connector port="80"
                disableUploadTimeout="true" />
    <!-- Note : To disable connection timeouts, set connectionTimeout value
     to 0 -->

        <!-- Note : To use gzip compression you could set the following 
properties :

                           noCompressionUserAgents="gozilla, traviata"

    <!-- Define a SSL HTTP/1.1 Connector on port 8443 -->
    <Connector port="8443" maxHttpHeaderSize="8192"
               maxThreads="150" minSpareThreads="25" maxSpareThreads="75"
               enableLookups="false" disableUploadTimeout="true"
               acceptCount="100" scheme="https" secure="true"
               clientAuth="false" sslProtocol="TLS" />

    <!-- Define an AJP 1.3 Connector on port 8009 -->
    <Connector port="8009"
               protocol="AJP/1.3" />

    <!-- Define a Proxied HTTP/1.1 Connector on port 8082 -->
    <!-- See proxy documentation for more information about using this. -->
    <Connector port="8082"
               maxThreads="150" minSpareThreads="25" maxSpareThreads="75"
               enableLookups="false" acceptCount="100" 
               proxyPort="80" disableUploadTimeout="true" />

    <!-- An Engine represents the entry point (within Catalina) that 
         every request.  The Engine implementation for Tomcat stand alone
         analyzes the HTTP headers included with the request, and passes 
         on to the appropriate Host (virtual host). -->

    <!-- You should set jvmRoute to support load-balancing via AJP ie :
    <Engine name="Standalone" defaultHost="localhost" 
    <!-- Define the top level container in our container hierarchy -->
    <Engine name="Catalina" defaultHost="localhost">

      <!-- The request dumper valve dumps useful debugging information about
           the request headers and cookies that were received, and the 
           headers and cookies that were sent, for all requests received by
           this instance of Tomcat.  If you care only about requests to a
           particular virtual host, or a particular application, nest this
           element inside the corresponding <Host> or <Context> entry 

           For a similar mechanism that is portable to all Servlet 2.4
           containers, check out the "RequestDumperFilter" Filter in the
           example application (the source for this filter may be found in

           Request dumping is disabled by default.  Uncomment the following
           element to enable it. -->
      <Valve className="org.apache.catalina.valves.RequestDumperValve"/>

      <!-- Because this Realm is here, an instance will be shared 
globally -->

      <!-- This Realm uses the UserDatabase configured in the global JNDI
           resources under the key "UserDatabase".  Any edits
           that are performed against this UserDatabase are immediately
           available for use by the Realm.  -->
      <Realm className="org.apache.catalina.realm.UserDatabaseRealm"

      <!-- Comment out the old realm but leave here for now in case we
           need to go back quickly -->
      <Realm className="org.apache.catalina.realm.MemoryRealm" />

      <!-- Replace the above Realm with one of the following to get a Realm
           stored in a database and accessed via JDBC -->


      <Realm  className="org.apache.catalina.realm.JDBCRealm"
                roleNameCol="role" />

      <Realm  className="org.apache.catalina.realm.JDBCRealm"
         connectionName="scott" connectionPassword="tiger"
              userTable="users" userNameCol="user_name" 
          userRoleTable="user_roles" roleNameCol="role_name" />

      <Realm  className="org.apache.catalina.realm.JDBCRealm"
              userTable="users" userNameCol="user_name" 
          userRoleTable="user_roles" roleNameCol="role_name" />

      <!-- Define the default virtual host
           Note: XML Schema validation will not work with Xerces 2.2.
      <Host name="localhost"

        <!-- Defines a cluster for this node,
             By defining this element, means that every manager will be 
             So when running a cluster, only make sure that you have 
webapps in there
             that need to be clustered and remove the other ones.
             A cluster has the following parameters:

             className = the fully qualified name of the cluster class

             name = a descriptive name for your cluster, can be anything

             mcastAddr = the multicast address, has to be the same for 
all the nodes

             mcastPort = the multicast port, has to be the same for all 
the nodes
             mcastBindAddr = bind the multicast socket to a specific address
             mcastTTL = the multicast TTL if you want to limit your 
             mcastSoTimeout = the multicast readtimeout

             mcastFrequency = the number of milliseconds in between 
sending a "I'm alive" heartbeat

             mcastDropTime = the number a milliseconds before a node is 
considered "dead" if no heartbeat is received

             tcpThreadCount = the number of threads to handle incoming 
replication requests, optimal would be the same amount of threads as n

             tcpListenAddress = the listen address (bind address) for 
TCP cluster request on this host,
                                in case of multiple ethernet cards.
                                auto means that address becomes

             tcpListenPort = the tcp listen port

             tcpSelectorTimeout = the timeout (ms) for the method in case the OS
                                  has a wakup bug in java.nio. Set to 0 
for no timeout

             printToScreen = true means that managers will also print to 

             expireSessionsOnShutdown = true means that

             useDirtyFlag = true means that we only replicate a session 
after setAttribute,removeAttribute has been called.
                            false means to replicate the session after 
each request.
                            false means that replication would work for 
the following piece of code: (only for SimpleTcpReplicationManager)
                            HashMap map = 
             replicationMode = can be either 'pooled', 'synchronous' or 
                               * Pooled means that the replication 
happens using several sockets in a synchronous way. Ie, the data gets repl
icated, then the request return. This is the same as the 'synchronous' 
setting except it uses a pool of sockets, hence it is multithreaded. T
his is the fastest and safest configuration. To use this, also increase 
the nr of tcp threads that you have dealing with replication.
                               * Synchronous means that the thread that 
executes the request, is also the
                               thread the replicates the data to the 
other nodes, and will not return until all
                               nodes have received the information.
                               * Asynchronous means that there is a 
specific 'sender' thread for each cluster node,
                               so the request thread will queue the 
replication request into a "smart" queue,
                               and then return to the client.
                               The "smart" queue is a queue where when a 
session is added to the queue, and the same session
                               already exists in the queue from a 
previous request, that session will be replaced
                               in the queue instead of replicating two 
requests. This almost never happens, unless there is a
                               large network delay.
            When configuring for clustering, you also add in a valve to 
catch all the requests
            coming in, at the end of the request, the session may or may 
not be replicated.
            A session is replicated if and only if all the conditions 
are met:
            1. useDirtyFlag is true or setAttribute or removeAttribute 
has been called AND
            2. a session exists (has been created)
            3. the request is not trapped by the "filter" attribute

            The filter attribute is to filter out requests that could 
not modify the session,
            hence we don't replicate the session after the end of this 
            The filter is negative, ie, anything you put in the filter, 
you mean to filter out,
            ie, no replication will be done on requests that match one 
of the filters.
            The filter attribute is delimited by ;, so you can't escape 
out ; even if you wanted to.

            filter=".*\.gif;.*\.js;" means that we will not replicate 
the session after requests with the URI
            ending with .gif and .js are intercepted.
            The deployer element can be used to deploy apps cluster wide.
            Currently the deployment only deploys/undeploys to working 
members in the cluster
            so no WARs are copied upons startup of a broken node.
            The deployer watches a directory (watchDir) for WAR files 
when watchEnabled="true"
            When a new war file is added the war gets deployed to the 
local instance,
            and then deployed to the other instances in the cluster.
            When a war file is deleted from the watchDir the war is 
undeployed locally
            and cluster wide





        <!-- Normally, users must authenticate themselves to each web app
             individually.  Uncomment the following entry if you would like
             a user to be authenticated the first time they encounter a
             resource protected by a security constraint, and then have that
             user identity maintained across *all* web applications 
             in this virtual host. -->
        <Valve className="org.apache.catalina.authenticator.SingleSignOn" />

        <!-- Access log processes all requests for this virtual host.  By
             default, log files are created in the "logs" directory 
relative to
             $CATALINA_HOME.  If you wish, you can specify a different
             directory with the "directory" attribute.  Specify either a 
             (to $CATALINA_HOME) or absolute path to the desired directory.
        <Valve className="org.apache.catalina.valves.AccessLogValve"
                 directory="logs"  prefix="localhost_access_log." 
                 pattern="common" resolveHosts="false"/>

        <!-- Access log processes all requests for this virtual host.  By
             default, log files are created in the "logs" directory 
relative to
             $CATALINA_HOME.  If you wish, you can specify a different
             directory with the "directory" attribute.  Specify either a 
             (to $CATALINA_HOME) or absolute path to the desired directory.
             This access log implementation is optimized for maximum 
             but is hardcoded to support only the "common" and 
"combined" patterns.
                 directory="logs"  prefix="localhost_access_log." 
                 pattern="common" resolveHosts="false"/>
        <!-- Access log processes all requests for this virtual host.  By
             default, log files are created in the "logs" directory 
relative to
             $CATALINA_HOME.  If you wish, you can specify a different
             directory with the "directory" attribute.  Specify either a 
             (to $CATALINA_HOME) or absolute path to the desired directory.
             This access log implementation is optimized for maximum 
             but is hardcoded to support only the "common" and 
"combined" patterns.

             This valve use NIO direct Byte Buffer to asynchornously 
store the
                 directory="logs"  prefix="localhost_access_log." 
                 pattern="common" resolveHosts="false"/>






Brian Cook
Digital Services Analyst
Print Time Inc.

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