diff options
Diffstat (limited to 'rubbos/app/tomcat-connectors-1.2.32-src/xdocs/reference/workers.xml')
| -rw-r--r-- | rubbos/app/tomcat-connectors-1.2.32-src/xdocs/reference/workers.xml | 1155 |
1 files changed, 1155 insertions, 0 deletions
diff --git a/rubbos/app/tomcat-connectors-1.2.32-src/xdocs/reference/workers.xml b/rubbos/app/tomcat-connectors-1.2.32-src/xdocs/reference/workers.xml new file mode 100644 index 00000000..543112cf --- /dev/null +++ b/rubbos/app/tomcat-connectors-1.2.32-src/xdocs/reference/workers.xml @@ -0,0 +1,1155 @@ +<?xml version="1.0"?> +<!-- + Licensed to the Apache Software Foundation (ASF) under one or more + contributor license agreements. See the NOTICE file distributed with + this work for additional information regarding copyright ownership. + The ASF licenses this file to You under the Apache License, Version 2.0 + (the "License"); you may not use this file except in compliance with + the License. You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. +--> +<!DOCTYPE document [ + <!ENTITY project SYSTEM "project.xml"> +]> +<document url="workers.html"> + + &project; + + <properties> + <author email="mturk@apache.org">Mladen Turk</author> + <title>workers.properties configuration</title> + </properties> + +<body> + +<section name="Introduction"> +<br/> +<p> +A <b>Tomcat worker</b> is a Tomcat instance that is waiting to execute servlets or any other content +on behalf of some web server. For example, we can have a web server such as +Apache forwarding servlet requests to a Tomcat process (the worker) running behind it. +</p> +<p> +The scenario described above is a very simple one; +in fact one can configure multiple Tomcat workers to serve servlets on +behalf of a certain web server. +The reasons for such configuration can be: +</p> +<ul> +<li> +We want different contexts to be served by different Tomcat workers to provide a +development environment where all the developers share the same web server but +own a Tomcat worker of their own. +</li> +<li> +We want different virtual hosts served by different Tomcat processes to provide a +clear separation between sites belonging to different companies. +</li> +<li> +We want to provide load balancing, meaning run multiple Tomcat workers each on a +machine of its own and distribute the requests between them. +</li> +</ul> + +<p> +There are probably more reasons for having multiple workers but I guess that this list is enough... +</p> +<p> +Tomcat workers are defined in a properties file dubbed <b>workers.properties</b> and this tutorial +explains how to work with it. +</p> +</section> + +<section name="Configuration File Basics"> +<br/> +<p>Defining workers to the Tomcat web server plugin can be done using a properties file +(a sample file named workers.properties is available in the conf/ directory). +</p> + +<subsection name="Format, Comments, Whitespace"> +<br/> +<p> +The lines in the file define properties. The general format is +</p> +<p><strong><name>=<value></strong></p> +<p> +</p> +Dots are used as part of the name to represent a configuration hierarchy. +<p> +Invalid directives will be logged during web server startup and prevent the web server +from working properly. Some directives have been deprecated. Although they will +still work, you should replace them by their +<a href="#Deprecated Worker Directives">successors</a>. +</p> +<p> +Some directives are allowed multiple times. This will be explicitly +noted in the tables below. +</p> +<p> +Whitespace at the beginning and the end of a property name or value gets ignored. +Comments can be placed in any line and start with a hash sign '#'. +Any line contents behind the hash sign get ignored. +</p> +</subsection> + +<subsection name="Global Properties"> +<br/> +<p> +These directives have global scope. +</p> +<directives> +<directive name="worker.list" default="ajp13" required="true"> +A comma separated list of workers names that the JK will use. When starting up, +the web server plugin will instantiate the workers whose name appears in the +worker.list property, these are also the workers to whom you can map requests. +<p> +This directive can be used multiple times. +</p> +</directive> +<directive name="worker.maintain" default="60" required="false"> +Worker connection pool maintain interval in seconds. If set to the positive +value JK will scan all connections for all workers specified in worker.list +directive and check if connections needs to be recycled. +<p> +Furthermore any load balancer does a global maintenance every worker.maintain +seconds. During global maintenance load counters are decayed and workers +in error are checked for recover_time. +</p> +<p> +This feature has been added in <b>jk 1.2.13</b>. +</p> +</directive> +</directives> +</subsection> + +<subsection name="Worker Properties"> +<br/> +<p> +Each worker configuration directive consists of three words separated by a dot: +</p> +<p><strong>worker.<worker name>.<directive>=<value></strong></p> +<p> +The first word is always <b>worker</b>. +The second word is the worker name you can choose. In the case of load-balancing, +the worker name has an additional meaning. Please consult the +<a href="../generic_howto/loadbalancers.html">Load Balancer HowTo</a>. +</p> +<warn> +The name of the worker can contain only the alphanumeric characters +<b>[a-z][A-Z][0-9][_\-]</b> and is case sensitive. +</warn> +</subsection> + +<subsection name="Variables, Environment Variables"> +<br/> +<p> +You can define and use variables in the workers.properties file. +To define a variable you use the syntax: +</p> +<p><strong><variable_name>=<value></strong></p> +<p> +Dots are allowed in the variable name, but you have to be careful +not to use variable names, that clash with standard directives. +Therefore variable names should never start with "worker.". +</p> +<p> +To use a variable, you can insert "$(variable_name)" at any place +on the value side of a property line. If a variable has not been +defined before its use, we will search the process environment for +a variable with the same name and use their value. +</p> +</subsection> + +<subsection name="Property Inheritance"> +<br/> +<p>Often one wants to use the same property values for various workers. +To reduce duplication of configuration lines and to ease the maintenance of +the file, you can inherit properties from one worker to another, or even +from a template to real workers. +</p> +<p> +The directive "reference" allows to copy configurations between workers +in a hierarchical way. If worker castor sets <b>worker.castor.reference=worker.pollux</b> +then it inherits all properties of <b>pollux</b>, except for the ones that +are explicitly set for <b>castor</b>. +</p> +<p> +Please note, that the value of the directive is not only the name of the referred worker, +but the complete prefix including "worker.". +</p> +<p> +To use a template worker simply define it like a real worker, but do not add it +to the "worker.list" or as a member to any load balancer. Such a template worker +does not have to contain mandatory directives. This approach is especially useful, +if one has a lot of balanced workers in a load balancer +and these workers share most of their properties. You can set all of these properties +in a template worker, e.g. using the prefix "worker.template1", and then simply +reference those common properties in all balanced workers. +</p> +<p> +References can be used to inherit properties over multiple hops in a hierarchical way. +</p> +<p> +This feature has been added in <b>jk 1.2.19</b>. +</p> +</subsection> +</section> + +<section name="List of All Worker Directives"> +<br/> +<subsection name="Mandatory Directives"> +<br/> +<p>Mandatory directives are the one that each worker <b>must</b> contain. Without them the worker will +be unavailable or will misbehave. Those directives will be marked with a <strong>strong</strong> font in the following tables. +</p> +<directives> +<directive name="type" default="ajp13" required="true"> +Type of the worker (can be one of ajp13, ajp14, jni, lb or status). The type of the worker +defines the directives that can be applied to the worker. +<p>AJP13 worker is the preferred worker type that JK uses for communication +between web server and Tomcat. This type of worker uses sockets as communication +channel. For detailed description of the AJP13 protocol stack browse to +<a href="../ajp/ajpv13a.html">AJPv13 protocol specification</a> +</p> +<warn>JNI workers have been deprecated. They will likely not work. Do not use them.</warn> +</directive> +</directives> +</subsection> + +<subsection name="Connection Directives"> +<br/> +<p>Connection directives defines the parameters needed to connect and maintain +the connections pool of persistent connections between JK and remote Tomcat. +</p> +<directives> + +<directive name="host" default="localhost" required="false"> +Host name or IP address of the backend Tomcat instance. The remote Tomcat must +support the ajp13 protocol stack. The host name can have a <b>port</b> number +embedded separated by the colon (':') character. +</directive> + +<directive name="port" default="8009" required="false"> +Port number of the remote Tomcat instance listening for defined protocol requests. +The default value depends on the worker type. For AJP13 workers the default port is +<b>8009</b>, while for AJP14 type of worker that value is <b>8011</b>. +</directive> + +<directive name="socket_timeout" default="0" required="false"> +Socket timeout in seconds used for the communication channel between JK and remote host. +If the remote host does not respond inside the timeout specified, JK will generate an error, +and retry again. If set to zero (default) JK will wait for an infinite amount of time +on all socket operations. +</directive> + +<directive name="socket_connect_timeout" default="socket_timeout*1000" required="false"> +Socket connect timeout in milliseconds used for the communication channel between JK and remote host. +If the remote host does not respond inside the timeout specified, JK will generate an error, +and retry again. +<p> +Note that <code>socket_timeout</code> is in seconds, and +<code>socket_connect_timeout</code> in milliseconds, +so in absolute terms the default <code>socket_connect_timeout</code> is +equal to <code>"socket_timeout</code>. +</p> +<p> +This feature has been added in <b>jk 1.2.27</b>. +</p> +</directive> + +<directive name="socket_keepalive" default="False" required="false"> +This directive should be used when you have a firewall between your webserver +and the Tomcat engine, who tend to drop inactive connections. This flag will tell the Operating System +to send <code>KEEP_ALIVE</code> messages on inactive connections (interval depend on global OS settings, +generally 120 minutes), and thus prevent the firewall to cut inactive connections. +To enable keepalive set this property value to <b>True</b>. +<p> +The problem with Firewall cutting inactive connections is that sometimes, neither webserver or Tomcat +have information about the cut and couldn't handle it. +</p> +</directive> + +<directive name="ping_mode" default="" required="false"> +This flag determines, under which conditions established +connections are probed to ensure they are still working. +The probe is done with an empty AJP13 packet (CPing) and +expects to receive an appropriate answer (CPong) within +some timeout. +<p> +The value of the flag can be any combination of the following +flags (multiple values are combined without any separators): +</p> +<p><b>C</b> (connect): If set, the connection will +be probed once after connecting to the backend. The timeout +can be set by <code>connect_timeout</code>. If it is not set, +the value of <code>ping_timeout</code> will be used instead. +</p> +<p><b>P</b> (prepost): If set, the connection will +be probed before sending each request to the backend. The timeout +can be set by <code>prepost_timeout</code>. If it is not set, +the value of <code>ping_timeout</code> will be used instead. +</p> +<p><b>I</b> (interval): If set, the connection will +be probed during the regular internal maintenance cycle, +but only if it is idle longer than +<code>connection_ping_interval</code>. The timeout +can be set by <code>ping_timeout</code>. +</p> +<p><b>A</b> If set, all of the above probes will be used. +</p> +<p> +This feature has been added in <b>jk 1.2.27</b>. Connect and +prepost probing were already available via <code>connect_timeout</code> +and <code>prepost_timeout</code> since version <b>jk 1.2.6</b>. +</p> +</directive> + +<directive name="ping_timeout" default="10000" required="false"> +Timeout in milliseconds used when waiting for the CPong answer of a +CPing connection probe. The activation of the probes is done via +<code>ping_mode</code>. The timeouts for <code>ping_mode</code> +connect and prepost can be overwritten individually via +<code>connect_timeout</code> and <code>prepost_timeout</code>. +<p> +For compatibility reasons, CPing/CPong is also used, whenever +<code>connect_timeout</code> or <code>prepost_timeout</code> are set, +even if <code>ping_mode</code> is empty. +</p> +<p> +This feature has been added in <b>jk 1.2.27</b>. +</p> +</directive> + +The usage depend on the <code>ping_mode</code> flags used. +directive <code>connection_ping_interval</code> was not set, the +value of <code>(ping_timeout/1000) * 10</code> will be used as +<code>connection_ping_interval</code> value. + +<directive name="connection_ping_interval" default="0 / (ping_timeout/1000)*10" required="false"> +When using interval connection probing, connections idle for longer than this +interval in seconds are probed by CPing packets whether they still work. +<p>Interval probing can be activated either by <code>ping_mode</code>, +or by setting <code>connection_ping_interval</code> to some value bigger +than zero. If you activate interval probing via <code>ping_mode</code>, +then the default value of <code>connection_ping_interval</code> is +<code>(ping_timeout/1000) * 10</code>. Note that <code>ping_timeout</code> +is in milliseconds, and <code>connection_ping_interval</code> in seconds, +so in absolute terms the default <code>connection_ping_interval</code> is +10 times <code>ping_timeout</code>. +</p> +<p> +This feature has been added in <b>jk 1.2.27</b>. +</p> +</directive> + +<directive name="connection_pool_size" default="see text" required="false"> +This defines the number of connections made to the AJP backend that +are maintained as a connection pool. +It will limit the number of those connection that each web server child +process can made. +<p> +Connection pool size property is only used for multi threaded +web servers such as Apache, IIS and Netscape/Sun. The connection_pool_size property +needs to reflect the number of requests one web server process should +be able to send to a backend in parallel. Usually this is the same as +the number of threads per web server process. JK will discover +this number for the Apache web server automatically and set the pool size to +this value. For IIS the default value is 250 (before version 1.2.20: 10), +for Netscape/Sun the default value is 1. +</p> +<p>We strongly recommend adjusting this value for IIS and the Netscape/Sun +to the number of requests one web server process should +be able to send to a backend in parallel. You should measure how many connections +you need during peak activity without performance problems, and then add some +percentage depending on your growth rate. Finally you should check, +whether your web server processes are able to use at least as many threads, +as you configured as the pool size. +</p> +<warn>Do not use connection_pool_size with values higher then 1 on <b>Apache 2.x prefork</b> or <b>Apache 1.3.x</b>!</warn> +</directive> + +<directive name="connection_pool_minsize" default="(pool+1)/2" required="false"> +Minimum size of the connection pool that will be maintained. +<p> +Its default value is (connection_pool_size+1)/2. +</p> +<warn>Do not use connection_pool_size with values higher then 1 on <b>Apache 2.x prefork</b> or <b>Apache 1.3.x</b>!</warn> +<p> +This feature has been added in <b>jk 1.2.16</b>. +</p> +</directive> + +<directive name="connection_pool_timeout" default="0" required="false"> +Cache timeout property should be used with <b>connection_pool_minsize</b> to specify how many seconds JK should keep +an inactive socket in cache before closing it. This property should be used to reduce the number of threads +on the Tomcat web server. The default value zero disables the closing (infinite timeout). +<p> +Each child could open an ajp13 connection if it has to forward a request to Tomcat, creating +a new ajp13 thread on Tomcat side. +</p> +<p> +The problem is that after an ajp13 connection is created, the child won't drop it +until killed. And since the webserver will keep its childs/threads running +to handle high-load, even it the child/thread handle only static contents, you could +finish having many unused ajp13 threads on the Tomcat side. +</p> +<p> +You should keep this time interval in sync with the <b>connectionTimeout</b> attribute +of your AJP connector in Tomcat's server.xml. Note however, that the value +for mod_jk is given in seconds, the one in server.xml has to use milliseconds. +</p> +</directive> + +<directive name="connection_acquire_timeout" default="retries*retry_interval" required="false"> +Timeout the worker will wait for a free socket in cache before giving up. +<p> +Its default value is <b>retries * retry_interval</b>. +</p> +<p> +This feature has been added in <b>jk 1.2.27</b>. +</p> +</directive> + +<directive name="lbfactor" default="1" required="false"> +Only used for a member worker of a load balancer. +<p> +The integer number lbfactor (load-balancing factor) is +<i>how much we expect this worker to work</i>, or +<i>the worker's work quota</i>. Load balancing factor is compared with other workers +that makes the load balancer. For example if one worker has lb_factor 5 times higher then +other worker, then it will receive five times more requests. +</p> +</directive> + +</directives> + +</subsection> + +<subsection name="Load Balancing Directives"> +<br/> +<p>Load balancer is a virtual worker that does not really communicate with Tomcat workers. +Instead it is responsible for the management of several "real" workers. +The worker is supposed to be a load balancer if it's worker type is <b>lb</b>. +See worker's <b>type</b> directive. +</p> +<p>Loadbalancer directives define the parameters needed to create the workers that are +connecting to a remote cluster of backend Tomcat servers. Each cluster node has to +have a worker defined. +</p> +<p> +Load balancer management includes: +</p> + +<ul> +<li> +Instantiating the workers in the web server. +</li> +<li> +Using the worker's load-balancing factor, perform weighed-round-robin load balancing where +high lbfactor means stronger machine (that is going to handle more requests) +</li> +<li> +Keeping requests belonging to the same session executing on the same Tomcat worker. +</li> +<li> +Identifying failed Tomcat workers, suspending requests to them and instead fall-backing on +other workers managed by the lb worker. +</li> +</ul> + +<p> +The overall result is that workers managed by the same lb worker are load-balanced +(based on their lbfactor and current user session) and also fall-backed so a single +Tomcat process death will not "kill" the entire site. +</p> +<warn> +If you want to use session stickiness, you must set different jvmRoute attributes +in the Engine element in Tomcat's server.xml. Furthermore the names of the workers +which are managed by the balancer have to be equal to the jvmRoute of the Tomcat +instance they connect with. +</warn> +<p> +The restriction on the worker names can be lifted, if you use the route attribute for the workers. +</p> +<p> +The following table specifies properties that the lb worker can accept: +</p> + +<directives> +<directive name="balance_workers" default="" required="true"> +A comma separated list of workers that the load balancer +need to manage. +<p> +This directive can be used multiple times for the same load balancer. +</p> +<p> +This directive replaces old <b>balanced_workers</b> directive and +can be used only with mod_jk versions 1.2.7 and up. +</p> +<warn>As long as these workers should only be used via the load balancer worker, +there is no need to also put them into the <b>worker.list</b> property.</warn> +</directive> + +<directive name="sticky_session" default="True" required="false"> +Specifies whether requests with SESSION ID's should be routed back to the same +Tomcat worker. If sticky_session is set to <b>True</b> or <b>1</b> sessions are sticky, otherwise +sticky_session is set to <b>False</b>. Set sticky_session to <b>False</b> when Tomcat +is using a Session Manager which can persist session data across multiple +instances of Tomcat. +</directive> + +<directive name="sticky_session_force" default="False" required="false"> +Specifies whether requests with SESSION ID's for workers that are in error state +should be rejected. If sticky_session_force is set to <b>True</b> or <b>1</b> +and the worker that matches that SESSION ID is in error state, client will +receive 500 (Server Error). If set to <b>False</b> or <b>0</b> failover on +another worker will be issued with loosing client session. This directive is +used only when you set <b>sticky_session=True</b>. +<p> +This feature has been added in <b>jk 1.2.9</b>. +</p> +</directive> + +<directive name="method" default="Request" required="false"> +Specifies what method load balancer is using for electing the best worker. +Please note, that session stickiness and perfect load balancing are +conflicting targets, especially when the number +of sessions is small, or the usage of sessions is extremely varying +For huge numbers of sessions this usually is not a problem. +<p> +Some methods note, that they aggregate in a sliding time window. They add up +accesses, and on each run of the global maintain method, the load counters +get divided by 2. Usually this happens once a minute, depending on the +setting of worker.maintain. The value of the load counters can be inspected +using the status worker. +</p> +<p> +If method is set to <b>R[equest]</b> the balancer will use number of requests +to find the best worker. Accesses will be distributed according to the +lbfactor in a sliding time window. This is the default value and should be +working well for most applications. +</p> +<p> +If method is set to <b>S[ession]</b> the balancer will use number of sessions +to find the best worker. Accesses will be distributed according to the +lbfactor in a sliding time window. Because the balancer does not keep any state, +it actually does not know the number of sessions. Instead it counts each request +without a session cookie or URL encoding as a new session. This method will neither +know, when a session is being invalidated, nor will it correct its load numbers +according to session timeouts or worker failover. This method should be used, +if sessions are your limiting resource, e.g. when you only have limited memory +and your sessions need a lot of memory. +</p> +<p> +If set to <b>T[raffic]</b> the balancer will use +the network traffic between JK and Tomcat to find the best worker. +Accesses will be distributed according to the lbfactor in a sliding time window. +This method should be used, if network to and from the backends is your +limiting resource. +</p> +<p> +If set to <b>B[usyness]</b> the balancer will +pick the worker with the lowest current load, based on how many requests the +worker is currently serving. This number is divided by the workers lbfactor, +and the lowest value (least busy) worker is picked. This method is especially +interesting, if your request take a long time to process, like for a download +application. +</p> +<p> +This feature has been added in <b>jk 1.2.9</b>. +The Session method has been added in <b>jk 1.2.20</b>. +</p> +</directive> + +<directive name="lock" default="Optimistic" required="false"> +Specifies what lock method the load balancer will use for synchronising +shared memory runtime data. +If lock is set to <b>O[ptimistic]</b> balancer will not use shared memory lock +to find the best worker. If set to <b>P[essimistic]</b> balancer will use +shared memory lock. The balancer will work more accurately in case of +Pessimistic locking, but can slow down the average response time. +<p> +This feature has been added in <b>jk 1.2.13</b>. +</p> +</directive> + +<directive name="retries" default="2" required="false"> +<warn>This directive also exists for normal workers. +For those it has a <a href="#Advanced Worker Directives">different meaning</a>.</warn> +If the load balancer can not get a valid member worker or in case of failover, +it will try again a number of times given by <b>retries</b>. +Before each retry, it will make a pause define by <b>retry_interval</b> directive. +<p> +Until version <b>1.2.16</b> the default value was 3. +</p> +</directive> + +</directives> + +</subsection> + +<subsection name="Status Worker Directives"> +<br /> +<p> +The status worker does not communicate with Tomcat. +Instead it is responsible for the load balancer management. +</p> +<directives> +<directive name="css" default="" required="false"> +Specifies the url for cascading stylesheet to use. +</directive> +<directive name="read_only" default="False" required="false"> +A status worker with read_only=True will not allow any operations, +that change the runtime state or configuration of the other workers. +These are edit/update/reset/recover. +<p> +This feature has been added in <b>jk 1.2.20</b>. +</p> +</directive> +<directive name="user" default="" required="false"> +It is a list of users +which gets compared to the user name authenticated by the web server. +If the name is not contained in this list, access is denied. Per +default the list is empty and then access is allowed to anybody. +<p> +This directive can be used multiple times. +</p> +<p> +This feature has been added in <b>jk 1.2.20</b>. +</p> +</directive> +<directive name="user_case_insensitive" default="False" required="false"> +By default, the user names are matched case sensitively. You can set +user_case_insensitive=True to make the comparison case insensitive. +This may be especially useful on the Windows platform. +<p> +This feature has been added in <b>jk 1.2.21</b>. +</p> +</directive> +<directive name="good" default="a.o,a.n,a.b,a.r" required="false"> +For every load balancer worker, the status worker shows a summary +of the state of its members. There are three such states, +"good", "bad" and "degraded". +<p> +These states are determined depending on the activation of the members +(active, disabled, stopped) and their runtime state +(ok, n/a, busy, recovering, probing, forced recovery, error). +By default, members are assumed to be "good", if their activation +is "active" and their runtime state is not "error". +</p> +<p> +You can change this mapping, by assigning a list of values to the +attribute "good". Each value gives a possible match for the members, +and one match suffices. Each value is either a single character, or two +characters combined with a dot ".". The single characters are the +first characters in the words "active", "disabled", "stopped", +"ok", "na", "busy", "recovering", "error". The additional states "probing" +and "forced recovery" are always rated equivalent to "recovering". +If a value consists only +of a single character, then all members with this activation or runtime +state will be assumed good. A combination of an activation and a runtime +state concatenated with a dot "." does only apply to a member, that has +exactly this activation and state. +</p> +<p> +Members of a load balancer will first be matched against the state "bad", +if they don't match, the state "good" will be tried, and if they +still don't match, their state will be "degraded". +</p> +<p> +This directive can be used multiple times. +</p> +<p> +This feature has been added in <b>jk 1.2.20</b>. +</p> +</directive> +<directive name="bad" default="s,e" required="false"> +See: "good". +<p> +By default, members are assumed to be "bad", if their activation +is "stopped" or their runtime state is "error". +</p> +<p> +This directive can be used multiple times. +</p> +<p> +This feature has been added in <b>jk 1.2.20</b>. +</p> +</directive> +<directive name="prefix" default="worker" required="false"> +The prefix, which will be used by the status worker +when producing properties output (mime=prop). +Each property key will be prefixed by this value. +<p> +This feature has been added in <b>jk 1.2.20</b>. +</p> +</directive> +<directive name="ns" default="jk:" required="false"> +This directive can be used to customise the XML output from the +status worker. If set to <b>-</b> no namespace will be used. +<p> +This feature has been added in <b>jk 1.2.20</b>. +</p> +</directive> +<directive name="xmlns" default="" required="false"> +This directive can be used to customise the XML output from the +status worker. If set to <b>-</b> no xmlns will be used. +<p> +Default value is set to xmlns:jk="http://tomcat.apache.org" +</p> +<p> +This feature has been added in <b>jk 1.2.20</b>. +</p> +</directive> +<directive name="doctype" default="" required="false"> +This directive can be used to customise the XML output from the +status worker. This value will be inserted to the output xml +after the xml header. +<p> +This feature has been added in <b>jk 1.2.20</b>. +</p> +</directive> + +</directives> +</subsection> + +<subsection name="Advanced Worker Directives"> +<br /> +<p> +This table lists more advanced configuration options. Most of them only apply to +some types of workers. We use the abbreviations <b>AJP</b> for ajp13/ajp14 workers +used directly via the workers.list, <b>LB</b> for load balancer workers, +and <b>SUB</b> for the workers used indirectly in a load balancer worker +as a sub worker or member. +</p> +<advanceddirectives> +<directive name="connect_timeout" workers="AJP,SUB" default="0" required="false"> +Connect timeout property told webserver to send a PING request on ajp13 connection after +connection is established. The parameter is the delay in milliseconds to wait for the PONG reply. +The default value zero disables the timeout (infinite timeout). +<p> +This features has been added in <b>jk 1.2.6</b> to avoid problem with hung Tomcat's and require ajp13 +ping/pong support which has been implemented on Tomcat <b>3.3.2+, 4.1.28+ and 5.0.13+</b>. +Disabled by default. +</p> +</directive> + +<directive name="prepost_timeout" workers="AJP,SUB" default="0" required="false"> +Prepost timeout property told webserver to send a PING request on ajp13 connection before +forwarding to it a request. The parameter is the delay in milliseconds to wait for the PONG reply. +The default value zero disables the timeout (infinite timeout). +<p> +This features has been added in <b>jk 1.2.6</b> to avoid problem with hung Tomcat's and require ajp13 +ping/pong support which has been implemented on <b>Tomcat 3.3.2+, 4.1.28+ and 5.0.13+</b>. +Disabled by default. +</p> +</directive> + +<directive name="reply_timeout" workers="AJP,SUB" default="0" required="false"> +The parameter is the number of milliseconds to wait for success during a read event. +So this is not a timeout for the complete answer time of a request, but only +for the maximum time between two packets received from Tomcat. Usually the longest +pause is between sending the request and getting the first packet of the response. +<p> +If the timeout passes without any data received from Tomcat, the webserver will +no longer wait for the rest of the response and send an error to the client (browser). +Usually this does not mean, that the request is also aborted on the Tomcat backend. +If the worker is a member of a load balancer, the load balancer might place the +worker into an error state and retry the request on another member. +See also <b>max_reply_timeouts</b>, <b>retries</b> and <b>recovery_options</b>. +</p> +<p> +By default (value zero) the webserver will wait forever which could be an issue for you. +If you set a reply_timeout, adjust it carefully if you have long running servlets. +</p> +<p> +The reply_timeout can be overwritten using the Apache httpd environment variable +JK_REPLY_TIMEOUT. +</p> +<p> +This features has been added in <b>jk 1.2.6</b> to avoid problem with hung Tomcat's and works on all +servlet engines supporting ajp13. The variable JK_REPLY_TIMEOUT has been added in version <b>1.2.27</b>. +</p> +</directive> + +<directive name="retries" workers="AJP,SUB" default="2" required="false"> +<warn>This directive also exists for load balancer workers. +For those it has a <a href="#Load Balancing Directives">different meaning</a>.</warn> +The maximum number of times that the worker will send a request to Tomcat +in case of a communication error. Each retry will be done over another +connection. The first time already gets counted, so retries=2 means +one retry after error. Before a retry, the worker waits for a configurable +sleeping time. +<p> +See also the attribute <b>recovery_options</b> for a more fine-grained control +of retries and <b>retry_interval</b> for the sleep time configuration. +</p> +<p> +Until version <b>1.2.16</b> the default value was 3. +</p> +</directive> + +<directive name="retry_interval" workers="AJP,SUB" default="100" required="false"> +The amount of time in milliseconds the worker sleeps before doing any retry. +<p> +This features has been added in <b>jk 1.2.27</b>. +</p> +</directive> + +<directive name="recovery_options" workers="AJP,SUB" default="0" required="false"> +Recovery options influence, how we should handle retries, +in case we detect a problem with Tomcat. +How often we will retry is controlled by the attribute <b>retries</b>. +<p> +This attribute is a bit mask. The following bits are allowed:<br/> +1: don't recover if Tomcat failed after getting the request<br/> +2: don't recover if Tomcat failed after sending the headers to client<br/> +4: close the connection to Tomcat, if we detect an error when writing back +the answer to the client (browser)<br/> +8: always recover requests for HTTP method HEAD (even if Bits 1 or 2 are set)<br/> +16: always recover requests for HTTP method GET (even if Bits 1 or 2 are set)<br/> +</p> +<p> +This features has been added in <b>jk 1.2.6</b>. +Option 4 has been added in version <b>1.2.16</b>, +options 8 and 16 in version <b>1.2.24</b>. +</p> +</directive> + +<directive name="fail_on_status" workers="AJP,SUB" default="0" required="false"> +Set this value to the HTTP status code that will cause a worker to fail +if returned from Servlet container. Use this directive to deal with +cases when the servlet container can temporary return non-200 responses +for a short amount of time, e.g during redeployment. +<p> +The error page, headers and status codes of the original response will not be send back +to the client. Instead the request will result in a 503 response. +If the worker is a member of a load balancer, the member will +be put into an error state. Request failover and worker recovery will be handled +with the usual load balancer procedures. +</p> +<p> +This feature has been added in <b>jk 1.2.20</b>. +</p> +<p> +Starting with <b>jk 1.2.22</b> it is possible to define multiple +status codes separated by space or comma characters. +For example: <code>worker.xxx.fail_on_status=500,503</code> +</p> +<p> +Starting with <b>jk 1.2.25</b> you can also tell the load +balancer to not put a member into an error state, if a +response returned with one of the status codes in +fail_on_status. This feature gets enabled, by putting a minus sign in +front of those status codes. +For example: <code>worker.xxx.fail_on_status=-404,-500,503</code> +</p> +</directive> + +<directive name="max_packet_size" workers="AJP,SUB" default="8192" required="false"> +This attribute sets the maximal AJP packet size in Bytes. +The maximum value is 65536. If you change it from the default, +you <b>must</b> also change the packetSize attribute of your AJP +connector on the Tomcat side! The attribute packetSize is only available +in Tomcat 5.5.20+ and 6.0.2+. +<p> +Normally it is not necessary to change the maximum packet size. Problems +with the default value have been reported when sending certificates or +certificate chains. +</p> +<p> +This feature has been added in <b>jk 1.2.19</b>. +</p> +</directive> + +<directive name="mount" workers="AJP,LB" default="" required="false"> +Space delimited list of uri maps the worker should handle. It is only used, +if the worker is included in worker.list. +<p> +This directive can be used multiple times for the same worker. +</p> +</directive> + +<directive name="secret" workers="AJP,LB,SUB" default="" required="false"> +You can set a secret keyword on the Tomcat AJP Connector. Then only requests +from workers with the same secret keyword will be accepted. +<p> +Use <b>request.secret="secret key word"</b> in your Tomcat AJP Connector configuration. +</p> +<p> +If you set a secret on a load balancer, all its members will inherit this secret. +</p> +<p> +This feature has been added in <b>jk 1.2.12</b>. +</p> +</directive> + +<directive name="max_reply_timeouts" workers="LB" default="0" required="false"> +If you use a <b>reply_timeout</b> for the members of a load balancer worker, +and you want to tolerate a few requests taking longer than reply_timeout, +you can set this attribute to some positive value. +<p> +Long running requests will still time out after reply_timeout milliseconds waiting for +data, but the corresponding member worker will only be put into an error state, +if more than <b>max_reply_timeouts</b> requests have timed out. +More precisely, the counter for those bad requests will be divided by two, +whenever the load balancer does its internal maintenance (by default every 60 +seconds). +</p> +<p> +This features has been added in <b>jk 1.2.24</b> to make <b>reply_timeout</b> less +sensitive for sporadic long running requests. +</p> +</directive> + +<directive name="recover_time" workers="LB" default="60" required="false"> +The recover time is the time in seconds the load balancer will not try +to use a worker, after it went into error state. Only after this time has passed, +a worker in error state will be marked as in recovering, so that it will be +tried for new requests. +<p> +This interval is not checked every time a request is being processed. +Instead it is being checked during global maintenance. The time between two +runs of global maintenance is controlled by worker.maintain. +</p> +<p> +Do not set recover_time to a very short time unless you understand the implications. +Every recovery attempt for a worker in error is done by a real request! +</p> +</directive> + +<directive name="error_escalation_time" workers="LB" default="recover_time / 2" required="false"> +Setting a member of a load balancer into an error state is quite serious. E.g. +it means that if you need stickyness, all access to the sessions of the +respective node is blocked. +<p> +Some types of error detection do not provide a precise information, whether +a node is completely broken or not. In those cases an LB will not immediately +put the node into the error state. Only when there have been no successful +responses for <b>error_escalation_time</b> seconds after such an error, +will the node be put into error state. +</p> +<p> +This features has been added in <b>jk 1.2.28</b>. +</p> +</directive> + +<directive name="activation" workers="SUB" default="Active" required="false"> +Using this directive, a balanced worker of a load balancer +can be configured as disabled or stopped. A disabled worker only gets +requests, which belong to sessions for that worker. A stopped +worker does not get any requests. Users of a stopped worker will +loose their sessions, unless session replication via clustering is used. +<p> +Use <b>d</b> or <b>D</b> to disable and <b>s</b> or <b>S</b> to stop. +If this directive is not present the deprecated directives +"disabled" or "stopped" are used. +</p> +<p> +This flag can be changed at runtime using status worker. +</p> +<p> +This feature has been added in <b>jk 1.2.19</b>. +</p> +</directive> + +<directive name="route" workers="SUB" default="worker name" required="false"> +Normally the name of a balanced worker in a load balancer is equal to the jvmRoute +of the corresponding Tomcat instance. If you want to include a worker corresponding +to a Tomcat instance into several load balancers with different balancing configuration +(e.g. disabled, stopped) you can use this attribute. +<p> +Define a separate worker per lb and per Tomcat instance with an arbitrary worker name and +set the route attribute of the worker equal to the jvmRoute of the target Tomcat instance. +</p> +<p> +If this attribute is left empty, the name of the worker will be used. +</p> +<p> +This attribute can be changed at runtime using status worker. +</p> +<p> +If the route name contains a period, the part before the first period will be +used as domain name, unless domain is set explicitly. +</p> +<p> +This feature has been added in <b>jk 1.2.16</b>.<br/> +The automatic domain rule has been added in <b>jk 1.2.20</b>.<br/> +The attribute has been renamed from jvm_route to route in <b>jk 1.2.20</b>. +</p> +</directive> + +<directive name="distance" workers="SUB" default="0" required="false"> +An integer number to express preferences between +the balanced workers of an lb worker. +A load balancer will never choose some balanced worker +in case there is another usable worker with lower distance. +<p> +Only in case all workers below a given distance are in error, disabled or stopped, +workers of a larger distance are eligible for balancing. +</p> +<p> +This feature has been added in <b>jk 1.2.16</b>. +</p> +</directive> + +<directive name="domain" workers="SUB" default="" required="false"> +Domain directive can be used only when the worker is a member of the load balancer. +Workers that share the same domain name are treated as single worker. If sticky_session +is used, then the domain name is used as session route. +<p> +This directive is used for large system with more then 6 Tomcats, to be able +to cluster the Tomcats in two groups and thus lowering the session replication +transfer between them. +</p> +<p> +This feature has been added in <b>jk 1.2.8</b>. +</p> +</directive> + +<directive name="redirect" workers="SUB" default="" required="false"> +Set to the name of the preferred failover worker. If worker matching +SESSION ID is in error state then the redirect worker will be used instead. +It will be used even if being disabled, thus offering hot standby. +<p> +If you explicitly set a route via the "route" attribute, you must set "redirect" +to this route of the preferred failover worker and not to its name. +</p> +<p> +This feature has been added in <b>jk 1.2.9</b>. +</p> +</directive> + +<directive name="session_cookie" workers="LB" default="JSESSIONID" required="false"> +The name of the cookie that contains the routing identifier needed for session stickyness. +The routing identifier is everything after a "." character in the value of the cookie. +<p> +This feature has been added in <b>jk 1.2.27</b>. +</p> +</directive> + +<directive name="session_path" workers="LB" default=";jsessionid" required="false"> +The name of the path parameter that contains the routing identifier needed for +session stickyness. The routing identifier is everything after a "." character in the value +of the path parameter. +<p> +This feature has been added in <b>jk 1.2.27</b>. +</p> +</directive> + +</advanceddirectives> +</subsection> + +<subsection name="Deprecated Worker Directives"> +<br/> +<p>The following directives have been deprecated in the past. We include their documentation +in case you need to use an older version of mod_jk. We urge you to update and not use +them any more. Please migrate your existing configurations. +</p> +<deprecations> +<directive name="cachesize" successor="connection_pool_size" default="see text" required="false"> +<warn>This directive has been deprecated since 1.2.16.</warn> +Cachesize defines the number of connections made to the AJP backend that +are maintained as a connection pool. +It will limit the number of those connection that each web server child +process can make. +<p> +Cachesize property is used only for multi threaded +web servers such as Apache 2.0 (worker), IIS and Netscape. The cachesize property +should reflect the number of threads per child process. JK will discover +the number of threads per child process on Apache 2 web server with worker-mpm and set +its default value to match the ThreadsPerChild Apache directive. For IIS the default +value is 10. For other web servers than Apache or IIS this value has to be set manually. +</p> +<warn>Do not use cachesize with values higher then 1 on <b>Apache 2.x prefork</b> or <b>Apache 1.3.x</b>!</warn> +</directive> + +<directive name="cache_timeout" successor="connection_pool_timeout" default="0" required="false"> +<warn>This directive has been deprecated since 1.2.16.</warn> +Cache timeout property should be used with <b>cachesize</b> to specify how to time JK should keep +an open socket in cache before closing it. This property should be used to reduce the number of threads +on the Tomcat web server. +<p> +Each child could open an ajp13 connection if it have to forward a request to Tomcat, creating +a new ajp13 thread on Tomcat side. +</p> +<p> +The problem is that after an ajp13 connection is created, the child won't drop it +until killed. And since the webserver will keep its childs/threads running +to handle high-load, even it the child/thread handle only static contents, you could +finish having many unused ajp13 threads on the Tomcat side. +</p> +</directive> + +<directive name="recycle_timeout" successor="connection_pool_timeout" default="0" required="false"> +<warn>This directive has been deprecated since 1.2.16.</warn> +The number of seconds that told webserver to cut an ajp13 connection after some time of +inactivity. When choosing an endpoint for a request and the assigned socket is open, it will be +closed if it was not used for the configured time. +It's a good way to ensure that there won't too old threads living on Tomcat side, +with the extra cost you need to reopen the socket next time a request be forwarded. +This property is very similar to <b>cache_timeout</b> but works also in non-cache mode. +If set to value zero (default) no recycle will took place. +</directive> + +<directive name="balanced_workers" successor="balance_workers" default="" required="true"> +<warn>This directive has been deprecated since 1.2.7.</warn> +A comma separated list of workers that the load balancer +need to manage. +</directive> + +<directive name="disabled" successor="activation" default="False" required="false"> +<warn>This directive has been deprecated since 1.2.19.</warn> +If set to <b>True</b> or <b>1</b> the worker will be disabled if member +of load balancer. This flag can be changed at runtime using status worker. +<p> +This feature has been added in <b>jk 1.2.9</b>. +</p> +</directive> + +<directive name="stopped" successor="activation" default="False" required="false"> +<warn>This directive has been deprecated since 1.2.19.</warn> +If set to <b>True</b> or <b>1</b> the worker will be stopped if member +of load balancer. The flag is needed for stop complete traffic of a sticky session +worker. It is only useful, when you have a cluster that replicated the sessions. +This flag can be changed at runtime using status worker. +<p> +This feature has been added in <b>jk 1.2.11</b>. +</p> +</directive> + +<directive name="jvm_route" successor="route" default="worker name" required="false"> +<warn>This directive has been deprecated since 1.2.20.</warn> +Normally the name of a balanced worker in a load balancer is equal to the jvmRoute +of the corresponding Tomcat instance. If you want to include a worker corresponding +to a Tomcat instance into several load balancers with different balancing configuration +(e.g. disabled, stopped) you can use this attribute. +<p> +Define a separate worker per lb and per Tomcat instance with an arbitrary worker name and +set the jvm_route attribute of the worker equal to the jvmRoute of the target Tomcat instance. +</p> +<p> +If this attribute is left empty, the name of the worker will be used. +</p> +<p> +This attribute can be changed at runtime using status worker. +</p> +<p> +This feature has been added in <b>jk 1.2.16</b>. +</p> +</directive> + +</deprecations> +</subsection> + +</section> + +</body> +</document> |