Appendix B. Worker Node Reference
B.1. Worker Configuration
Configuration values are sent to proxies under the following conditions:
- During server startup.
- When a proxy is detected through the advertise mechanism.
- During error recovery, when a proxy’s configuration is reset.
Table B.1. Proxy Configuration Values for Tomcat
Value | Default | Description |
---|---|---|
stickySession | true | Specifies whether subsequent requests for a given session should be routed to the same node, if possible. |
stickySessionRemove | false |
Specifies whether the Apache HTTP Server proxy should remove session stickiness if the balancer is unable to route a request to the node to which it is stuck. This property is ignored if |
stickySessionForce | true |
Specifies whether the Apache HTTP Server proxy should return an error if the balancer is unable to route a request to the node to which it is stuck. This property is ignored if |
workerTimeout | -1 |
Specifies the number of seconds to wait for a worker to become available to handle a request. When all the workers of a balancer are unusable, mod_cluster will retry after a while ( |
maxAttempts | 1 |
Specifies the number of times the Apache HTTP Server proxy will attempt to send a given request to a worker before aborting. The minimum value is |
flushPackets | false | Specifies whether packet flushing is enabled or disabled. |
flushWait | -1 |
Specifies the time to wait before flushing packets. A value of |
ping | 10 | Time to wait (in seconds) for a pong answer to a ping. |
smax |
Specifies the soft maximum idle connection count. The maximum value is determined by the Apache HTTP Server thread configuration ( | |
ttl | 60 |
Specifies the time (in seconds) idle connections persist, above the |
nodeTimeout | -1 |
Specifies the time (in seconds) mod_cluster waits for the back-end server response before returning an error. mod_cluster always uses a |
balancer | mycluster | Specifies the name of the load-balancer. |
loadBalancingGroup |
Specifies the load balancing among |
B.2. mod_cluster Proxy and Proxy Discovery Configuration Attributes
The following tables contain attributes and information about mod_cluster proxy, and proxy discovery configuration attributes.
Table B.2. mod_cluster Proxy Discovery Configuration Attributes
Attribute | Property | Default Value |
---|---|---|
proxy-list | proxyList | |
proxy-url | proxyURL | |
advertise | advertise | true |
advertise-security-key | advertiseSecurityKey | |
excluded-contexts | excludedContexts | |
auto-enable-contexts | autoEnableContexts | true |
stop-context-timeout | stopContextTimeout | 10 seconds (in seconds) |
socket-timeout | nodeTimeout | 20 seconds (in milliseconds) |
When nodeTimeout
is not defined, the ProxyTimeout
directive, Proxy
, is used. If ProxyTimeout
is not defined, the server timeout (Timeout
) is used (120 seconds by default in the JBCS httpd.conf). nodeTimeout
, ProxyTimeout
, and Timeout
are set at the socket level.
Table B.3. mod_cluster Proxy Configuration Attributes
Attribute | Property | Default Value |
---|---|---|
sticky-session | stickySession | true |
sticky-session-remove | stickySessionRemove | false |
sticky-session-force | stickySessionForce | true |
node-timeout | workerTimeout | -1 |
max-attempts | maxAttempts | 1 |
flush-packets | flushPackets | false |
flush-wait | flushWait | -1 |
ping | ping | 10 (seconds) |
smax | smax | -1 (uses the default value) |
ttl | ttl | -1 (uses the default value) |
domain | loadBalancingGroup | |
load-balancing-group | loadBalancingGroup |
B.3. Load Configuration
The following table contains additional configuration properties that are used when mod_cluster is configured with Tomcat.
Table B.4. Load Configuration for Tomcat
Attribute | Default Value | Description |
---|---|---|
loadMetricClass | org.jboss.modcluster.load.metric.impl.BusyConnectorsLoadMetric |
The class name of an object that is implementing |
loadMetricCapacity | 1 |
The capacity of the load metric defined via the |
loadHistory | 9 | The number of historic load values that must be considered in the load balance factor computation. |
loadDecayFactor | 2 | The factor by which the historic load values decrease in significance. |