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wrapper.jvm.port Property
wrapper.jvm.port Property
Configuration Property Overview
wrapper.jvm.port

The Wrapper uses a socket to communicate with its Java component running inside a JVM. This property allows the configuration of the port that the JVM will use to connect back to the Wrapper. Most applications need not specify this property as the default value of 0, which instructs the JVM to choose its own port, will be sufficient.

When a port of 0 is specified, the Wrapper will search for the first available port starting with port number 31000. If a valid port can not be found within the first 1000 attempts then the Wrapper will fail with an error. To my knowledge, this has never been seen. This means that auto allocated ports will fall in the range 31000-31999.

If a specific port should be used, then any port in the range 1-65535 may be specified. Note that on UNIX systems port numbers below 1024 will most likely require root access to be set. If the specified port is in use then the Wrapper will display a warning to the log and, as with the default case, will search for the first available port.

When the Wrapper launches a JVM instance, it will open a server socket listening on the port defined by the wrapper.port property. The JVM will then connect back to Wrapper, internally using the port specified by this property.

Example:
wrapper.jvm.port=1778
Controlling the port range.

In some cases, it is necessary to control the range of ports that the Wrapper will use when choosing a port. The defaults were chosen to make it very unlikely that they would conflict with any well known ports. If the default 31000-31999 range is causing problems, it can be changed using the wrapper.jvm.port.min and wrapper.jvm.port.max properties. If these are used, be sure to provide a large enough range to make it unlikely that all of the ports will be in use when the Wrapper attempts to start.

Example:
wrapper.jvm.port.min=31000
wrapper.jvm.port.max=31999

by Leif Mortenson

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