*jlinker-default-connection-pool*

This variable was added in a patch release in late July, 2013. That patch upgraded jlinker to version 7.1. See jlinker.htm for more information on the patch and version 7.1.

This variable specifies the default parameters for a jlinker connection pool.

The initial value is nil to specify no connection pool (for compatibility with earlier versions where connection pooling was not available).

A typical value is a list of the form

   (lisp-min lisp-max lisp-idle java-min java-max java-idle)

where

• lisp-min is the minimum number of connection pool ports from Lisp to Java
• lisp-max is the maximum number of connection pool ports from Lisp to Java
• lisp-idle is the maximum idle time allowed for a port from Lisp to Java
• java-min is the minimum number of connection pool ports from Java to Lisp
• java-max is the maximum number of connection pool ports from Java to Lisp
• java-idle is the maximum idle time allowed for a port from Java to Lisp

All values are positive integers, 0 or -1 (see below for the meanings of 0 and -1).

This list can be abbreviated by the following shorter forms:

;;  A single number n denotes the list 

   (h n 0 h n 0)

;; where h == (ceiling n 2)

;; A 2-element list (a b) denotes the list 

  (h a 0 k b 0)

;; where h == (ceiling a 2) and k = (ceiling b 2)

The effective connection pool parameters are determined by comparing this list with a corresponding list from the Java side. The comparison is made using the following rules:

• A -1 value in any position means to use the value from the other side.
• If both values are positive, use the minimum.
• If the effective value of lisp-min or java-min is zero, connection pooling is disabled.
• If both mins or maxes are -1 (meaning use the value from the other side), use the value 1.
• If both idle values are -1, use the value 0.
• If a max value is less than a min value, an error is signaled. (So if both maxes are -1 and both mins are greater than 1, an error will result since both maxes will be set to 1 which is less than the min values).
• An idle value of zero denotes an indefinite period.

Each port from Lisp to Java represents a socket connection in Lisp and a thread in Java.

Each port from Java to Lisp represents a socket connection In Java and a thread (Lisp process) in Lisp.

Ports up to the minimum number are created during jlinker initialization (but after jlinker-init returns). Ports above the minumum number are created on demand. The idle times apply to ports above the minimum number; if one such port is idle for the specified time, it is closed and the associated thread ended.

See jlinker.htm for more information on the jLinker facility.

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This page is new in the 9.0 release.
Created 2019.8.20.