make-process-pool

Arguments: &key active-limit idle-limit idle-timeout name report-start report-end class process-class prime stack-allocation

Create and return a new process-pool instance. The keyword arguments specify initial values for the corresponding slots.

• active-limit: A positive integer specifying the maximum number of active processes allowed in the pool. Although permitted, it does not make sense for this value to be smaller than idle-limit, as then there would always be idle processes using resources but not running. Since this value is constrained by operating system resources, hardware configuration and application requirements, there is no reasonable built-in default. If not specified, the default value is taken from *process-pool-default-active-limit*.
• idle-limit: A positive integer specifying the maximum number of idle processes allowed in the pool. The default is the value of active-limit. Although permitted, it does not make sense for this value to be larger than active-limit, as then there would always be idle processes using resources but not running.
• class: A symbol naming a subclass of process-pool (the default).
• process-class: A symbol naming subclass of pool-process (the default).
• prime: An integer less than or equal to idle-limit or any other non-nil value that is not a number, or nil. If a positive integer, that number of pool processes will be created in idle state when the pool is created. If another non-nil value, idle-limit processes will be created. If nil (the default), no processes will be created.
• idle-timeout: The number of seconds an idle process is kept on the idle list. The default is nil meaning keep forever.
• name: The name of the process-pool. The name is also used for creating identifiers for certain other objects associated with the process-pool and thus helps identify which process-pool is meant in backtraces and error messages. The value must be a string. It value defaults to "ppN" where N is a unique integer. This value is not currently used for any other purpose.
• report-start: A function designator for the default report-start function or nil. When non-nil, the report-start function is called with a single argument, the work-item, when a process-pool-work-item is executed. The function specified here will be used if the work-item does not have its own non-nil report-start value. If you want to run a work-item with no report-start function, specifying nil as the report-start argument when creating the work item (directly with make-process-pool-work-item or as a side effect of calling process-pool-run) does not work as that means run this default report-start function. To have a report-start function that does nothing, define a function that does nothing and make it the report-start function for the work-item.
• report-end: A function designator for the default report-end function or nil. When non-nil, the report-end function is called with a three arguments when a process-pool-work-item is executed. The arguments are the work-item, the list of values returned by the work-item function, and the error condition if an error was signaled during the execution of the work-item. The report-end function specified here will be used if the work-item does not have its own report-end value. If you want to run a work-item with no report-end function, specifying nil as the report-end argument when creating the work item (directly with make-process-pool-work-item or as a side effect of calling process-pool-run) does not work as that means run this default report-end function. To have a report-end function that does nothing, define a function that does nothing and make it the report-end function for the work-item.
• stack-allocation: If specified, the value of this argument is passed to mp:make-process as the value of its stack-allocation argument when a new process is created for the process-pool. See the description of mp:make-process for complete details.

See Process pools in multiprocessing.htm for more information on process pools.

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This page is new in the 10.1 release.
Created 2019.8.20.